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  • 1995-1999  (745)
  • 1997  (745)
  • Inorganic Chemistry  (608)
  • Magnetic resonance imaging  (137)
  • 101
    Electronic Resource
    Electronic Resource
    Osteoid osteoma of the petrous bone (1997)
    Springer
    Neuroradiology 39 (1997), S. 821-823 
    Details
    ISSN: 1432-1920
    Keywords: Key words Osteoid osteoma ; Temporal bone ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present a case of osteoid osteoma of the petrous bone presenting with progressive sensorineural hearing loss. CT showed a dense homogeneous mass at the promontory surrounded by a thin bony border. On MRI this lesion gave intermediate signal intensity on T1- and T2-weighted spin-echo images and enhanced intensely with gadolinium. Surgical removal and pathological study proved the diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050514
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  • 102
    Electronic Resource
    Electronic Resource
    “Eraseroma” as a cause of rhinolith: CT and MRI in a child (1997)
    Springer
    Neuroradiology 39 (1997), S. 824-826 
    Details
    ISSN: 1432-1920
    Keywords: Key words Rhinolith ; Nose ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a 5-year old girl with progressive difficulty in breathing through the nose whose clinical diagnosis was nasal tumour. CT showed a calcified nodular mass and MRI a nonspecific nodular lesion in the right nasal cavity. The radiological suspicion was a rhinolith. The operative specimen showed that an eraser from a pencil was the primary source. We underline the rarity of this entity and the important role of radiological studies in preoperative recognition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050515
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  • 103
    Electronic Resource
    Electronic Resource
    Volumetric quantification of brain development using MRI (1997)
    Springer
    Neuroradiology 39 (1997), S. 841-846 
    Details
    ISSN: 1432-1920
    Keywords: Key words Cerebrum ; volume ; Quantification ; Cerebrum ; development ; Myelination ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We devised a three-dimensional method for estimation of cerebral development and myelination which measures cerebral volume using MRI. Accuracy of the system was estimated using cadaver brains. The mean percentage error in the calculated volumes compared with the real volumes was 2.33 %, range 0.00–5.33 %. We applied the method to the volume of both cerebral hemispheres (CH), basal ganglia, thalamus and internal capsule (BT), and myelinated white matter (WM) in 44 neurologically normal individuals (4 months to 28 years of age), 13 patients with spastic motor disturbances (2–25 years of age), and 9 patients with athetotic motor disturbances (2–23 years of age). In the neurologically normal cases, the volumes of CH, BT and WM increased with age; the volume of MW more slowly than that of CH. In cases with spastic motor disturbances, the volumes of CH, BT and WM were between –1.4 and 3.5 SD, –1.0 and –3.5 SD, and 0.0 and –5.2 SD respectively, of those of neurologically-normal cases. On the other hand, 7 of the 9 cases with athetotic motor disturbances were within 2 SD of the volume of CH in neurologically normal cases. Our method for direct measurement of cerebral volume based on serial MRI should be useful for the accurate assessment of brain development and quantitative analysis of delayed myelination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050517
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  • 104
    Electronic Resource
    Electronic Resource
    MRI and clinical features in amyotrophic lateral sclerosis (1997)
    Springer
    Neuroradiology 39 (1997), S. 847-851 
    Details
    ISSN: 1432-1920
    Keywords: Key words Amyotrophic lateral sclerosis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI of the brain and spinal cord was performed in 21 patients with amyotrophic lateral sclerosis (ALS), 8 normal volunteers and 16 neurological disease controls. High signal was seen in the intracranial corticospinal tract in 16 of the 21 patients on T2-weighted and in 10 on proton density (PD)-weighted images. In one patient, the high signal on T2-weighted images became less marked with progression of the disease. Low signal intensity was seen in the motor cortex in 12 of the 21 patients. High signal in the anterolateral column of the spinal cord on T1 weighted images was seen in 14, and high signal in the lateral corticospinal tract on T2 weighted images was seen in 7 of the 21 patients. The relationship between the abnormal images and upper motor neurone signs remained unclear. High signal intensity was seen in the corticospinal tract in the brain on T2-weighted images in two normal volunteers and four disease controls, and on PD weighted images in three disease controls. Low signal intensity in the motor cortex on T2 weighted images was seen in three normal volunteers and four disease controls. However, high signal intensity was seen in the intracranial corticospinal tract on T1 weighted images in five patients with ALS who showed pronounced upper motor neurone signs including spastic paraparesis, but not in controls. Thus, abnormalities on MRI in the brain and spinal cord should be considered in the diagnosis of ALS, and high signal intensity of the intracranial corticospinal tract on T1-weighted images may reflect the severe pathological changes of the upper motor neurones in ALS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050518
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  • 105
    Electronic Resource
    Electronic Resource
    Cerebral abscess with multiple rims on MRI (1997)
    Springer
    Neuroradiology 39 (1997), S. 857-859 
    Details
    ISSN: 1432-1920
    Keywords: Key words Brain ; abscess ; Nocardia asteroides ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present a patient with multiple brain abscesses caused by Nocardia asteroides. On T2-weighted MRI, multiple concentric rims were seen in the abscess, which could be a finding specific for infection. The rims may be due to organization of the necrotic debris and phagocytoses by macrophages in the capsule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050520
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  • 106
    Electronic Resource
    Electronic Resource
    Primary intrasellar germinoma with synchronous pineal tumor (1997)
    Springer
    Neuroradiology 39 (1997), S. 860-862 
    Details
    ISSN: 1432-1920
    Keywords: Key words Germ-cell neoplasms ; Pineal body ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Germinomas arising within the sella turcica are extremely rare. The association of intrasellar and a pineal region tumours is even more unusual. We report a 30-year-old man with germinomas in the sellar and pineal region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050521
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  • 107
    Electronic Resource
    Electronic Resource
    Spinal MRI in vacuolar myelopathy, and correlation with histopathological findings (1997)
    Springer
    Neuroradiology 39 (1997), S. 865-869 
    Details
    ISSN: 1432-1920
    Keywords: Key words Vacuolar myelopathy ; Human immunodeficiency virus ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We correlated MRI features with histopathological findings in an HIV-positive patient with vacuolar myelopathy. On MRI symmetrical nonenhancing high-signal areas in the posterior columns on T2-weighted images result from extensive vacuolation visible on histological sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050523
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  • 108
    Electronic Resource
    Electronic Resource
    High-signal lesions in the midbrain on T1-weighted MRI in an HIV-infected patient (1997)
    Springer
    Neuroradiology 39 (1997), S. 136-138 
    Details
    ISSN: 1432-1920
    Keywords: Key words Acquired immunodeficiency syndrome ; Human immunodeficiency virus ; Brain ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In addition to opportunistic infections, neoplasms or cerebrovascular complications, metabolic encephalopathies are a classical cause of diffuse brain dysfunction in HIV infection and are frequent in the terminal stage. We report an HIV-infected patient with symmetrical, focally increased signal in the midbrain on proton density- and T1-weighted MRI without corresponding high signal on T2-weighted images or on CT. While the precise nature and cause of this uncommon finding is not fully understood, the available evidence suggests that these lesions might represent a novel metabolic encephalopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050381
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  • 109
    Electronic Resource
    Electronic Resource
    Die infektiöse Spondylitis Eine retrospektive Auswertung der MRT-Merkmale (1997)
    Springer
    Der Radiologe 37 (1997), S. 139-144 
    Details
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Spondylitis ; Spondylodiszitis ; Wirbelkörper ; Bandscheibe ; Kernspintomographie ; Key words Spondylitis ; Spondylodiscitis ; Spine ; Intervertebral disc ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Aim and methods: The aim of the present study was to evaluate the MRI criteria of infectious spondylitis (spondylodiscitis). The MR images of 23 patients suffering from spondylodiscitis (78 % unspecific, 22 % specific) were retrospectively analyzed. Results: The height of the intervertebral discs involved was normal in 40 %, reduced in 43 % and increased in 17 % of the cases. The most common findings can be summarized in an MR triad: 1) The vertebral bodies involved are hypointense in T1-weighted images (100 %) with a lack of delineation of the intervertebral discs (53 %). 2) The injection of Gd-DTPA yields an enhancement of the vertebral bodies involved and intervertebral discs (95 % and 74 % respectively). 3) The vertebral bodies and intervertebral discs are hyperintense in T2-weighted sequences (76 % and 90 % respectively). When present, a paravertebral or intraspinal extension of the infection was isointense compared with the adjacent involved vertebral body in the majority of the patients. A differentiation between unspecific and specific etiology based on the MR images was not possible. Conclusions: The vertebral bodies affected were usually hypointense in T1-W with enhancement after the administration of Gd-DTPA and hyperintense in T2-W. The discs involved were usually hyperintense in T2-W and demonstrated an inhomogeneous enhancement.
    Notes: Zusammenfassung Um die kernspintomographischen Merkmale der Spondylitis zu überprüfen, wurden die MRT-Bilder von 23 Patienten mit einer Spondylitis (78 % unspezifisch, 22 % spezifisch) retrospektiv analysiert; 40 % der befallenen Bandscheiben zeigten eine normale Höhe, 43 % waren verschmälert und 17 % zeigten eine Höhenzunahme. Die häufigsten Veränderungen lassen sich in einer MRT-Trias zusammenfassen: 1. In T1-gewichteten Sequenzen sind die befallenen Wirbelkörper hypointens (100 %) und die Bandscheiben nicht abgrenzbar (53 %). 2. Wirbelkörper und Bandscheiben nehmen Kontrastmittel auf (95 bzw. 74 %). 3. Wirbelkörper und Bandscheiben sind in T2-gewichteten Sequenzen hyperintens (76 bzw. 90 %). Dabei stellt sich ein paravertebraler Weichteilbefall in allen Sequenzen isointens zum befallenen Wirbelkörper dar. Eine Differenzierung zwischen unspezifischer und spezifischer Ätiologie war kernspintomographisch nicht möglich.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050186
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  • 110
    Electronic Resource
    Electronic Resource
    Takayasu's arteritis: evaluation with three-dimensional time-of-flight MR angiography (1997)
    Springer
    European radiology 7 (1997), S. 44-50 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Pulseless disease ; Aortitis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Three-dimensional time-of-flight MR angiography was performed in 16 patients with Takayasu's arteritis. Two regions were evaluated, the arch of aorta and its intrathoracic major branches, and the abdominal aorta with proximal portions of its major visceral and renal branches. Individual arteries and aortic segments, i. e. aortic arch and abdominal aorta, were evaluated for abnormalities such as stenosis, occlusion, dilatation and aneurysm formation. The results were compared with contrast angiography. Follow-up MR angiography was performed in three patients after 9–12 months. MR angiography demonstrated steno-occlusive lesions in all the patients and aneurysms in 2. In comparison with contrast angiography, good correlation was found in 129 of the 145 arteries and aortic segments. For the 12 false-positive results, incorrect slab placement and overestimation of stenosis were implicated. Interestingly, there were three false-negative results and one occlusion was underestimated as stenosis. A new lesion developed in 1 patient and one stenosis progressed in another patient upon follow-up. Three-dimensional time-of-flight MR angiography is a simple and fairly accurate method for documenting the lesions in Takayasu's arteritis and for its follow-up.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050107
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  • 111
    Electronic Resource
    Electronic Resource
    Effects of lipiodol retention on MRI signal intensity from hepatocellular carcinoma and surrounding liver treated by chemoembolization (1997)
    Springer
    European radiology 7 (1997), S. 10-16 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Liver ; neoplasm ; Magnetic resonance imaging ; Contrast media ; fatty acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Opinion is divided regarding the influence of iodized oil on MRI signal intensity of hepatic tumours treated with transcatheter arterial chemoembolization (TACE), in which lipiodol deposits. The aim of our study was to ascertain whether or not lipiodol directly influences the MRI signal intensity of hepatocellular carcinoma (HCC) treated by TACE and that of the surrounding liver. Thirteen patients with HCC were studied retrospectively. CT and MRI scans were performed both before and 3 months after TACE. The CT scan was performed to check whether embolized nodules contained lipiodol and how lipiodol was distributed within them. In addition, eight patients were examined prospectively within 7 days after TACE. In these patients a CT scan was performed to see how lipiodol was distributed in the neoplastic nodules and in normal hepatic parenchyma. In the first group of patients the contrast-to-noise (C/N) ratio on T1-weighted (T1W) images and the T2 relaxation time on T2-weighted (T2W) images were calculated for both neoplasm and surrounding liver. In the second group of patients we also measured the signal intensity of non-neoplastic liver that was either permeated or not permeated by lipiodol. The data were analysed with Wilcoxon's test. On T1W images we observed that the retention of lipiodol increased the C/N ratio in all the tumours studied within 1 week after TACE. In the patients studied 3 months after TACE the C/N ratio was not significantly increased. On T2W images lipiodol retention did not change tumour signal intensity. The iodized oil did not change the signal intensity of the liver surrounding the tumour, in comparison with the liver not permeated by lipiodol, on either T1W or T2W images. The results indicate that lipiodol does not modify the signal intensity in non-neoplastic hepatic parenchyma in which it is deposited; after 3 months it does not significantly affect the signal of the tumours that accumulated it. Lipiodol produces a high signal on T1W images over the first few days following TACE in those tumours in which it is deposited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050099
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  • 112
    Electronic Resource
    Electronic Resource
    The relationship between the magnetic resonance imaging appearance of the lumbar spine and low back pain, age and occupation in males (1997)
    Springer
    European spine journal 6 (1997), S. 106-114 
    Details
    ISSN: 1432-0932
    Keywords: Magnetic resonance imaging ; Lumbar spine ; Disc disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to undertake a critical review of the potential role of magnetic resonance imaging (MRI) in the evaluation of low back pain (LBP) and to determine if there were differences in the MRI appearances between various occupational groups. The study group, 149 working men (78 aged 20-30 years and 71 aged 31–58 years) from five different occupations (car production workers, ambulance men, office staff, hospital porters and brewery draymen), underwent MRI of the lumbar spine. Thirty-four percent of the subjects had never experienced LBP Twelve months later, the examination was repeated on 89 men. Age-related differences were seen in the MRI appearances of the lumbar spine. Disc degeneration was most common at L5/S 1 and was significantly more prevalent (P 〈 0.01) in the older age group (52%) than in the younger age group (27%). Although LBP was more prevalent in the older subjects there was no relationship between LBP and disc degeneration. No differences in the MRI appearance of the lumbar spine were observed between the five occupational groups. Overall, 45% had ‘abnormal’ lumbar spines (evidence of disc degeneration, disc bulging or protrusion, facet hypertrophy, or nerve root compression). There was not a clear relationship between the MRI appearance of the lumbar spine and LBP. Thirty-two percent of asymptomatic subjects had ‘abnormal’ lumbar spines and 47% of all the subjects who had experienced LBP had ‘normal’ lumbar spines. During the 12-month follow-up period, 13 subjects experienced LBP for the first time. However, there was no change in the MRI appearances of their lumbar spines that could account for the onset of LBP. Although MRI is an excellent technique for evaluating the lumbar spine, this study shows that it does not provide a suitable pre-employment screening technique capable of identifying those at risk of LBP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01358742
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  • 113
    Electronic Resource
    Electronic Resource
    Facial palsy in multiple sclerosis (1997)
    Springer
    Journal of neurology 244 (1997), S. 631-633 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Facial palsy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Facial palsy occurred in 21 (19.6%) of 107 Japanese patients with multiple sclerosis (MS) during a mean follow-up period of 4.3 years. We observed residual signs of facial palsy in five other patients in whom acute onset was confirmed from medical records. Facial palsy began on average 7.6 years after the onset of MS but in five patients (4.7%) was the first symptom of MS, preceding the next MS symptom by 0.5–3 years. Facial palsy was usually associated with other brainstem signs, while two patients showed only facial palsy 1 and 3 years after the onset of MS. Twenty-one (84.0%) of the 25 patients who underwent brain magnetic resonance imaging (MRI) showed brainstem lesions in the pontine tegmentum ipsilateral to the facial palsy. However, the two patients without other symptoms or signs had no apparent causal lesion on MRI, which suggests difficulty in differentiating idiopathic Bell’s palsy from MS- associated facial palsy by MRI, although it has an excellent capacity to detect causal lesions of facial palsy associated with MS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050158
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  • 114
    Electronic Resource
    Electronic Resource
    Intra-observer reproducibility in measuring new putative MR markers of demyelination and axonal loss in multiple sclerosis: a comparison with conventional T2-weighted images (1997)
    Springer
    Journal of neurology 244 (1997), S. 266-270 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Magnetisation tranfer imaging ; Spinal cord ; Measurement ; reproducibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract New magnetic resonance (MR) measures considered to be putative markers of demyelination and axonal loss were found to be more closely related to clinical disability than T2-weighted MR imaging (MRI) findings in patients with multiple sclerosis (MS). In this study, we evaluated the reproducibility of such measurements in order to assess their reliability for longitudinal studies in MS. The intra-observer coefficients of variation for repeated measurements did not significantly differ among the MR techniques studied [2.6% for T2-weighted MRI, 4.38% for unenhanced T1-weighted MRI, 3.65% for magnetisation transfer imaging (MTI) and 2.28% for spinal cord cross-sectional area at C5]. Our findings suggest that non-conventional MR techniques may be reliable outcome measures for clinical trials in MS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050083
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  • 115
    Electronic Resource
    Electronic Resource
    Randomized placebo-controlled trial of mitoxantrone in relapsing-remitting multiple sclerosis: 24-month clinical and MRI outcome (1997)
    Springer
    Journal of neurology 244 (1997), S. 153-159 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Mitoxantrone ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We designed a randomized, placebo-controlled, multicentre trial involving 51 relapsing-remitting multiple sclerosis patients to determine the clinical efficacy of mitoxantrone treatment over 2 years. Patients were allocated either to the mitoxantrone group (27 patients receiving IV infusion of mitoxantrone every month for 1 year at the dosage of 8 mg/m2) or to the placebo group (24 patients, receiving IV infusion of saline every month for 1 year) using a centralized randomization system. Disability at entry and at 12–24 months was evaluated by four blinded neurologists trained in the application of the Kurtzke Expanded Disability Scale (EDSS). In addition, the number and clinical characteristics of the exacerbations over the 24 months were recorded by the local investigators. MRI, at 0,12 and 24 months, was performed with a 0.2 T permanent unit. MRI data were analysed by two blinded neuroradiologists. All patients underwent a clinical evaluation. A statistically significant difference in the mean number of exacerbations was observed between the mitoxantrone group and placebo group both during the 1st and the 2nd year. Although there was no statistically significant benefit in terms of mean EDSS progression over 2 years, the proportion of patients with confirmed progression of the disease, as measured by a one point increase on the EDSS scale, was significantly reduced at the 2nd year evaluation in the mitoxantrone group. Forty-two (23 mitoxantrone, 19 placebo) patients underwent all MRI examinations during the 24-month period. We observed a trend towards a reduction in the number of new lesions on T2-weighted images in the mitoxantrone group. Our study suggests that mitoxantrone might be effective in reducing disease activity, both by decreasing the mean number of exacerbations and by slowing the clinical progression sustained by most patients after 1 year from the end of treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050066
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  • 116
    Electronic Resource
    Electronic Resource
    Quantitative magnetic resonance analysis in vascular dementia (1997)
    Springer
    Journal of neurology 244 (1997), S. 246-251 
    Details
    ISSN: 1432-1459
    Keywords: Key words Vascular dementia ; Magnetic resonance imaging ; Neuropsychological assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The potential role of magnetic resonance imaging (MRI) in differentiating between specific causes of cognitive decline in patients with vascular dementia (VD) has not yet been fully established. We therefore decided to assess the supratentorial cerebral contents in 24 patients with a diagnosis of probable VD and in 24 normal subjects, matched for age and education level, using MRI volumetric parameters obtained by means of a quantitative method. The volumes of subarachnoid and ventricular spaces, cerebral tissue, and hyperintense areas on T2-weighted images were calculated. In order to reduce interindividual variability caused by differences in intracranial size, each absolute measurement was normalized to the relative size of the intracranial volume. In addition, we calculated the ratio between the areas of the corpus callosum (CC) and supratentorial brain at the same level on the T1-weighted image midsagittal plane. The MRI data were correlated with the deterioration of cognitive functions. Patients with VD showed significantly lower cerebral tissue volume and CC area, and higher ventricular space volume than normal subjects. Furthermore, the total volume of the T2 signal alterations was higher in VD patients than in normal subjects. In VD patients, this volume was found to be proportional to the increase in the volume of the ventricular space. On the other hand, no correlation was found between the volume of the T2 signal alterations and the area of the CC. The degree of global cognitive dysfunction and the score of each neuropsychological test did not show any correlation with the MRI data. Our results suggest that ventricular enlargement in VD patients is correlated with the increase in volume of the T2 signal abnormalities, but that the degree of global cognitive dysfunction is not influenced by the volume of these T2 signal abnormalities. Furthermore, the CC atrophy does not influence the score of any neuropsychological test or the degree of global cognitive dysfunction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050079
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  • 117
    Electronic Resource
    Electronic Resource
    Strategies for optimizing MRI techniques aimed at monitoring disease activity in multiple sclerosis treatment trials (1997)
    Springer
    Journal of neurology 244 (1997), S. 76-84 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Trial design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Serial magnetic resonance imaging (MRI) detects substantial subclinical disease activity in multiple sclerosis (MS) and is presently included in most treatment trials as an objective outcome measure. Our current knowledge of the role of MRI in MS treatment trials is derived from very limited patient studies, and the aim of this paper is to identify strategies to optimize the use of MRI in monitoring disease activity in treatment trials. The number of active lesions revealed by MRI can be used as the primary outcome measure in exploratory treatment trials. With monthly scanning, the majority of active lesions will be seen by virtue of a limited number of new areas of gadolinium enhancement. The contrast between enhancing lesions and background could be increased by: (1) using higher doses of gadolinium, (2) suppressing the background signal with magnetization transfer, (3) delayed scanning, or (4) a combination of these. Following a systematic comparison of those approaches, the effect on the sensitivity in detecting active lesions should be analysed with reference to the power of treatment trials. We present preliminary results showing marked agreement between observers in reporting enhancing lesions; however, with new acquisition strategies, the observer variation should be re-established in a multicentre fashion. In definitive trials, the increase in total lesion load serves as a secondary outcome measure. Since the majority of lesions making up the total lesion load are inactive during the study, spatial resolution should be maximized in order to preclude any artificial changes in lesion load to be superimposed (noise) upon the relatively small actual change (information). Reduction in measurement error can be attempted by improved acquisition techniques with increased lesion to background contrast. More importantly, improvement in quantitation techniques is warranted. With a 6% coefficient of variation in measuring a baseline lesion load, we calculate the standard error of the mean yearly increase in T2 lesion load (typically 10% in untreated patients) in a treatment arm of 124 patients to be 7.5%. A comparison of several quantitation techniques should be performed in a multicentre longitudinal fashion in order to include variation caused by both scanner and segmentation technique, in addition to biological activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050053
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  • 118
    Electronic Resource
    Electronic Resource
    The transverse magnetisation decay characteristics of longstanding lesions and normal-appearing white matter in multiple sclerosis (1997)
    Springer
    Journal of neurology 244 (1997), S. 125-130 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Axonal loss ; Disability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The characteristics of transverse magnetisation decay of 120 longstanding lesions and 40 regions of normal-appearing white matter have been analysed in 40 patients with multiple sclerosis (MS) and 10 normal controls. Fifty lesions showed a biexponential decay in which two water compartments – one probably intracellular, the other extracellular – could be defined. There was a higher frequency of biexponential lesions in patients with a primary progressive course but no significant difference between benign and secondary progressive groups. Seventy lesions showed a monoexponential decay, of which 31 showed a T2 of greater than 200 ms, implying that these lesions were predominantly composed of extracellular rather than intracellular water. The results imply that an expanded extracellular space within chronic MS brain lesions is a common finding at all levels of disability and disease course. In so far as an expanded extracellular space implies axonal loss, the results suggest that the latter occurs commonly in longstanding MS lesions. The lack of correlation with disability suggests a limited role for the technique in therapeutic monitoring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050061
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  • 119
    Electronic Resource
    Electronic Resource
    Surgical treatment of syringomyelia associated with spinal dysraphism (1997)
    Springer
    Child's nervous system 13 (1997), S. 194-200 
    Details
    ISSN: 1433-0350
    Keywords: Key words Spinal dysraphism ; Syringomyelia ; Magnetic resonance imaging ; Syringo-subarachnoid shunt ; Chiari malformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Clinical and radiological features of syringomyelia in 15 patients with spinal dysraphism are reported. There were 8 patients with occult spinal dysraphism (lumbosacral lipoma) and 7 with spina bifida aperta (meningomyelocele). Syringomyelia with spinal dysraphism can be radiologically divided into two types according to the dysraphic state. The syrinx in the patients with occult spinal dysraphism occurred immediately rostral to the lipoma and was localized to the lower thoracic to lumbar levels, while in the meningomyelocele patients the syrinx extended from the cervical to the thoracic level. Large syrinx formation was recognized in 1 of the 7 occult spinal dysraphism cases and 3 of the 8 meningomyelocele cases. For syringomyelia with occult spinal dysraphism, 4 patients underwent syringo-subarachnoid shunting (S-S shunt, 2 cases) or syringostomy (2 cases) during an untethering operation. In the case of meningomyelocele, S-S shunts were placed in 2 patients. Collapse of the syrinx was achieved in all 6 patients who underwent S-S shunting or syringostomy. Decreased size of the syrinx was also noted in 3 occult spinal dysraphism patients who underwent untethering operations alone. In conclusion, a large syrinx in the case of spinal dysraphism should be surgically treated. S-S shunting is effective in both types of syringomyelia. Foramen magnum decompression may be an alternative method of surgical treatment for syringomyelia in patients with meningomyelocele.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003810050068
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  • 120
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    Intramedullary chondroid tumors of bone: correlation of abnormal peritumoral marrow and soft-tissue MRI signal with tumor type (1997)
    Springer
    Skeletal radiology 26 (1997), S. 100-106 
    Details
    ISSN: 1432-2161
    Keywords: Key words Enchondroma ; Chondrosarcoma ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To determine whether enchondromas and chondrosarcomas can be differentiated on the basis of peritumoral MR signal abnormality. Design. STIR and T2-weighted MRI images were retrospectively assessed for the presence and extent of abnormal peritumoral marrow and soft-tissue signal. The cause of the peritumoral signal abnormality was determined by histologic correlation with resection specimens. The presence or absence of bone destruction was noted. Patients. Twenty-three patients were studied: ten with enchondromas (three men, seven women; ages 33–73 years) and 13 with chondrosarcomas (seven men, six women; ages 25–88 years). Results. Abnormal peritumoral marrow signal was present on STIR images around none of 10 enchondromas and all of 13 chondrosarcomas (P〈0.0001). The marrow signal abnormality corresponded histologically to fine marrow fibrosis in all cases. Adjacent abnormal soft-tissue signal was present on STIR images around none of ten enchondromas and eight (62%) of 13 chondrosarcomas (P=0.0026). Abnormal soft-tissue signal was more common around high-grade than low-grade chondrosarcomas (100% vs 38%, P=0.028), and was more extensive (mean extent 28 mm vs 8 mm; P〉0.04). In the subset of tumors without bone destruction, peritumoral marrow signal abnormality was present around none of ten enchondromas and all of five chondrosarcomas (P=0.0003); abnormal soft-tissue signal was present around none of ten enchondromas and two of five chondrosarcomas (P〉0.05). Conclusion. Abnormal marrow or soft-tissue signal around a chondroid tumor is suggestive of chondrosarcoma, even in the absence of bone destruction. STIR images are necessary for adequate detection of peritumoral signal abnormalities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050201
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  • 121
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    MRI diagnosis of diabetic muscle infarction: report of two cases (1997)
    Springer
    Skeletal radiology 26 (1997), S. 122-127 
    Details
    ISSN: 1432-2161
    Keywords: Key words Diabetes mellitus ; Muscle infarction ; Magnetic resonance imaging ; Pyomyositis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Diabetic muscle infarction (DMI) is a rare complication of diabetes mellitus occurring in patients with poorly controlled insulin-dependent diabetes. In previous reports, the diagnosis of this condition was based on the pathologic studies, although MRI examinations were performed in a few patients as part of the diagnostic work-up. In this report, we describe two additional cases of DMI where the diagnosis was based on the MRI findings in conjunction with the clinical picture and laboratory studies. The patients usually present with thigh or calf pain and swelling, are afebrile, and have normal white blood cell count. MRI examination typically shows diffuse swelling and increased signal intensity on T2-weighted images in the affected muscles, with no focal fluid collections. In the proper clinical setting, these findings are diagnostic of DMI and patients should be spared unnecessary invasive diagnostic examinations such as lower extremity venograms and biopsies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050205
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  • 122
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    Electronic Resource
    MR diagnosis of traumatic tear of the spring ligament in a pole vaulter (1997)
    Springer
    Skeletal radiology 26 (1997), S. 310-312 
    Details
    ISSN: 1432-2161
    Keywords: Key words Spring ligament ; Plantar calcaneonavicular ligament ; Ligament tear ; Navicular subluxation ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The spring ligament is a significant contributor to the stability of the talar head and longitudinal arch of the foot, lending importance to accurate radiologic diagnosis of injury. Using MR, we diagnosed a spring ligament tear with associated navicular dorsal subluxation, confirmed intraoperatively. To our knowledge, there are no previous reports of MR diagnosis of tear of the spring ligament.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050242
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  • 123
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    Electronic Resource
    Enlarged peroneal process with peroneus longus tendon entrapment (1997)
    Springer
    Skeletal radiology 26 (1997), S. 313-315 
    Details
    ISSN: 1432-2161
    Keywords: Key words Peroneal process ; Calcaneus ; Peroneus longus tendon ; Plain radiographs ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A 50-year-old man was treated conservatively for chronic bilateral ankle pain for several years. Plain radiographs obtained following exacerbation of symptoms showed bilateral enlarged peroneal processes. CT and MRI demonstrated bony detail of the unusual processes and also showed isolation of the peroneus longus tendons and associated tendinitis and partial tears.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050243
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  • 124
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    Electronic Resource
    Mycetoma of the calf (1997)
    Springer
    Skeletal radiology 26 (1997), S. 319-322 
    Details
    ISSN: 1432-2161
    Keywords: Key words Mycetoma ; Magnetic resonance imaging ; Calf ; Granulomatous infection ; Actinomycetes ; Sulfur granules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Actinomycetous infections typically involve either the head and neck or the extremities following a traumatic implantation. Classic clinical associations are draining sinus tracts. This case report describes the pathologic and MR findings of a relatively acute mycetomatous process involving the soft tissues. Pathologic findings in this case included an occasional granule composed of gram positive, thin branching elements. These and other findings were consistent with actinomycetes bacterium infection. The discussion centers around the use of MR, both with and without gadolinium, in evaluating this type of granulomatous infection. Infiltration of the adjacent subcutaneous tissues was easier to appreciate on both the T1-weighted images without gadolinium and the T1-weighted images with gadolinium when compared to the T2-weighted images. Signal characteristics as described in this case report may suggest a granulomatous process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050245
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  • 125
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    Electronic Resource
    A radiologist’s guide to the imaging in the diagnosis and treatment of developmental dysplasia of the hip (1997)
    Springer
    Skeletal radiology 26 (1997), S. 386-397 
    Details
    ISSN: 1432-2161
    Keywords: Key words Hip dislocation ; congenital ; Diagnostic imaging ; Tomography ; X-ray computed ; Magnetic resonance imaging ; Radiography ; Arthrography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Developmental dysplasia of the hip (DDH) has a broad spectrum of presentation with the minor findings resolving spontaneously and the most severe ones resulting in disability, if not diagnosed early in life. Diagnosis in the first few months of life allows conservative treatment with complete resolution in most cases. Suspicion of DDH is based on ethnic, family, and pregnancy history, and on physical examination of the newborn. Imaging assists in the diagnosis and follows the treatment. Different modalities have their own advantages and disadvantages. This article deals with the description of the disease, risk factors, statistics, the physical examination as applied to real-time sonography, and imaging (plain radiography, arthrography, computed tomography, and magnetic resonance imaging).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050253
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  • 126
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    Electronic Resource
    Role of MRI in the diagnosis of insufficiency fractures of the sacrum and acetabular roof (1997)
    Springer
    Skeletal radiology 26 (1997), S. 517-524 
    Details
    ISSN: 1432-2161
    Keywords: Key words Insufficiency fracture ; Sacrum ; Osteoporosis ; Magnetic resonance imaging ; Computed tomography ; Radionuclide study ; Acetabulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. To review the risk factors and the radiological appearance of insufficiency fractures of the sacrum and acetabular roof. Design and patients. Twenty patients with sacral and acetabular roof insufficiency fractures were reviewed retrospectively. There were 16 women (80%) and 4 males (age range 48–86 years, excluding an 8-year-old boy). Thirteen patients had a known tumour, and nine had received pelvic irradiation. All patients, except one who was asymptomatic, presented with low back or hip pain. In patients with a known tumor, metastases were suspected. Plain radiography (20), bone scintigrams (16), MR examinations (20), and bone densitometry (14) were performed. Nine patients also each had a CT scan. Results and conclusions. In three cases the CT scan performed 10–25 days after onset of symptoms was interpreted as normal. MR examination performed a few days after the CT scan showed in each of these three patients a fracture line with a band of edema. Scintigraphy was very sensitive, but the H-shaped pattern of sacral uptake, specific for an insufficiency fracture, was detected in only three of 16 cases. The earliest MR sign was medullary edema, seen as early as 18 days after the onset of symptoms. On spin echo (SE) T1-weighted images (T1WI), the hypointense signal of edema could mask a fracture line. On SE T2WI the fracture line could be detected within the hyperintense edema (10 of 17 patients with examinations including SE T2WI). However, in four patients a fracture of the sacrum was not seen on T2WI, these having been obtained in the axial plane. For this reason, intravenous gadolinium was injected, revealing a fracture line in 12 of 14 examinations, or fat suppression sequences were performed, revealing a fracture line in five of five cases. The total number of fractures detected was 17 [15 fractures of the sacrum (bilateral in 10 cases) and two of the acetabular roof]. At a later stage, the edema resolved and the fracture was clearly seen. The two cases of fracture of the acetabular roof were easily recognized at MRI, particularly in the sagittal plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002560050278
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  • 127
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    Electronic Resource
    Cerebral cavernous hemangiomas in childhood Clinical presentation and therapeutic considerations (1997)
    Springer
    Child's nervous system 13 (1997), S. 522-525 
    Details
    ISSN: 1433-0350
    Keywords: Key words Hemangioma ; Cavernoma ; Hamartoma ; Sequelae ; Epilepsy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cerebral cavernous hemangiomas (CCH) are relatively rare vascular hamartomas. Since the introduction of MRI there has been an increase in the number of case reports of CCH in the medical literature. CCH are often asymptomatic; they may, however, cause epilepsy or neurological deficits due to their space-occupying effects or hemorrhagic sequelae. The tendency of CCH to bleed has been well recognized, though gross hemorrhage is infrequent owing to the relatively low blood pressure and small blood flow in CCH. MRI findings of a CCH are characteristic and can differentiate the lesions from other vascular abnormalities. To date, there has been no consensus on indications for surgical intervention. Three cases are presented, which together demonstrate by their different presentation, clinical course and MRI findings that each patient with a CCH requires an individually tailored management. Presentation, clinical course and accessibility for operation are the factors that determine whether a surgical or a conservative approach should be adopted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003810050130
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  • 128
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    Electronic Resource
    Acute cerebellar ataxia in children (1997)
    Springer
    Child's nervous system 13 (1997), S. 542-545 
    Details
    ISSN: 1433-0350
    Keywords: Key words Acute cerebellar ataxia ; Demyelinating diseases ; Pontine encephalitis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acute cerebellar ataxia is a benign syndrome usually occurring after an acute febrile disease. In a few cases neuroradiological investigations reveal cerebellar alterations. Clinical and neuroradiological involvement of the brain stem has rarely been reported in the literature. We present five cases of acute cerebellar ataxia. In two cases the cerebellar symptomatology was associated with neurological signs of brain stem involvement. CT scans did not show any pathologic findings in three patients. MRI disclosed cerebellar or brain stem alterations in all the patients. Clinical and neuroradiological findings allow differentiation of this pathologic entity from other demyelinating or dysmyelinating diseases. The value of MRI in detection and localization of the lesions and in following their evolution is emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003810050134
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  • 129
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    Electronic Resource
    Importance of patient evaluation for long-term survival in medulloblastoma recurrence (1997)
    Springer
    Child's nervous system 13 (1997), S. 30-34 
    Details
    ISSN: 1433-0350
    Keywords: Key words Gamma knife ; GH therapy ; Medulloblastoma recurrence ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recurrence is a major cause of death in patients with medulloblastoma. Although the exact protocol for regular radiographic evaluation is sometimes a matter of debate, continuous follow up is necessary. We report a case of long-term survival after surgical removal of a subfrontal recurrent medulloblastoma, which occurred more than 3 years after total gross excision of the primary lesion and radiation therapy. The asymptomatic recurrence, which was detected by routine follow-up neuroimaging tests, was excised. The patient subsequently received gamma knife irradiation of the tumor bed followed by a course of ``8 in 1'' chemotherapy. ``Early delayed radionecrosis'' occurred 13 months after gamma knife treatment, which resolved spontaneously. Particularities of the case are discussed with reference to the location of the recurrent tumor, the possible patho-genetic causes and the side effects of treatment. We believe that this case and others reported in the literature underline the importance of continuous MRI surveillance of patients operated on for medulloblastoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003810050035
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  • 130
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    Electronic Resource
    Decline in isokinetic force with age: muscle cross-sectional area and specific force (1997)
    Springer
    Pflügers Archiv 434 (1997), S. 246-253 
    Details
    ISSN: 1432-2013
    Keywords: Key words MVC maximum voluntary contraction ; Myosin heavy chains ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Humans produce less muscle force (F) as they age. However, the relationship between decreased force and muscle cross-sectional area (CSA) in older humans is not well documented. We examined changes in F and CSA to determine the relative contributions of muscle atrophy and specific force (F/CSA) to declining force production in aging humans. The proportions of myosin heavy chain (MHC) isoforms were characterized to assess whether this was related to changes in specific force with age. We measured the peak force of isokinetic knee extension in 57 males and females aged 23–80 years, and used magnetic resonance imaging to determine the contractile area of the quadriceps muscle. Analysis of MHC isoforms taken from biopsies of the vastus lateralis muscle showed no relation to specific force. F, CSA, and F/CSA decreased with age. Smaller CSA accounted for only about half of the 39% drop in force that occurred between ages 65–80 years. Specific force dropped about 1.5% per year in this age range, for a total decrease of 21%. Thus, quantitative changes in muscle (atrophy) are not sufficient to explain the strength loss associated with aging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050392
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  • 131
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    Electronic Resource
    Localization of ectopic parathyroid glands using technetium-99m sestamibi imaging: Comparison with magnetic resonance and computed tomographic imaging (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 197-201 
    Details
    ISSN: 1619-7089
    Keywords: Technetium-99m sestamibi ; Computed tomography ; Magnetic resonance imaging ; Hyperparathyroidism ; Ectopic parathyroid imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the study was to compare the accuracy of technetium-99m sestamibi imaging for localization of ectopic parathyroid glands in patients with hyperparathyroidism with that of magnetic resonance (MR) and computed tomographic (CT) imaging. Eleven patients with primary (n=3) or secondary (n=8) hyperparathyroidism were studied with99mTc sestamibi parathyroid imaging CT and MR imaging. Images of the neck were acquired at 10 min and 2–3 after tracer injection. The three patients with primary hyperparathyroidism and five patients with secondary hyperparathyroidism underwent parathyroidectomy. The ectopic glands were confirmed by histopathological examination of the resected specimens. In respect of 20 parathyroid glands in the eight patients explored surgically, the sensitivity and specificity of sestamibi imaging were 70% (14/20) and 88%, respectively, those of CT, 40% (8/20) and 88%, and those of MR imaging, 60% (12/20) and 88%. Of these patients, three had parathyroid adenomas while five had hyperplasia (17 glands). Sestamibi imaging localized eight ectopic parathyroid glands, which were surgically confirmed (six were located in the thymus and two in the mediastinum). In one patient explored surgically, the ectopic gland was located outside the field of the MR coil. Although the remaining three cases of secondary hyperparathyroidism were not confirmed surgically, these patients demonstrated sestamibi uptake in five parathyroid glands, including three ectopic glands. MR images demonstrated abnormal parathyroid glands in the same regions as sestamibi imaging. Our data indicate that99mTc-sestamibi imaging should be used initially to localize the ectopic parathyroid glands in patients with hyperparathyroidism for anatomical guidance prior to MR or CT imaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02439553
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  • 132
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    Electronic Resource
    Exercise performance and magnetic resonance imaging-determined thigh muscle volume in children (1997)
    Springer
    European journal of applied physiology 76 (1997), S. 92-97 
    Details
    ISSN: 1439-6327
    Keywords: Key words Peak V ; O2 ; Anaerobic performance ; Muscle volume ; Magnetic resonance imaging ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study examined the relationships between thigh muscle volume (TMV) and aerobic and anaerobic performance in children. A total of 32 children, 16 boys and 16 girls, aged 9.9 (0.3) years completed a treadmill running test to exhaustion for the determination of peak oxygen uptake (peak V˙O2) and a Wingate Anaerobic Test (WAnT) for the determination of peak power (PP) and mean power (MP). The volume of the right thigh muscle was determined using magnetic resonance imaging. TMV was not significantly different in boys and girls [2.39 (0.29) l vs 2.18 (0.38) l, P 〉 0.05]. Peak V˙O2 and MP were significantly higher in boys than girls (P 〈 0.01) whether expressed in absolute, mass-related or allometrically scaled terms. Absolute PP was not significantly different in boys and girls but mass-related and allometrically scaled values were higher in boys (P 〈 0.01). TMV was correlated with absolute peak V˙O2, PP and MP in both sexes (r = 0.52–0.89, P 〈 0.01). In boys, mass-related PP was correlated with TMV (r =0.53, P 〈 0.01), and in girls mass-related peak V˙O2 was correlated with TMV (r = −0.61, P 〈 0.01). However, in neither sex were allometrically scaled peak V˙O2, PP or MP correlated with TMV (P 〉 0.05). There were no significant differences between boys and girls in terms of peak V˙O2, PP or MP when expressed in a ratio to TMV or allometrically scaled TMV. In conclusion, this study has demonstrated that, when body size is appropriately accounted for using allometric scaling, TMV is unrelated to indices of aerobic and anaerobic power in 10-year-old children. Furthermore, there appear to be no qualitative differences in the muscle function of boys and girls in respect of aerobic and anaerobic function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050218
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  • 133
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    Anatomy of the normal acromion investigated using MRI (1997)
    Springer
    Langenbeck's archives of surgery 382 (1997), S. 141-144 
    Details
    ISSN: 1435-2451
    Keywords: Schlüsselwörter Akromion ; Anatomie ; MRI ; Subakromialraum ; Key words Acromion ; Anatomy ; Magnetic resonance imaging ; Subacromial space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract The shape of the acromion is strongly associated with impingement syndrome and with rotator cuff tears. It is notoriously difficult to image the acromion with conventional radiography. We have developed MRI techniques to depict the acromion in its longitudinal axis. Furthermore, we have measured the subacromial space in both external and internal rotation. In previous studies, three types of acromial shape have been described with the type III or hooked acromion being present in 66% of cases with rotator cuff tears. We studied 31 normal shoulders in 29 people using MRI. Within this population aged 24–36 years, mean age 31 years, no type III acromions were found. Twenty-one were type I (67.7%) and 10 were type II (32.3%). In addition, we found no difference in subacromial height in external or internal rotation. Low rates of intra- and interobserver error were found. These results imply that the hooked acromion is not present in the normal population and is, therefore, likely to be an acquired abnormality.
    Notes: Zusammenfassung Die Form des Akromions ist entscheidend mit dem Impingementsyndrom und Rotatorenmanschettenrissen assoziiert. Es ist nur allzu bekannt, daß sich das Akromion mit herkömmlicher Radiographie nur schwierig darstellen läßt. Wir haben MRI-Techniken entwickelt, die es erlauben, das Akromion in seiner longitudinalen Achse darzustellen. Des weiteren haben wir den Subakromialraum sowohl in Außen- als auch in Innenrotation gemessen. In früheren Studien wurden 3 Typen der akromialen Form beschrieben, wobei der Typ 3 bzw. das Hooked-Akromion in 66% der Fälle von Rotatorenmanschettenrissen vorkommt. Wir untersuchten 31 normale Schultern bei 29 Personen mit MRI. In dieser Population mit einem Alter von 24–36 Jahren, Mittelwert 31 Jahre, wurde kein Typ-III-Akromion gefunden. 21 (67,7%) Schultern waren dem Typ I und 10 (32,3%) dem Typ II zuzuordnen. Zudem fanden wir keine Unterschiede der subakromialen Höhe in Außen- und Innenrotation. Mit Kontrollstudien wurden niedrige Intra- und Inter-Observer-Fehler nachgewiesen. Diese Ergebnisse zeigen daß das Hooked-Akromion in der Normalbevölkerung nicht auftritt und es sich hierbei demzufolge um eine erworbene Abnormalität handelt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008032
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    Staging of laryngeal cancer: Endoscopy, computed tomography and magnetic resonance versus histopathology (1997)
    Springer
    European archives of oto-rhino-laryngology and head & neck 254 (1997), S. S117 
    Details
    ISSN: 1434-4726
    Keywords: Laryngeal neoplasms ; Tumor staging ; Endoscopy ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An accurate pretherapeutic staging of laryngeal cancer is required for optimal treatment planning and for evaluation and comparison of the results of different treatment modalities. In this study, 45 consecutive patients with neoplasms of the larynx, treated surgically, were included in a prospective pretherapeutic staging protocol that included indirect laryngoscopy, direct microlaryngoscopy, contrast-enhanced computed tomography (CT) and Gd-DTPA-enhanced magnetic resonance imaging (MRI). The surgical specimens were cut in whole-organ slices parallel to the plane of the axial CT and MR images. The histologic findings were then compared with clinical findings, CT and MRI. These findings showed that clinical evaluation failed to identify tumor invasion of the laryngeal cartilages and extralaryngeal soft tissues, resulting in a low staging accuracy (55%). Many pT4 tumors were clinically understaged. The combination of clinical/endoscopic evaluation and either CT or MRI resulted in a significantly improved staging accuracy (80% vs 87%, respectively). MRI was significantly more sensitive but less specific than CT in detecting neoplastic cartilage invasion. MRI tended to overestimate neoplastic cartilage invasion to possibly result in overtreatment, while CT was found to underestimate neoplastic cartilage invasion and could lead to inadequate therapeutic decisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02439740
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  • 135
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    Patient selection and surgical results in obstructive sleep apnea (1997)
    Springer
    European archives of oto-rhino-laryngology and head & neck 254 (1997), S. S157 
    Details
    ISSN: 1434-4726
    Keywords: Obstructive sleep apnea ; Uvulopalatopharyngoplasty ; Upper airway ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In recent years, therapeutic methods have been effective in the management of snoring and sleep apnea. Successful results have been possible through conservative and surgical approaches when the nature and site of obstruction is ascertained by careful investigation. Sagittal magnetic resonance imaging (MRI) of the upper respiratory tract has been the most valuable diagnostic tool in patients with obstructive sleep apnea. This has made it possible to measure the dimensions and distance of the hard and soft palate and tongue base to the posterior pharyngeal wall. Surgery is only indicated when a site of obstruction can be completely determined. In this study, surgical approaches and results obtained in 50 patients after surgery for sleep apnea are presented. Uvulopalatopharyngoplasty (UPPP) had a higher success rate in patients with obstruction at the level of the soft palate, but this rate decreased when it was associated with hypopharyngeal obstruction or when there was hypopharyngeal obstruction alone. UPPP was found to be beneficial in patients with central apnea. Nasal pathologies also played an important role in sleep apnea. Better results were obtained when UPPP was performed in patients who were young, not obese and an apnea-hypopnea index was below 40. Some unusual pathologies included lingual tonsil hypertrophy in the adult, sublingual dermoid cysts and angioma of soft palate and were found to be the cause of OSA. After surgical excision of these pathologies, apneic periods disappeared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02439750
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  • 136
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    Hydrogen Bonding and Conformational Analysis of Chelate-Stabilized Alkoxopalladium(II) Complexes Derived from Amino Alcohol Ligands (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 35-44 
    Details
    ISSN: 0009-2940
    Keywords: Alkoxopalladium(II) ; Conformational analysis ; Hydrogen bonding ; Two-dimensional and cage structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of palladium acetate with two equivalents of di- and triethanolamines RN(CH2CH2OH)2 in the presence of a base affords the new chelate-stabilized alkoxo Pd(II) complexes [Pd(OCH2CH2N(R)CH2CH2OH)2] [R = Me (1), Et (2), n-Bu (3), benzyl (4) or CH2CH2OH (5)]. These N,O-ligated complexes are isolated in high yield as yellow, crystalline solids and are thermally stable despite the presence of several β-hydrogen atoms in the ligand system. Both complexes possess a square-planar palladium coordination geometry with the two oxygen atoms positioned mutually trans. The most notable difference in the molecular structures is that 1 forms a two dimensional network of intermolecular O-H≡O hydrogen bonds, whereas 5 forms intramolecular O-H⃛O hydrogen bonds, which cage the palladium center. In solution 1-4 exist as a diastereoisomeric mixture (a racemic enantiomeric pair SNSN, RNRN and a mesomeric form RNSN) in a 1:1 molar ratio, and this ratio is independent of temperature in nonalcoholic solvents, When complexes 1-4 are dissolved in protic solvents (e.g. MeOH) the diastereomeric excess is temperature-dependent due to an exchange process between the meso diastereoisomer and the (racemic) enantiomeric pair. Thermodynamic parameters for this process in a mixture of MeOH-toluene have been determined with NMR and show this process to be influenced by the steric nature of the alkyl substituent (R) on nitrogen. A conformational analysis based on 1H-NMR coupling constants within the N,O-chelate ring of complexes 1-4 provides details on the solution structure of the ring in both diastereoisomers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300106
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    Synthesis of Functionalized Carbamates through a Palladium-Catalyzed Reductive Carbonylation of Substituted Nitrobenzenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 13-22 
    Details
    ISSN: 0009-2940
    Keywords: Carbamates ; Catalysis ; Substituted nitrobenzenes ; Palladium ; Reductive carbonylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The palladium-catalyzed reductive carbonylation of ortho and para-substituted nitrobenzenes has proven to be an attractive route for the synthesis of functionalized carbamates. For the Pd(1, 10-phenanthroline)2(triflate)2 catalyst system, the scope of the reaction has been studied. Substrates with electron-donating substituents at the para position were found to decrease the catalytic activity, most probably as a result of their relatively low oxidizing capacity. the selectivity towards the desired carbamate, however, was increased for these substrates. Under the influence of electron-withdrawing substituents the azoxybenzene and azobenzene derivatives became important side products. Introduction of large steric hindrance at the ortho position of the nitro substrates gave rise to an interesting side reaction, viz. methoxylation of the aromatic ring. The methoxylation reaction appeared to occur on an intermediate species in the catalytic cycle. Several functionalities have shown to be resistant to the reaction conditions required for the conversion ot the nitro group. Especially with 4-nitrobenzoic acid, an extremely high activity and selectivity was found, thus yielding a very convenient synthesis for N-protected amines containing carboxylic acid function.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300104
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  • 138
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    Dimeric Silver(I) Complexes of Some Isothiazole-Based LigandsDedicated to Prof. Dr. Rolf Gleiter on the occasion of this 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 95-100 
    Details
    ISSN: 0009-2940
    Keywords: Isothiazole complexes ; Dinuclear silver(I) complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of isothiazole-based potential ligands bearing substituents with additional donor sites in the 5-position of the heterocycle was synthesized [3-Me-5-R-C3HNS; R = CH=N(CH2)2py (1), CH=NCH2py (2), CH2N(CH2CH2NEt2)2 (4), (CH2)2SMe (5)]. Upon reaction with AgO3SCF3 they formed complexes [(1)AgOSO2CF3]2 (6), [(2)AgOSO2CF3]2 (7), [(4)Ag]2+2(O3SCF-3)2 (8) and [(5)AgOSO2CF3]2 (9), respectively. 6, 8 and 9 were shown by X-ray structural analyses to consist of dimeric units L2Ag2+2, either discrete (8), coordinated by terminal CF3SO-3 units (6). In 8 and 9 the isothiazole moiety is bonded to the metal center via the ring-N. The coordination potential of the isothiazole heterocycle is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300115
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  • 139
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    Synthesis and Structure of Binuclear Single-Bridged Bis[(phosphane)gold(I)]halogenonium Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 115-118 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Bromonium complex ; Halogenonium complex ; Halogen, two-coordinate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of (R3P)AuX (X = Cl, Br, I) with [(R3P)Au]+ BF-4 obtained from (R3P)AuCl and AgBF4 in tetrahydrofuran, lead to cationic binuclear gold(I) complexes of the general formula ([(R3P)Au]2X}+ BF-4. A number of chloro- (R = Ph, o-Tol, Mes, Bzl, Et), bromo- (R = Ph, o-Tol, Mes) and iodo-bridged (R = Ph, Mes) complexes of this type have been isolated and identified on the basis of their analytical and spectroscopic data. The crystal structure of bis[(triphenylphosphane)gold(I)]bromonium tetrafluoroborate was determined by single-crystal X-ray diffraction. The cations contain two-coordinate bromine atoms with an Au-Br-Au angle of 96.83(3)°.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300119
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  • 140
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    A Specific Route to Enantiomerically Pure Asymmetric (η6-Arene)(η4-1,5-cyclooctadiene)Ru(0) ComplexesDedicated to Professor Rolf Gleiter on the occassion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 123-130 
    Details
    ISSN: 0009-2940
    Keywords: Arene complexes ; Ruthenium compounds ; Electrophilic substitution ; Lithiation ; Catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral or achiral (arene)(COD)Ru complexes can be made by replacing the η6-ligands of (η4-1,5-COD)(η6-1,3,5-cyclooctatriene)Ru (1) or (η4-1,5-COD)(η6-naphthalene)Ru (2) by a suitable arene. This well known reaction has been extended to mono- and dibromoarenes and we report a novel route to substituted (arene)(COD)Ru species, utilizing (bromoarene)-(COD)Ru as starting materials. These facilitate a rapid bromine-lithium exchange reaction with nBuLi at low temperatures and the lithiated species react readily with alkyl chloroformates as electrophiles. By using chiral electrophiles [alkyl = (-)-menthyl] enantiomerically pure or diastereomeric complexes containing CO2R* groups are formed, depending on the symmetry of the original complex. A diastereomeric 1:1 mixture was separated by recrystallization. All (arene)-(COD)Ru complexes tested so far are useful as catalysts for the hydrogenation of simple alkenes at room temperature.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300121
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  • 141
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    Recent Advances in C-F Bond Activation (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 145-154 
    Details
    ISSN: 0009-2940
    Keywords: Fluorocarbons ; C-F bond activation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The main reaction pathways which lead to the breaking of C-F bonds in perfluoroalkanes and -arenes are discussed. Emphasis is placed on recent developments and on the mechanistic patterns that emerge.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300203
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  • 142
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    Metal Atoms in the Synthesis of Metal Clusters, VIII.On the Reaction of Sterically Demanding Cyclopentadiene Ligands with Cobalt Atoms: Synthesis, Crystal Structure, Spectroscopic Behavior, and Reactivity of Di-, Tri- and Tetranuclear Hydrido Clusters of CobaltDedicated to Professor IV Siehert on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 161-170 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metal-vapor reactions of Co atoms with 1,3-tBu2CpH (1a), 1,3-tBu2CpH (1a), 1,2,4-tBu3CpH (1b) and EtMe4CpH (1c) are described. With 1a the two mononuclear complexes [(η5-tBu2Cp) (η4-tBu2-1,3-cyclopentadiene)Co] (2a) and [(η5-tBu2Cp)2Co] (3a) were isolated, together with the dinuclear cobalt cluster [{(η5-tBu2Cp)Co}2H3] (4a) and trace amounts of the tetranuclear cluster [{(η5-tBu2Cp)CoH}4] (5a). The molecular structures of 3a and 4a were determined by X-ray diffraction. Reaction of 1b with Co atoms afforded a single product, the dinuclear cluster [{(η5-tBu3Cp)Co}2H3] (4b), whose molecular structure was determined by single-crystal X-ray diffraction. Both, 4a and 4b exhibit extremely short Co-Co distances [2.244(1) (4a) and 2.242(1) Å (4b)], as found for the Me5Cp analog [{(η5-Me5Cp)Co}2H3] (4c). Reaction of an isomeric mixture of Me4EtCpH (1c) with Co atoms furnished the mononuclear sandwich [ (η5-Me4EtCp)(η4-Me4Et-1,3- cyclopentadiene)Co] (2b), the trinuclear hydridocobalt cluster [{(η5-Me4EtCp)Co}3H4] (6a) and the tetranuclear hydridocobalt cluster [{(η5-Me4EtCp)Co}4H4] (5c). The molecular structure of 5c was determined by X-ray crystallography and revealed a tetrahedral arrangement of the cobalt atoms. The electrochemical behavior of the dinuclear complexes 4a-4c was studied by cyclic voltammetry. Reversible redox couples were found for all three compounds, with a correlation between the degree of alkyl substitution and their respective cathodic shifts. Compounds 4a and 4b react with CO to yield the mononuclear and dinuclear complexes [ (η5- CpR)Co(CO)2] (R=1,3-tBu2, 1,2,4-tBu3) (7a and 7b) as well as [{(η5-CpR)CO}2(CO)2] (8a and 8b). Reaction of the trinuclear hydridocobalt cluster 6a and its Me5Cp analog 6b with AgBF4 in the presence of PEt3 yielded the heteronuclear clusters [{η5-Me4CPR)Co}3AgP(Et)3H4]+[BF4]- (R=Et, Me) (9a and 9b). 9a was structurally characterized by X-ray crystallography.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300205
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  • 143
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    Generation and Synthetic Application of Metallated Methyl Isopropenyl Ether, A Substitute for Acetone Enolate (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 45-48 
    Details
    ISSN: 0009-2940
    Keywords: Metallated methyl isopropenyl ether ; Tetrahydrofurans ; 1-Oxabicyclo[4.3.0]heptanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl isopropenyl ether (1) has been metallated at low temperature with a 1:1 molar mixture of n-BuLi/t-BuOK in THF-hexane, and subsequently functionalized with a variety of electrophilic reagents. At temperatures higher than - 30°C, the metallated methyl isopropenyl ether (2) decomposes with formation of allene. When the suspension of 2 is allowed to warm up to room temperature in the presence of an additional equivalent of n-BuLi, the intermediary allene is converted into 1-propynyllithium (2c), which reacts with propylthiocyanate to give 1-propylthio-1-propyne (4). Some of the functionalization products were subjected to acidic hydrolysis affording the expected methyl ketones.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300107
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  • 144
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    Asymmetric Catalysis, 105Part 104: Ref.. Stereoselective Hydrogenation of Folic Acid with Immobilized Optically Active Rhodium(I)/Diphosphane Catalysts (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 55-62 
    Details
    ISSN: 0009-2940
    Keywords: Diastereoselective hydrogenation ; Folic acid ; Immobilized optically active rhodium(I)/diphosphane catalysts ; Leucovorin ; HPLC analysis of 5-formyltetrahydrofolic acid derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the hydrogenation of the C=N bonds in the pyrazine ring of the vitamin folic acid (1) optically active rhodium(I)/diphosphane complexes immobilized on supports such as silica gel or Al2O3 were used. The reduction was carried out at 50 bar hydrogen pressure in an aqueous solution buffered to pH 7. Thus, 5,6,7,8-tetrahydrofolic acid (2) was obtained which contains a new asymmetric center at C-6 of the pterine system. Therefore, in combination with the (S) configuration of the natural L-glutamic acid part of the molecule two diastereomers with (6S,S) and (6R,S) configuration arise. The relatively unstable tetrahydrofolic acid (2) was converted into its 5-formyl derivative folinic acid (4) by treatment with methyl formate/formic acid in a 5:1 mixture of DMSO/pyridine. The Ca salt of folinic acid (4) is the widely used drug leucovorin. The diastereomers were separated by silica gel HPLC. To the column bovine serum albumine (BSA) is covalently bound. With optically active rhodium(I)/diphosphane catalysts, immobilized on silica gel supports, a diastereoselectivity of up to 90% could be achieved in the hydrogenation of folic acid (1).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300109
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  • 145
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    Hexahydro-closo-hexaborane as a Ligand in Coordination Compounds: Syntheses and Crystal Structures of [M2(μ-bis-η3-B6H6)(PPh3)2] )M = Cu, Au) (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 405-408 
    Details
    ISSN: 0009-2940
    Keywords: Hexahydro-closo-hexaborates ; Boron ; Bridging ligands ; NMR spectroscopy ; Gold ; Copper ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By reaction of (PPh3)3 CuCl and PPh3AuCl with [B6H6]2- in organic media, dinuclear complexes are formed containing the hexaborate as a bridging ligand coordinated to the metal centers by opposite B3 facets of the B6 cluster in a trihapto mode. This is verified by single-crystal X-ray structural analysis of the isotypical (Paā) compounds [Cu2μ-bis-η3-B6H6)(PPh3)2] (1) and [Au2(μ-bis-η3-B6H6)(PPh3)2)] (2) which showed the metal centers to be very close to the B3 plane [1.92 (1), 2.10 (2) Å. The 11B NMR spectra of the two compounds feature doublets, at δ= -15.32 in 1 and at -11.51 in 2, which are significantly shifted downfield in comparison to [B6H6]2- (δ= -17.2).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300315
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  • 146
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    Crown Thioether Chemistry: Novel Silver(I) Complexes of 1,3-Dithiole-Annelated 1,4,7-Trithiacyclononane (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 425-429 
    Details
    ISSN: 0009-2940
    Keywords: Silver complexes ; Crown compounds ; Thioethers ; 1,3-Dithioles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The coordination chemistry of two crown thioethers 2,5,8,10,12-pentathiabicyclo[7.3.0]dodeca-1)9)-ene-11-thione (L) and -11-one (L') with Ag1 has been investigated by structural methods. Both thioethers act as tridentate ligands coordinating the silver ion in a trigonal fashion. In the case L, the 11- thione sulfur is coordinated additionally by another silver ion, to yield a polymeric chain with a distorted-tetrahedral geometry about the metal ion. Despite differing only in its carbonyl chalcogen, L' forms six-coordinated, monomeric complexes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300319
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    Unsymmetric Dinucleating Ligands for Metallobiosite Modelling (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 433-442 
    Details
    ISSN: 0009-2940
    Keywords: Metallobiosites ; Metalloproteins ; Metalloenzymes ; Dinucleating ligands ; Transition metals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Awareness of the asymmetric nature of numerous dinuclear metallobiosites and of the ability of the individual metal ions to have quite distinct roles in the functioning of the metalloenzyme concerned has led to a search for carefully designed unsymmetric dinucleating ligands that will give dinuclear complexes capable of acting as models for the metallobiosites. This review surveys progress made in the design and synthesis of complexes capable of serving as models for donor atom, coordination number and geometric asymmetries found at dinuclear metal centres.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300402
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  • 148
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    Chemie polyfunktioneller Moleküle, 125Part 124: Ref. Synthese und Kristallstruktur von N,N,N′,N“,N-Pentamethyl-diethylentriamin-cokoordiniertem Kalium-bis(diphenylphosphanyl)amidHerrn Prof. Dr. Gerhard Herberich zum 60. Geburtstage gewidmet. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 141-144 
    Details
    ISSN: 0009-2940
    Keywords: Alkali metal organophosphanylamide ; Carbon-potassium bonding ; Phosphazane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metalation of bis(diphenylphosphanyl)amine [HN-(PPh2)2,1 with KOtBu at 95°C in toluene affords a pale yellow precipitate of potassium bis(diphenylphosphanyl)amide (3a). On addition of liquid N,N,N′,N“,N“-pentamethyldiethylenetriamine (PMDTA, 4) the precipitate dissolves in toluene at 115°C to give a yellow solution, from which yellow-green blocks of [(Ph2P)2NK·PMDTA] (3b) are obtained. X-ray analysis reveals that the coordination sphere of potassium consists of the chelating triamine ligand and [N(PPh2)2]- as N-donor as well as η1 and η2 C-donor with two phenyl fragments. No phosphorus coordination of [N(PPh2)2]- is observed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300124
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    Organophosphorus Compounds, 114. Tetracyclic Phosphorus-Aluminium-Carbon Compounds - Synthesis by Cooligomerization of Kinetically Stabilized Phosphaalkynes with Trialkylaluminium CompoundsDedicated to Professor Michael Hanack on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 255-259 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaalkynes ; Triorganoaluminium compounds ; Cooligomerization ; Cage compounds ; Aluminium compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When the trialkylaluminium reagents 5 are allowed to react with phosphaalkynes 4 in n-pentane, a highly selective phosphaalkyne cyclotrimerization with incorporation of two organometallic units occurs (→ 6). The tetracyclooctane derivatives 6a-e represent the first examples of phosphorus-aluminium-carbon cage compounds. The polycyclic products 6 are able to function as ligands in transition-metal complexes (→ 7), which is illustrated by the reactions of 6b, c with nonacarbonyldiiron and pentacarbonyl(tetrahydrofuran)tungsten, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300219
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    On the Ligating Properties of Sulfonate and Perchlorate Anions Towards Zinc (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 283-289 
    Details
    ISSN: 0009-2940
    Keywords: Zinc ; Sulfonate ligands ; Perchlorates ; Coordination modes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attempts are reported to incorporate sulfonate and perchlorate anions as ligands in zinc complexes of tripodal ligands. Using tris(benzimidazolylmethyl)amine (BIMA) only the aqua complexes [ (BIMA)Zn-OH2](RSO3)(ClO4) and [(BIMA)Zn-OH2](RSO3)2(R=CH3, CF3, p-tolyl) were accessible. Using substituted pyrazolylborates (Tp*), the same three sulfonate anions were found to be ligands in the complexes Tp*Zn-OSO2R. Spectroscopic evidence for perchlorate coordination in Tp*ZnClO4 · 2 DMSO conflicts with crystallograpic evidence against it in Tp*ZnClO4 · pyridine. The crystal structures of [(BIMA)Zn-OH2](CH3SO3)2, TpCum,MeZn-OS02CH3, TPtBu,MeZn-OSO2C6H4-p-CH3, and [TpCum,MeZn · NC5H5]ClO4 were determined.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300223
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    Multiple Bonds Between Main-Group Elements and Transition Metals, CLXIV. Alkylrhenium(VI) Oxides-Synthesis and Characterization (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 295-298 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium ; Oxides ; Alkyl ligands ; Dirhenium compounds ; Metal-metal interactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Most alkylrhenium(VII) oxides, e.g. ((cyclo)-C3H5)Re03 (2) are rather sensitive to temperature and moisture with the prominent exception of methyltrioxorhenium (1). The corresponding alkylrhenium(VI) oxides of formula [RR′(O)- Re(μ-O)]2 [R=R′=(cyclo)-C3H5 (3), iPr (4); R=CH3, R′=C2H5 (5), R=CH3, R′=iPr (6)] are much more stable in this regard. They can be handled in air at room temperature. They were synthesized from Re207 and dialkylzinc precursors, fully characterized and are available in much higher yields than their ReVII congeners. Mixed tetraalkyltetraoxodirhenium(VI) complexes (R # R′) synthesized from 1 and dialkylzinc compounds form as a mixture of cis/trans isomers. They are oily liquids at room temperature. The Re=O and Re-Re stretching force constants as a measure of the bond strengths, were determined from IR and Raman data.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300225
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    Hydroxy- and Carboxy-Substituted Allylsilanes: A Simple and Stereoselective Method of Preparation (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 335-340 
    Details
    ISSN: 0009-2940
    Keywords: Allylsilanes ; Superbases ; Metalations ; Stereoselectivity ; Cyclizations ; Silicon ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When treated with two equivalents of a butyllithium/potassium tert-butoxide mixture, terminal olefins carrying unprotected hydroxy or carboxy groups generate allylmetal intermediates which can be trapped with chlorotrimethylsilane to afford functionalized (Z)-2-alkenyltrimethylsilanes. One equivalent of the superbasic reagent suffices if the unsaturated alcohols are first protected as acetals before being subjected to the metalation/silylation/hydrolysis sequence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300306
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    Preparation, Properties, and Reactions, of Metal-Containing Heterocycles, XCVIPart XCV: E. Lindner, E. Bosch, R. Fawzi, M. Steimann, H.A. Mayer, K. Gierling, Chem. Ber. 1996, 129, 945-951.. Mono-, Di- and Trinuclear Metallacycloalkanes of the Iron-TriadDedicated to Professor Wolfgang Beck on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 347-356 
    Details
    ISSN: 0009-2940
    Keywords: Metallacycloalkanes ; Metallacycloalkenes ; Osmium ; Iron ; Cyclic ketones ; Metallacycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the bis(triflates) [F3CSO3-(CH)m-O3SCF3] [m = 5-10, 12, 14, 16 (1a-i) with Na2[Os(CO)4] in dimethyl either affords the osmacycloalkanes 2a, 2b and 2f-i (m = 5, 6, 10, 12, 14, 16), diosmacycloalkanes 3a-i (m = 5-10, 12, 14, 16), and triosmacycloalkanes 4a-i (m = 5-10, 12, 14, 16). The structure of 3f was investigated by an X-ray structural analysis. This 22-membered disomacycle crystallizes in the space group Pā with Z = 1. If the unsaturated cis-4-octen-1,8-diyl bis(trifluoromethanesulfonate) (5) is treated with Na2[Os(CO)4] the diosmacyclooctadeca-5,14-diene 6 is obtained. By treating the bis(triflates) 1a, b with Na2[Fe(CO)4] the corresponding ferracycloalkanes are formed only in situ. Insertion of carbon monoxide into the M-C σ bonds leads to the cyclic ketones 7a, d and to the diketone 8d.
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    URL: http://dx.doi.org/10.1002/cber.19971300308
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    Enantioselective Catalysis, XIIIPart XII: U. Nagel, J. Leipold, Chem. Ber., 1996, 129815-821.. Preparative and Structural Chemistry of Chiral 3-(Diphenylphosphanyl)-pyrrolidiens and Their Palladium(II) Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 385-398 
    Details
    ISSN: 0009-2940
    Keywords: Pyrrolidinephosphanes ; 3-Hydroxypyrrolidine ; 3-Diphenylphosphanylpyronlidine ; Salt effects ; Polymorphism ; Homogeneous catalysis ; Palladium ; Asymmetric catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of both enantiomers of 3-diphenylphosphanulpyrrolidiine (2) and several N-substituted derivatives together with two PdIi complexes of this ligand is reported. Form L-malic acid and L-hydroxyproline both enantiomers of 3-hydroxypyrrolidine are prepared without any problems due to epimerization. KPPh2 in the presence of LiCl is shown to be the most effective reagent for the synthesis of 2. The reported X-ray structure determination sof Pdl2 complexes show a rather rigid bicyclic hetero-norbornane skeleton. The flexibility of the other parts of the molecules is obvious in several polymorphs revealed by this method. This polymorphism is additionally investigated by a 31P-CP-MAS study. From solution 1-, 13C- and 31P-NMR studies it is concluded that the bicyclic hetero-norbornane skeleton is retained in solution.
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    URL: http://dx.doi.org/10.1002/cber.19971300313
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  • 155
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    Reactions of Silicon-Silicon Bonds, VIFor part V, see ref.[1].. Reductive Trichloroslilylation Reactions Leading to Alkyl- and Dialkylaminobis(trichlorosilyl)phosphanesDedicated to Professor Walter Siebert on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 377-384 
    Details
    ISSN: 0009-2940
    Keywords: Trichlorosilylation ; Dichlorophosphanes ; Silylphosphanes ; Amino(silyl)phosphanes ; Silicon /Reductions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of hexachlorodisilane and of trichlorosilane/triethylamine with alkyl-and dialkylaminodichlorophosphanes RPCl2 1a-i [R = iPr: a; (Me3Si)2CH: b; R=1-adamantly: c: R=tBu: d; R=Et2N: e; R=iPr2M: f] furnish bis(trichlorosilyl)-phosphanes RP(SiCl3)2 3a-f. However, when less bulky substituents are attached to the phosphorus atom, so that there is little steric crowding, the double reductive silylations leading from 1 to 3 are accompanied by side reactions and decomposition of 3. Therefore, only 3b, 3c, 3d, and 3f wre isolated in a pure state. These compounds are more readily prepared by the; trichlorosilane/triethylamine method. 1H-, 31P- and 29Si-Nmr spectra confirm their constitution. The structure of solid 3f, the first aminobis(trichlorosilyl)phosphane, was determined by X-ray crystallography. 3f contains a phosphorus atom in a pyramidal environment surrounded by two silicon atoms and a planar nitrogen atom of the diisopropylamino group.
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    URL: http://dx.doi.org/10.1002/cber.19971300312
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    Formation of the Digallium Compound [(C5C6)2N3](R)Ga-Ga(R)[N3(C6H5)2] with Two Bis(trimethylsilyl)methyl Groups and Two Terminal Chelating Diphenyltriazenido Ligands (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 417-420 
    Details
    ISSN: 0009-2940
    Keywords: Gallium ; Low-valent compounds ; Gallium-gallium bond ; Terminal triphenytriazenido ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrakis[bis(trimethylsilyl)methyl]digallane (4) 1 reacts with 1,3-diphenyltriazene to yield two compounds, which were both characterized by a crystal structure determination. The gallium-gallium bond is retained in the yellow derivate [(H5C6)2N3](R)Ga-Ga(R)[N3(C6H5)2 2 [R = CH(SiMe3)2], which is formed by a ligand exchange reaction and shows two terminal chelating triazenido ligands besides two bis(trimethylsilyl)methyl groups; the Ga—Ga bond length is 245.79(6) pm. The second product is the orange dialkyl(diphenyltriazenido)gallium derivative R2Ga[N3(C6H5)2] 3, where the triazene has reacted as an oxidant by the cleavage of the Ga—Ga bond and probably by release of elemental hydrogen.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300317
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    The Electronic Structure of [Te15Br4][MoOBr4]2 and Some General Aspects of Bonding in “Classical” and Hypervalent Tellurium Halides (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 463-472 
    Details
    ISSN: 0009-2940
    Keywords: Hypervalent compounds ; Tellurium ; Polycations ; Molecular Orbital Theory ; Band structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Approximate MO and band structure calculation are used to analyze the bonding in the recently synthesized paramagnetic, semiconducting phase [Te15Br4]2+. The [Te15Br4]2+ chains are very similar to those in the tellurium subhalide Te2Br. The electronic structure and bonding within these chains is analysed and the possibility of hypervalency in both [Te15Br4][MoOBr4]2 and Te2Br is discussed. The bonding in the classically hypervalent molecule TeBr42- and a model Te3Br24- is compared to that of the infinite system. Our calculations indicate that both [Te15Br4][MoOBr4]2 and Te2Br contain weakly hypervalent Te atoms and that the interesting electronic properties of [Te15Br4][MoOBr4]2 arise within the distinct sublattices, which do not interact significantly.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300405
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    Heterobimetallic Complexes with a Propynylidene C3-Bridge: General Synthetic Routes to Bimetallic Ethynylcarbene Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 479-488 
    Details
    ISSN: 0009-2940
    Keywords: Heterobimetallic complexes ; Carbene complexes ; Alkynes ; Coupling reaction ; Bridging ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sequential reaction of the dimethylamino(trimethylsilylethylnyl)carbene complexes [(CO)5M'=C(NMe2)C≡CSiMe3] [M' = W (1a)] with KF/THFMeOH, nBuLi and transition metal halides, [XMLn], affords heterobimetallic propynyliden complexes of the type [(CO)5M'=C(N-Me2)C≡CMLn] [MLn = Ni(PPh3) Cp (4a, b). Ni(PMe2Ph)2- {Mes) (Mes=2,4,6-C6H2Me3) (5a), Rh(CO)(PPh3)2 (6a), Fe(CO)2Cp (7a,b)]. In contrast, reaction of 1a with MeLi · LiBr and [IFe(CO)2Cp] yields the novel N-metallated complex [(CO)5W=C{N(ME)Fe(CO)2Cp}C≡CSiMe3] (8a). The complexes [(CO)5M'=C(NMe2)C≡CMLn=Fe(CO)2Cp (7a, b), Ru(CO)2Cp (10a,b), Ru(CO)(PPh3)Cp (11a), Mn(CO)5 (12a), Re(CO)5 (13a)] are accessible by Pd-catalyzed coupling of the C-stannylated carbene complexes [(CO)5M'=C-(NMe2)C≡CSnBu3] (9a, b) with [XMLn]. The related monomethylaminocarbene complexes [(CO)5M'=C(NHMe)C≡ CSnBu3] (16a, b), obtained by stannylation of [(C))5M'=C(NHMe)C=CH] (15a, B) with Bu3SnNEt2, react with [IFe(CO)2Cp] to give the bimetallic complexes [(CO)5M'=C(NHMe)C≡CFe(CO)2Cp] (17a, b). The complexes 4a, 5a, 7a and 10a were characterized by X-ray structural analysis. The spectroscopic and structural data suggest that the two metal centers in 4-7, 10-13, and 17 interact only weakly.
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    URL: http://dx.doi.org/10.1002/cber.19971300407
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    Synthesis and Molecular Structure of a Rhenium Complex Derived from 8a-Amino-6-methyl-ergolineDedicated to Professor Roland Mayer on the occasion of his 70th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 839-841 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium ; Technetium ; 8a-Amino-6-methyl-ergoline ; Chelates ; Structure elucidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Current research in radiopharmaceutical chemistry is aimed at the design of technetium-based receptor-binding radiotracers because of the excellent nuclide properties of the isotope 99mTc. Tc tracers and the corresponding complexes of rhenium, as the inactive surrogate of Tc, are required to imitate organic agonists or antagonists of the receptor. We have started studies with ergolines, which are known to be dopamine substitutes. The present report deals with the functionalization of 8α-amino-6-methyl-ergoline (2) with a 2-mercaptoacetyl group, and the subsequent synthesis of the first rhenium complex containing a pendent ergoline moiety [Re- O(SSS)(RS)] (HSSSH = HS-CH2CH2-S-CH2CH2-SH and RSH = 8a-amino-N-(2-mercaptoacetyl)-6-methyl-ergoline) (4). The molecular structure of the rhenium complex was determined by X-ray crystal structure analysis.
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    URL: http://dx.doi.org/10.1002/cber.19971300705
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    Aminotroponimines as Ligands for Yttrium and Lanthanide Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 859-862 
    Details
    ISSN: 0009-2940
    Keywords: Yttrium ; Lanthanum ; Samarium ; Lanthanides ; Aminotroponiminate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of N-isopropyl-2-(isopropylamino)troponimine, [(i-Pr)2ATI]H, with KH in THF affords [(i-Pr)2ATI]K. This is a useful starting material for the preparation of the mono-, bis- and tris-substituted compounds [[i-Pr)2ATI]YCl2-(THF)2}2, [(i-Pr)2ATI2Y[O(2,6,t-Bu2C6H3)] and [(i-Pr)2-ATI]3Ln (Ln = Y, La, Sm), which can be obtained from ([i-Pr)2ATI]K and LnX3 and LnX3 (X = Cl, I), or Y[O(2,6-t-BuC6H3)]3. All compounds have been characterized by spectroscopic methods. The monosubstituted yttrium complex {[(i-Pr)2ATI]YCl2(THF)2}2 has also been investigated by single crystal X-ray diffraction.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300708
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    C-H Bond Activation of Simple Alkenes with (C5H5)CO Fragments: Preparation, Molecular Structure, and Dynamical Behaviour of Tri- and Tetranuclear Cyclopentadienylcobalt Cluster complexes with μ-Cycloalkyne Ligands (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 593-603 
    Details
    ISSN: 0009-2940
    Keywords: C-H activation ; Alkyne complexes ; Cyclopentadienyl cobalt ; Fluxionality ; Hydrido complexes ; Clusters ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vicinal C-H bonds of the cycloalkenes CnH2n (n = 5-8) were activated upon treatment under mild conditions with reactive sources of the (C5H5)CO fragment. With [C5H5)CO(C2H4)2] (2a), the trinuclear cluster complexes [H2((C5H5)CO)3(μ3-C2(CH2)n-2)] (5a: n = 5; 5c: n = 5d: n = 8) were formed. Using the more reactive [(C5H5)2Co]/K, 5a-5dwere obtained, along with small amounts of the tetranuclear [{(C5H5)CO}4r{μ4-C2(CH2)n-2}] (8a-c: n = 5-7). X-ray structure analyses of 5c, d and 8b, c were performed. A μ-‖ (orμ3-η1:η2:η1) coordination of the cycloalkyne ligands was found in the trinuclear cluster complexes. The tetranuclear 8b, c had the cycloalkynes quadruply bridging (μ4-η1:η2:η2:η1_ a butterfly arrangement of the metal atoms. The acetylenic carbon-carbon bonds are considerably lengthened upon coordination [1.392(4), 1.398(3) å in 5c d; 1.464(8), 1.499(5) Å in 8b, c]. Three dynamic processes - alkyne “walk” on top of the CO3 triangle, μ2-hydride migration, and μ2/μ3-hydride exchange - are operational in the trinuclear 5a-d. Dynamic NMR data for 5a are consistent with a “windshield-wiper” mechanism for the alkyne migration. Hydride exchange is associated with a higher energy barrier, and is probably and independent dynamic process.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300510
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    Organoamido- and Aryloxolanthanoids, 15Part 14: Ref. [1a].. Organometallic Compounds of the Lanthanoids, 116Part 115: Ref. [1b].. Syntheses of Low Coordination Number Divalent Lanthanoid Organoamide Complexes, and the X-ray Crystal Structures of Bis[(N-2,6-diisopropylphenyl)(N-trimethylsilyl)amido]bi(tetrahydrofuran)samarium(II)and -ytterbium(II) (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 409-415 
    Details
    ISSN: 0009-2940
    Keywords: Mercury ; Lanthanides ; Lanthanoid(II) complexes ; (N-2,6-Diisopropylphenyl)(N-trimethylsily)amide complexes ; Bis(trimethylsilyl)amide complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Mercury(II) amide complex Hg[N(SiMe3)(2,6-iPr2C6H3)]2 (1) was prepared by reaction of HgBr2 with Li[N(SiMe3) 2,6-iPr2C6H3)] in diethyl ether solvent. Redox transmetallation reactions of 1 with elemental samarium, europium or ytterbium in THF solvent (THF = tetrahydrofuran), generated the novel divalent complexes Ln[N(SiMe3)(2,6-iPr2C6H3]2(THF)2 with Ln = Sm (2), Eu (3) and Yb (4). 4 was also synthesized by reaction of elemental ytterbium, HgPh2 and HN(SiMe3)(2,6-Me3)2]2(THF)2 [Ln = Sm (5), Yb (6)] by reaction of the metals with HgPh2 and HN(SiMe3)2. Thermal desolvation of 4 under high vacuum gave Yb(N)(SiMe3)2,6-iPr2C6H3)]2 (THF) (7), whereas under identical conditions 6 yielded the solvent-free complex [Yb[N{SiMe3)2]2]2. (8). The new compounds 1-4 and 7 are hydrocarbon soluble and 171Yb-NMR spectra were recorded for 4, 6, 7 and 8. X-ray crystal structure determinations of 2 and 4 revealed four-coordinate, distorted tetrahedral metal environments augmented by weak Ln…ipso-C(aryl) interactions.
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    Synthesis and Structure of 2,2′ -Boryl-, Germyl-Silyl-, and Stannyl-Substituted 1,1′ -Binaphthyl SystemsDedicated to Professor Hans Paulsen on the occasion of his 75th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 923-932 
    Details
    ISSN: 0009-2940
    Keywords: Biaryls ; Boron ; Chirality ; Cooperative Effects ; Lewis acids ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of Lewis acid binaphthyl systems, substituted in 2-or 2,2′-position, are synthesized by lithiation of 2,2′-dibromo-1,l ′-binaphthyl (5), followed by addition of various electrophiles. Stepwise lithiation and subsequent borylation with trimethyl borate leads to the bromoboronic acid 6, which can be stabilized by esterification with pinacol giving 7. By increasing the reaction mixture to 2 equiv. of n-butyllithium and 2 equiv. of methyl borate the path to the binaphthylmonoboronic acid ester 9 is opened up. A further increase in the quantity of electrophile also leads to the binaphthylbisboronic acid ester 12. The 2,2′-disubstituted silyl, germyl, and stannyl derivatives 13a-15a are accessible in good yields. Treatment with boron halides leads exclusively to methyl/halogen exchange, giving the bidentate Lewis acids 13b-15b, the former of which can be bridged by oxygen.Only in case of the bis(tributylstannyl)binaphthyl 16a does ipso substitution occur in the presence of boron trichloride, giving the bis(dichloroboryl)-substituted binaphthyl 16b which can then be hydrolysed to 11. The structures of the majority of the compounds were investigated by X-ray diffraction. In case of the 2,2′-disubstituted compounds 13a-15a the naphthyl groups are orientated perpendicular to each other. The intra- and intermolecular interactions are dominated by this binaphthyl system. In case of the oxygenbridged compounds 13c and 14c the angle between the naphthyl planes decreases to about 70°. This also has an effect on the packing of the molecule; in this instance the orientation of two naphthyl in neighbouring molecules is nearly parallel. The structure of the diboronic acid is dominated by intra- and intermolecular hydrogen bonding.
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    Temperature-dependent Ring-Opening and -Closure of a Cyclic Phosphane-BoraneDedicated to Professor Gottfried Huttner on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 951-954 
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    ISSN: 0009-2940
    Keywords: Phosphane-boranes ; Medium-sized rings ; Ring opening and closure ; Temperature-dependent NMR studies ; Phosphorus ; Boron ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A phosphane-borane (3) with the P-B bond integrated into a seven-membered ring was prepared from 4-pentenyl-diphenylphosphane (4) by hydroboration using 9-borabicyclononane (9-BBN). The product was confirmed to have a ring structure in the solid state by single crystal X-ray diffraction. The P-B distance of 2.057(2) Å is indicative of a standard donor-acceptor bond similar to the type found in homologous five- and six-membered rings. The room-temperature 31P-NMR signal of the compound in various solvents (δ ≈ - 15) is not compatible with the cyclic structure and suggests that ring opening occurs as the compound is dissolved. Variable-temperature NMR work corroborated this assumption, and the enthalpy of ring closure was determined to be ΔH = -30.5(4) kJmol-l. In CD2C12 at -90°C, δ31P is shifted to +3.5 ppm to low field, suggesting virtually complete ring closure under these conditions.
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    The Coordination Chemistry of Fluorocarbons: Group-I and Group- II Metal Ion Complexes of Fluoro Macrocycles (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 963-968 
    Details
    ISSN: 0009-2940
    Keywords: Fluorine ; Macrocycles ; Complexes ; Sodium ; Barium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new fluoro macrocycles BenzoFN2O3 and F(N2O2)2C2H4 were synthesized in the reactions of 1,3-bis(bromomethyl)-2-fluorobenzene with benzo-diaza-15-crown-5 and 1,2-bis(diaza-12-crown-4)ethane, respectively, in 30% yield each. Close CF...metal ion interactions in the respective alkaline metal complexes in solution are evidenced by characteristic shifts of the 19F-NMR resonances of up to δ = 18.7 relative to the free ligand and by a decrease of the 1J(CF) coupling constant of up to 20 Hz, which is most pronounced in BenzoFN2O3 · Li+ and F(N2O2)2C2H4 · K+. In BenzoFN2O3· Li+ a1J(19F-7Li) of 15.5 Hz was observed, which is indicative very close CF...Li+ interactions in solution. In the X-ray crystal structures of BenzoFN2O3 · Na+ [CF⃛Na+ 246.8(2) pm], 26-fluoro-4,7,13,16-tetraoxa-1, 10-diazatricyclo[ 8.8.7.1 20,24 ] - hexacosa-20,22,24(26)triene · Na+ (CF⃛Na+ 267.1(2) pm) and 21 -fluoro-3,6,9,12,15,18-hexaoxabicyclo[ 18.3.1 1,20]heneicosa- l(24),20,22-triene. Ba2+ [CF⃛Ba2+ 299.0(3) pm] short CF⃛metal interactions were found. Such close CF⃛metal ion interactions do not result in a lengthening of the C-F bonds, which is not a sign of weak CF⃛metal ion interactions, since a Cambridge Structural Database search revealed that a shortening of the C-O bond length is also not observed in crown ether complexes of alkaline metals.
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    Organophosphorus Compounds, 118Part 2: 117: Ref1. Reactions of 1-Chloro-1H-phosphirenes with Nucleophiles (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 711-723 
    Details
    ISSN: 0009-2940
    Keywords: Phosphorus heterocycles ; 1H-Phosphirenes ; Nucleophilic substitution reactions at 1H-phosphirenes ; Metal-complexation of functionalized 1H-phosphirenes ; Carbonyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The halogen atoms in the 1-chloro-1H-phosphirenes, 5a-c, are easily substituted on reaction with organolithium and Grignard reagents, 14a-p, with formation of the corresponding O-, N-, C-, Si-, and Ge-substituted 1H-phosphirenes, 15a-t. C1/H exchange reactions also occur on reaction with lithium metal hydrides (5a → 17). Furthermore, substitution reactions are also realized with the alkali metal borates, 18a-g (→19a-g); the same is true for reactions with trimethylsilyl cyanide and azide (→22a-d). Some of the substitution products have been characterized in the form of their metal complexes, 16, 23, 24, and 25.
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    Synthesis of Germatranyl Derivatives of Esters of Carboxylic Acids via Organometallic (Si, Ge, Sn) Reagents (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 739-746 
    Details
    ISSN: 0009-2940
    Keywords: Germatranes ; Organotrihalogenogermanes ; Organometallic (Si, Ge, Sn) reagents ; Transmetallation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trialkylstannyl esters of tris(2-hydroxyalkyl)amines, N(CH2CHROSnAlk3)3 (9-11 (R = H, Me; Alk = Et, Bu), react with X3GeC(R1)(R2)COOR3 (12-17) (X = Cl or Br; R1, R2=H, Me, Ph, SiMe3, COOEt; R3=Me, Et) to give esters of α-germatranylcarboxylic acids, N(CH2CHRO)3GeC(R1)(R2)-COOR3 (1-8), in high yields. The synthesis of esters 12-17 is reported. Esters of α-germatranyldiphenylacetic acid 24 and 25 can be obtained by treatment of diphenylketene with Et3SnOMe to give in situ Et3SnC(Ph2)COOMe (23), followed by reaction with GeCl4 to give in situ Cl3GeC(Ph2)COOMe (22 and further reactions with 9 or 11, respectively. Reduction of germatrane 6 with LiAlH4 in diethyl ether leads to cleavage of the germanium-carbon bond with subsequent formation of (2-hydroxyethyl)trimethylsilane. The crystal structures of 3, 6 and 7 are reported. 1-Acyloxygermatranes 26 and 27 are obtained by treatment of 1-methoxygermatrane (28) with diphenyl- and dichloroacetic acid, respectively.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300611
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  • 168
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    Base-Induced Synthesis of a Tetrastannatriazabicyclo[3.1.1]heptane from Tris)dimethylchlorostannyl)amineDedicated to Professor W. Sieber on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 765-769 
    Details
    ISSN: 0009-2940
    Keywords: Tin - Nitrogen cage compounds ; Sn—X—Sn intramolecular bridges ; Distannylamine pyridine adduct ; Tin ; Moessbauer spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris(dimethylchlorostannyl)amine (2a) reacts with pyridine in a 3:4 molar ratio to produce the tin-nitrogen containing bicyclo[3.1.1]heptane (3) with elimination of the adduct Me2SnCl2·2 py. Treatment of the distannylamine 2,6-[Pr2H3N(SnMe2Cl)2 (4) with pyridine, however, leads to the formation of the 1:1 pyridine adduct 4 and this can be regarded as a model to explain the route to 3. The molecular structures of 3 and 5 were determined by multinuclear magnetic resonance spectroscopy in solution, as well as by X-ray structure analysis of their crystals. Typical structural features for both compounds are intramolecular Sn—X—Sn bridges. Support for the structures comes from MS fragmentation patterns, IR spectra, and the Mössbauer spectra.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300615
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  • 169
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    Thermal Reactions of 5-Alkylidene-4,5-dihydro-3H-1,2,4(λ3)-diazaphospholes (4-Phosphapyrazolines) - A Route to Various P—Heterocycles and to 2-PhosphabutadienesDedicated to Professor M. Hanack on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 779-788 
    Details
    ISSN: 0009-2940
    Keywords: 1,2,4-Diazaphospholes ; Phosphiranes, alkylidene- ; 2-Phosphabutadienes ; Phosphorus heterocycles ; pyrazolines, thermolysis ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 5-alkylidene-4,5-dihydro-3H-1,2,4(λ3)-diazaphospholes (4-phosphapyrazolines) are thermally much more stable than related compounds without the exocyclic double bond. Thermolysis reactions typically occur in the range 110-150°C in toluene solution, and different, mostly competing, reaction pathways are observed. Thermal extrusion of nitrogen from 8a-g gives rise to β-phosphanaylsiloxyalkenes 10, benzo[c]-phosphole derivatives 11, 14 and 115, (β-siloxyalkylidene)-Phosphiranes 12, and dihydro-1,3-oxaphospholes 13. The thermolysis of 5-alkylidene-4,5-dihydro-4-trimethylsilyl-3-trimethylsilyloxy-3H-1,2,4-dizaphospholes 17 afforded three products, including the highly substituted and stable 2-phosphabutadienes 18 formed by nitrogen extrusion and rearrangement. Finally, the 4-chloro-3-trimethylsilyloxy-substituted heterocycle 21 was transformed at 170°C into 4H-1,2,4-diazaphosphole 23. The structures of 13c and 18a were determined by single-crystal X-ray diffraction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300617
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  • 170
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    Reaction of 1,3-Dialkyl-4,5-dimethylimidazol-2-ylidenes with 2-Bromo-2,3-dihydro-1H-1,3,2-diazaboroles (Alkyl=iPr and tBu)Dedicated to professor Adolf Zschunke on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 705-710 
    Details
    ISSN: 0009-2940
    Keywords: Boron ; Diazaboroles ; Carbenes ; Heterocycles ; Imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Bromo-2,3-dihydro-1H-1,3,2-diazaboroles (3a-c) were synthesized by cyclocondensation of dilithiated 1,4-diazabutadienes (5a-c) with boron tribromide in hexane. 3a was also obtained by sodium amalgam reduction was conducted in ether solvents, diboroxane (2) resulted as the main product. Compound 3a and 1,3-dialkyl-4,5-dimethylimidazol2-ylidenes (6a, b) underwent halide displacement to afford the borolylimidazolium salts 7a, b. Compounds 2, 3a-c, and 7a, b were characterized by elemental analyses and spectroscopic methods (1H, 11B, 13C NMR; Ir; MS). The molecular structures of 2 and 7a were established by single-crystal X-ray diffraction analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300606
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  • 171
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    Well-Defined Metallodendrimers by Site-Specific Complexation (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 725-728 
    Details
    ISSN: 0009-2940
    Keywords: Dendrimers ; Metal complexes ; Nanostructures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Strong multiple complexation of transition metal ions, Cu(II), Zn(II) and Ni(II) with different generations of well-defined poly(propylene imine) dendrimers as multi(tridentate) ligands has been used to construct nanoscopic assemblies of defined structure and size incorporating a distinct number of metal ions from 2 up to 32.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300608
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  • 172
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    Compounds of Germanium and Tin, 2lPart 20: Ref.[1]. A Tetraaryldigermene with a Short Germanium-Germanium Double Bond and a Nearly Planar Environment of Both Germanium AtomsDedicated to Professor Hans Bürger on the occasion of his 6oth birthday (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 735-738 
    Details
    ISSN: 0009-2940
    Keywords: Germanium ; Digermenes ; Tin ; Germylenes ; Stannylenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of GeCl2 · dioxane with the Grignard reagent RMgBr (R=2-tBu-4,5,6-Me3C6H) furnishes the tetraaryldigermene R2Ge=GeR2 (8). X-ray structure-analysis of 8 reveals a short Ge=Ge double bond, a nearly planar environment of both germanium atoms and extremely widened C—Ge—C angles of 128°. In solution, 8 dissociates into two germylene molecules R2Ge, which can be trapped with oxygen or by [4+1] cycloaddition reactions with 1,4-dihetero-1,3-dienes. A similar cycloadduct of a stannylene wa obtained by thermolysis of (R′2Sn)3 (R′=2,4,6-iPr3C6H2), in the presence of a 1,4-diazabutadiene and characterized by an X-ray structure-analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300610
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  • 173
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    Synthesis and Crystal Structure of tert-Butylamino)di-tert-butyl)siliceniotrichloroaluminate, (Me3C)2Si=NCMe3·AlCl3, and Dimethylazomethine-Aluminium Trichloride, Me2C=NH·AlCl3Dedicated to Prof. A. Meller on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 753-755 
    Details
    ISSN: 0009-2940
    Keywords: Silicenium ion ; Iminosilane ; Aluminate ; Silicon ; Aluminium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithiated text-butylaminolfluorosilanes react with aluminum trichloride in ether, eliminating LiF to give AlCl3 adducts of iminosilanes  -  aminosiliceniotrichloroaluminates {R2Si-NCMe3·AlCl3}, which thermally form the dimethylazomethine- aluminium trichloride, Me2C=NH·AlCl3.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300613
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  • 174
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    Sulfur Compounds, 199Part 198: R. Steudel, Y Drozdova, K. Miaskiewicz, R. H. Hertwig, W. Koch, J Am. Chem. Soc. 1997, 119, 1990.. Novel Titanocene Thiolato Complexes and Their Application in Preparing New Sulfur-Containing Heterocycles (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 757-764 
    Details
    ISSN: 0009-2940
    Keywords: Titanocene complexes ; S ligands ; Organic polysulfanes ; Ligand transfer reactions ; Sulfur heterocycles ; Chalcogens ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of Cp2Ti(CO)2 (3) with the di- and polysulfanes 1,2,4-(CH2)2S3, C4S6 (9), C,7H10S3 (11), 1,2,4,6-(CH2)3S4 (16), C6H10S6(19), and S6 affords the titanocene chelate complexes Cp2TiS3(CH2)2 (8), (Cp2Ti)2C4S6 (10), Cp2TiS3C7H10 (13), Cp2TiS2C7H10 (14), Cp2TiS4(CH2)3 (17), Cp,2TiS6C6H6H10 (20), and Cp2TiS8 (23). 14 is also obtained from Cp2TiCl2 (1) and the geminal dithiol of norbornene. The analogous reaction with the dithiol of dicyclopentadiene yields Cp2TiS2C10H12 (15). In ligand transfer reactions, 8 reacts with SCl2 to give 1,2,3,5-tetrathiane (25), 10 provides 9 on reaction with Cl2, 13 when treated with S2Cl2 affords C7H10S5 (12), 15 reacts with S2Cl2Cl2 to give C10H12S4. 17 and SCl2 yield 1,2,3,5,7-pentathiepane (18), 20 is converted to C6H10S7 (22) on reaction with SCl2, and 23 yields S10 and 1,2,-C6H4(SCl)2, respectively. With phosgene, thiophosgene, and thionyl chloride, compound 15 yields the corresponding dithiocarbonate 26, the trithiocarbonate 27 and the trisulfane 2-oxide 28. The structure of 27 was determined by X-ray crystallography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300614
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  • 175
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    Synthesis of a Bisdienophilic Phthalocyanine and of Precursors for Repetitive Diels-Alder Reactions Based on Hemiporphyrazines and Phthalocyanines (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 801-806 
    Details
    ISSN: 0009-2940
    Keywords: Unsymmetrical phthalocyanines ; Hemiporphyrazines ; Macrocyclic bisdienes and bisdienophiles ; Diels-Alder reactions ; Ladder polymers ; Cycloaddition ; Macrocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The specific synthesis of a metal-free bisdienophilic phthalocyanine 193, suitable for repetitive Diels-Alder reactions, is reported. This was achieved by condensation of 191,3,3-trichloro-6/7-nitroioindolenine (191) and 4,9-dibutoxy-2,3,5,8-tetrahydro-1,3-diimino-1H-5,8-epoxybenz[f]isoindoline (2). The ability of 3 to undergo Diels-Alder reactions was tested by reaction with an excess of 1,2,3,4-tetraphenylcyclopentadienone (5). Experimental data of the hemiporphyrazines 9, 10, and 11, which can be used as precursors for the synthesis of ladder polymers, are also given in the Experimental Section.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300620
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  • 176
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    Pseudoelement Compounds, XPart IX: Ref. Synthesis and Crystal Structure of New Complexes of the Type trans-[Pt(H)X(PPh3)2 with Cyanamide and Cyanomethanide LigandsDedicated to Professor S. Engels on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1007-1012 
    Details
    ISSN: 0009-2940
    Keywords: Platinum ; Nitrocyanamide ; Nitrosodicyanomethanide ; 1,1,3, 3-Tetracyano-2-azapropenide ; 1,1,2,3,3-Pentacyanopropenide ; Hydrido complexes ; Coordination modes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new coordination compounds trans-[Pt(H)X(PPh3)2] with NCN- and C(CN)2-functionalized anions (X- = [N(O)C(CN)2]-, [NO2NCN]-, [N{C(CN)2}2]-, [NCC{C-(CN)2}2]-, have been characterized by 1H-, 31P-, 13C-NMR, and IR spectroscopy and elemental analyses the crystal structures of trans-[Pt(H)N(O)C(CN)2(PPh3)2], trans- [Pt(H)N{C(CN)2}2(PPh3)2], and trans-[Pt(H)NCC{C(CN)2}2-(PPh3)2) have been determined by X-ray diffraction. Remarkably, [N(O)C(CN)2]- is coordinated through the central nitrogen atom, while [N{C(CN)2}2]- and [NCC(C(CN)2]2]- are bonded through terminal nitrogen atoms of a C(CN)2 unit.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300730
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  • 177
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    New Coupling Reactions and Phosphorylations Using Organozinc Reagents (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1021-1027 
    Details
    ISSN: 0009-2940
    Keywords: Zinc ; Chirality ; Cross-coupling ; Phosphorylations ; Catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This Microreview on the chemistry of organozinc reagents starts by briefly showing the methods of preparation of organozinc compounds and then discusses the considerable synthetic utility of zinc organometallics for the formation of new carbon-carbon bonds in the presence of transition-metal catalysts. Finally, the use of organozinc chemistry for the preparation of polyfunctional and chiral phosphanes is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300802
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  • 178
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    Synthesis and Structures of Bis(tetramethylipiperidino)aluminum Halides-X-ray Crystal Structures of tmp2AlX (X = Cl, Br, I) and [tmp2A1(μ-F)l2 (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1047-1052 
    Details
    ISSN: 0009-2940
    Keywords: Bis(tetramethylipiperidino)aluminum halides ; Alkoxy((tetramethylpiperidino)aluminum halides ; 27Al-NMR spectra ; Aluminum ; Amides ; Synthetic methods ; Bridging ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Lithio-2,2,6,6-tetramethylpiperidine [Li(tmp)] reacts with AlX3 (X = Cl, Br) in diethyl ether/ n-hexane solution to generate the products of substitution and ether cleavage, [tmpAl(X)(μ-OEt)], (la, X = Cl; 1b, X = Br). However, when the reaction is allowed to proceed in n-hexane alone, an almost quantitative yield of compounds tmp2AlX (2a, X = Cl; 2b, X = Br; 2c, X = I) is obtained. According to 27AI-NMR spectroscopy, mass spectroscopy, cryoscopy, and X-ray crystal structure determinations, these compounds are monomeric in the solid state, in solution, and in the gas phase. 2b reacts with AgBF4 yielding the fluoride-bridged dimer (tmp2AlF), 2d, as shown by X-ray crystal structure determination.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300805
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  • 179
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    Synthesis, Structure, and Dynamic Behavior of (μ-Aldimido)(μ-η1: η2-alkyne)- biszirconocene Cation Complexes That Contain Planar-Tetracoordinate Carbon (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1069-1077 
    Details
    ISSN: 0009-2940
    Keywords: Planar-tetracoordinate carbon ; Dynamic organometallic systems, μ-alkyne complexes ; π-Agostic systems ; Zirconium ; Metallocenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The benzonitrile hydrozirconation product Cp2ZrCl(N—CHPh) 8 was treated with propynyl lithium to yield the (propynyl)(benzaldimido)ZrCp; complex 9. Subsequent treatment with trityl tetraphenylborate generated [Cp2Zr(C—C—CH3)-BPh-4] that instantaneously added to 9 to eventually form the (μ-aldimido)(μ-η1:η2-hexadiyne)ZrCp2 cation 11. The X-ray crystal structure analysis showed that 11 contains a planar-tetracoordinate carbon atom that is stabilized by forming a three-center-two-electron bond with the two adjacent metal atoms. Similarly, complex 9 reacted with [Cp2Zr(CH3)+CH3B(C6F5)3 1 to yield the planar-tetracoordinate carbon containing (μ-aldimido)(μ-η1:η2-2-butyne) Cp; cation 12. Both complexes 11 and 12 exhibit dynamic NMR spectra due to their rapid reorganization of the dimetallabicyclic frameworks (ΔG* = 10 kcal mol-1) in addition to an anchimerically assisted C—N bond rotation (ΔG* =15 kcal mol-1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300808
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  • 180
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    Isolation and Characterization of a Porphinatomanganese(IV) Complex from the Reaction of Dichloro Monoxide with 5,10,15,20-Tetrakis-(2,6-dichloropheny)porphinatomanganese(III) Chloride [Mn(EDCPP)CI] (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1099-1103 
    Details
    ISSN: 0009-2940
    Keywords: Porphyrinatomanganese(IV) ; Monooxygenase model ; Dichloro monoxide ; Catalytic alkene epoxidation ; Catalytic alkane oxygenation ; Catalytic alkane chlorination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The isolation at -78°C and characterization of the novel crystalline reactive porphinatomanganese(IV) complex Mn-(TDCPP)(OCl)2 (5) is described. 5 is compared with the porphinatomanganese(IV) complexes Mn(TDCPP)(C6H5IOCl)2 (2), Mn(TDCPP)(C6F510C1)CI (3) and Mn(TDCPP)(OCH3)2, (4). The stoichiometric reaction of 5 with triphenylphosphane yields 2.5 equivalents of triphenylphosphane oxide and 1.0 equivalent of Mn(TDCPP)Cl (1). Complex 5 epoxidizes stilbene, and oxygenates and chlorinates cyclohexane.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300811
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  • 181
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    Synthesis and Structure of Allenyl-Substituted η6-Benzene(tricarbonyl)-chromium Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1135-1139 
    Details
    ISSN: 0009-2940
    Keywords: Arene complexes ; Chromium ; Allenes ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cr(CO)3-complexed η6-phenylpropargylic alcohols 3 react in a displacement rearrangement with thionyl chloride or chlorodiphenylphosphane to give the chloro- or phosphoryl allenyl substituted η6-phenyl complexes 4 and 6, respectively. In the X-ray crystal structure of the novel organometallic allenic derivatives 4b and 6b the vicinal chloro or phosphoryl substituent and the benzene(tricarbonyl)chromium fragment are arranged coplanarily. Palladium/copper-catalyzed couplings of the chloroallene 4b with terminal alkynes disclose a facile access to ynallene derivatives 8, novel carbon-rich organometallic π-systems.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300816
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  • 182
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    Raman and Infrared Spectra and Quantum Chemical Calculations for Trichlorophosphoranylidenesulfamoyl Chloride, CISO2N=PCI3 (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1141-1145 
    Details
    ISSN: 0009-2940
    Keywords: Trichlorophosphoranylidenesulfamoyl chloride ; Vibrational spectroscopy ; Conformational properties ; Quantum chemical calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman (3500-50 cm-l) and infrared (4000-400 cm-l) spectra of the title compound, ClSO2N=PCl3, were recorded for the solid and liquid phase. Additionally, the Raman spectrum of the compound dissolved in CCl4 was obtained and qualitative depolarization values were determined. The spectra of the liquid and solid phase were interpreted in terms of the existence of only one conformation possessing C1 symmetry, as predicted by quantum chemical calculations. A complete vibrational assignment is proposed based on the relative intensities, on group frequencies along with support from the normal coordinate analysis. The experimental fundamental vibrational modes are compared to those obtained from theoretical approaches employing the ab initio MP2/6-31G* method and a density functional approximation (B3PW91/6-31G*).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300817
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  • 183
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    Ab Initio Studies on Disubstituted closo-Icosahedral Heteroboranes, X2B10H10 [X = CH, SiH, N, P, and Sb] (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1147-1150 
    Details
    ISSN: 0009-2940
    Keywords: Icosahedral heteroboranes ; Ab initio calculation ; Bonding models ; Aromaticity ; Nucleus Independent Chemical Shift [NICS] ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio theoretical studies on X2B10H10 (X = CH, SiH, N, P and Sb) have been done for all the three possible isomers. Unlike lower-vertex heteroboranes, all the hetero derivatives have shown similar trends in the relative stabilities, the 1,12-isomer being more stable followed by 1,7- and 1,2-isomers, except for N and Sb. No conventional 1,2-isomer for N could be found. Instead, a new nido isomer which is 18.1 kcal/mol higher in energy than the most stable isomer has been located. Any hetero group substitution to icosahedral R12H122- is found to be thermodynamically destabilizing. However, the Nucleus Independent Chemical Shift criterion shows that all compounds, except for 8, have similar aromaticity.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300818
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    The Molecular Structures of Triaminosilanes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1159-1166 
    Details
    ISSN: 0009-2940
    Keywords: Aminosilantes ; Structure elucidation ; Molecular conformations ; Configuration determination ; Nitrogen Planarity/Silanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structural chemistry of a series of triaminosilanes XSi(NR2)3 has been investigated in order to determine the ground-state configuration and conformation of these molecules. Theoretical studies and analogy with the isoelectronic XP(NR2)3 (X = CH2, O, Se, NSiMe3 etc.) and P(NR2)3 molecules suggest structures of Cs or C3 symmetry, with small energy differences between them. The molecular structure of HSi(NMe2)3 (1) has been determined by a single-crystal X-ray diffraction study at low temperature. Surprisingly, the molecules have a non-standard conformation with an irregular orientation of the three NMe2 groups. The hydrido-, chloro-, methyl-, and vinyltris(morpholino)silanes XSi[N(CH2CH2)2O]3 (X = H, Cl, Me, Vi; 2-5) were prepared from the corresponding chlorosilanes and morpholine (2, 3) or lithium morpholide (4,5). Their variable-temperature NMR spectra were studied and the molecular structures determined by single crystal X-ray diffraction. Compound 2 has a molecular geometry approaching mirror symmetry with one morpholino group significantly different from the other two. This structure resembles that of isoelectronic tris(amino)phosphines. Compounds 3-5 have structures with a propeller-like arrangement of the three morpholino rings approaching C3 symmetry for this part of the molecules. The chloro compound 3 shows the shortest Si-N bond lengths (average 1.690 Å), followed by 2 (1.708Å),5 (1.709Å) and 4 (l.712Å). The configuration of all nitrogen atoms is almost planar, with sums of the angles close to 360°, and the morpholino rings adopt a chair conformation. According to the solution NMR spectra the ring inversion is slow at low temperature, but the rings rotate freely about the Si-N bonds on the NMR time scale. The molecular structures are discussed in terms of steric and electronic effects of the substituents. Other model compounds, including (Me2N)3SiC6H4-4-Br (6), MeSi[N(CH2CH2)2NMe]3 (7) and PhSi[N(CH2)4]3 (8), could not be crystallized, but were characterized by their analytical and spectroscopic data.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300820
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    A Monomeric Bis(arena)lead(II) Complex with a Plumbocene-like Bent Sandwich Structural Unit  -  Structure of [Pb(1,2-C6H4Me2)2(AlCl4)2Dedicated to Professor C. G. Kreiter on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1731-1732 
    Details
    ISSN: 0009-2940
    Keywords: Lead ; Tetrachloroaluminate ; Arenes ; o-Xylene ; Bis(arene) Complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(o-xylene)lead(II) bis(tetrachloroaluminate), obtained from lead(II) chloride and aluminium trichloride in o-xylene, has been shown by X-ray crystallography to be a mononuclear lead complex with point group symmetry C2 The two aromatic ligands are arranged similarly to those in monomeric plumbocene. The coordination sphere is completed by two bidentate AlCl4-ions. The lead center uses about a quarter of its bonding capability for each of the four ligands
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301204
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  • 186
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    Titanium and Zirconium Complexes Containing a Novel Dianionic Trifunctional Amido Ligand (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1751-1759 
    Details
    ISSN: 0009-2940
    Keywords: Amido complexes ; Titanium ; Zirconium ; Alkylmetal compounds ; Amido complexes ; Titanium ; Zirconium ; Alkylmetal compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The novel tridentate diamidoamine ligands [RC(2C5H4N)(CH2NSiMe3)2)2- (R = H, CH3) have been synthesized and coordinated to TiIV giving the pentacoordinate complexes [MX2(RC(2-C5H4N)(CH2NSiMe3)2}] (M = Ti, Zr; X = Cl, Br). The crystal structure analysis of [TiBr2{HC(2-C5H4N)(CH2)2}] (M = Ti, Zr; X = Cl, Br). The crystal structure analysis of [TiBr2{HC(2-C5H4N)(CH2NSiMe3))] (10b) confirmed the involvement of the pyridyl function in the coordination to the meta centre occupying an apical position in the trigonal bipyramidal ligand polyhedron. alkylation of [TiCl2{H3CC(2-C5H4N)(CH2NSiMe3)2)] (12a) with one or two molar equivalents of [RMgCl](R = PhCH2, Me3SiC2) yielded the mono- and dialkyl complexes [TiClR{H3CC(2-C5H4N)(CH2NSiMe3)2)] and [TiR2(H3CC(2-C5H4N)(CH2NSiMe3)2)] and [TiR2(H3CC(2-C5H4N)(CH2NSiMe3)2}] in good yields. Depending on the steric demand of the alkyl group coordination or decoordination of the pyridyl group leads to four- or five-coordinate species. A crystal structure analysis of the pentacoordinate complex [TiCl(CH2SiMe3){H3CC(2-C5H4N)(CH2NSiMe3)2}] (16) was carried out.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301208
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  • 187
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    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301101
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  • 188
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    Cobalt Phthalocyanine Derivatives Supported on TiO2 by Sol-Gel Processing. Part 1: Preparation and Microstructure (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1585-1589 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanines ; Sol-gel processes ; Titanium alkoxides ; Supported catalysts ; Heterogenous catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cobalt(II) 2,9,16,23-tetrasulphophthalocyanine and cobalt(II) 2,9,16,23-tetra(chlorosulphonyl)phthalocyanine were supported on TiO2 by reaction of the phthalocyanines with Ti(OR)4 followed by sol-gel synthesis. The thus obtained solid materials are stable in sulfide-containing media and are therefore suitable as catalysts for HS oxidation. The structure of the samples was characterized by electron microscopy diffraction. The morphology of the matrix strongly depends on the cobalt phthalocyanine derivative. The pathalocyanines in the titania matrices are monomeric or dimeric depending both on the type of substituents of the CoPc derivative and on the titanium alkoxide used as precursors.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301106
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  • 189
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    Reversible Rearrangements of Chlorophosphane-Dichlorogermylene Ylides to Trichlorogermylphosphanes  -  Structure Determination of a Tetranuclear Bis(chlorophosphane)bis(trichlorogermylphosphane) Silver Bromide Complex (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1619-1623 
    Details
    ISSN: 0009-2940
    Keywords: Dichlorogermylene ; Trichlorogermylphosphanes ; Insertion ; Silver bromide complex ; Carbene homologues ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chlorophosphanes RR'PCl (1a: R,R' = 1b: R = tBu, R' = iPr, 1c: R = iPr, R' = Et2N, 1d: R = Et2N react with the dichlorogermylene dioxane complex 2 furnishing trichlorogermylphosphanes RR'PGeCl3 4a-d. In the cases of 1c/4c and 1d/4d the insertion reaction remain incomplete; similarly, 4a always contains, shortly after isolation in pure state, small amounts of 1a that can be detected by NMR. A provided by the reaction of trichlorosilylphosphane tBu(Et2N)PSiCl3 (5d) with GeCl4. The alkyl(dialkylamino) trichlorogermylphosphane 4d exists only in an equilibrium with chlorophosphane 1d, which coordinates GeCl2 leading to the dichlorogermylene complex 3d. A 1:1 mixture of 4a with 1a is formed by the novel cleavage (“chlorogermylation”) of the P-P bond of tetraisopropyldiphosphane with germanium tetrachloride. Di-tert-butyl(trichlorogermyl)phosphane 4e (R, R' = tBu) reacts with silver bromide providing a crystalline silver complex 7. A structure determination by X-ray diffraction reveals that 7 is [Ag4Br4(tBu2PCl)2(tBu2PGeCl3)2]. 2C7H8. Two of the Ag atoms of the cubane-like (AgBr)4 core of 7 are coordinated by chlorophosphane 1e, the other two by trichlorogermylphosphane 4e.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301110
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  • 190
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    Formation of the Cationic [(2-Aminoethenyl)carbine]iron Complexes by Treatment of (2-Methoxyethenyl)carbene Complexes with Primary Amines:Synthesis and Characterisation (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1647-1654 
    Details
    ISSN: 0009-2940
    Keywords: Iron ; Carbene complexes ; (2-Methoxythenyl)methoxycarbene complexes ; Aminolysis ; (2-Aminoethenyl) methoxycarbene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cationic (2-methoxyethenyl)methoxycarbene iron complexes 2, [Cp(CO)2Fe(C(OMe)CH=CR(OMe))+][PF6-], are obtained by the addition of methanol to the corresponding (alkynyl)-methoxycarbene complexes 1, [Cp(CO)2Fe(C(OMe)C≡CR)+][PF6-]. Primary amines, H2NR', react with these 1,3-dimethoxy-substituted (alkenyl)carbene complexes, 2, through an addition/elimination process to yield cationic (2-aminoethenyl)methoxycarbene iron complexes, 3, [Cp(CO)2Fe(C(OMe)CH=CR(NHR'))+][PF6-] in an isolated yield of 71-90%. The complexes 3a-c were characterized by X-ray structural analyses. Thus, previously isolated products, from the reaction, of the (alkynyl)methoxycarbene complexes 1a and 1c, with aniline at room temperature, are assigned to the structures 3c and 3e. The spectroscopic and structural data obtained are discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301115
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  • 191
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    1-Hexene Hydroformylation with the Rhodium (I) Triphosphane Complex [Rh(CO){PhP(CH2CH2PPh2)2}]PF6: An In Situ Study Using High-Pressure NMR Spectroscopy (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1633-1641 
    Details
    ISSN: 0009-2940
    Keywords: Hydroformylation ; High-pressure NMR ; Homogeneous catalysis ; Rhodium ; Polyphosphane ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rhodium-catalyzed hydroformylation of 1-hexene in THF with the linear triphosphane PhP(CH2CH2PPh2)2 [PP,] has been studied both in situ and in high-pressure autoclaves. Sapphire NMR tubes with titanium valves have proved useful for studying the in situ reactions under conditions of relatively high syngas pressure (30-90 atm H,/CO) and temperature (60-100 C). Under conditions conducive to effective hydroformylation, the catalyst precursor [ (PP,)Rh(CO)]+ is quantitatively converted to the dicarbonyl [ (PP,)Rh(CO),]+, which is also the termination product of the catalysis. Irrespective of the syngas composition and of the total pressure, the dicarbonyl complex is the only phosphorus-containing species detectable on the NMR time-scale during the course of the isomerization and hydroformylation of the alkene. The PP2-Rh catalytic system exhibits some peculiar features that may be summarized as follows. (i) Very high partial pressures of CO (120 atm) neither inhibit the hydroformylation nor affect the n/i selectivity; (ii) alkene hydrogenation occurs neither at very high partial pressures of H, (120 atm) nor in the absence of added CO; (iii) the isomerization rate is slightly faster than that of hydroformylation; (iv) terminal and internal alkenes (2-, 3-hexenes) are hydroformylated with comparable rates. Various control experiments have been carried out using in-situ NMR, as well as batch experiments under different reaction conditions or with different catalyst precursors. Despite these extensive studies, unambiguous conclusions about the catalysis mechanism have not been reached. In particular, the possibility that different catalysts may be operative depending on the reaction conditions cannot be ruled out. The hydroformylation results rule out the involvement of phosphane-free “Rh-CO” catalysts, even under conditions of very high partial pressure of CO, and point to “(PP,)Rh(CO),” catalysts with small steric hindrance over the whole range of syngas pressures investigated.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301113
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  • 192
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    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301201
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  • 193
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    Coordination Chemistry of PentahalocyclopentadienylsThis article is dedicated to Professor Wolfgang Beck on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1721-1730 
    Details
    ISSN: 0009-2940
    Keywords: Perhalometallocenes ; Cylopentadienes ; Perhalogenated ; Halogen-metal exchange reactions ; Sandwich complexes ; Ligand effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The coordination chemistry of perhalocyclopentadienyl ligands, first developed in the early 1970's as a part of a research program directed towards the synthesis of oxidation-resistant fuel additives, has been revived in the last ten years. This renewed interest stems from the discovery that the coordinated cyclopentadienyl ligand allows multiple functionalizations. Thus, the high versatility of this important class of ligands can be broadened even further, which may be important with regard to industrial applications of metallocenes.
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    URL: http://dx.doi.org/10.1002/cber.19971301203
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  • 194
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    Density Functional Studies on Amino-Substituted Methane and Silane (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1745-1749 
    Details
    ISSN: 0009-2940
    Keywords: Density functional calculations ; Tetra(amino)methane ; Tetra(amino)silane ; Transition states ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In all-electron density functional calculations on mono- and tetraaminosubstituted methane and silane the coordination around the nitrogen center is found, in complete agreement with experiment, to be less pyramidal in the silicon compounds. The calculated barrier to inversion at nitrogen is only 0.6 kcal/mol in silylamine, while in methylamine it is 5.5 kcal/mol. The larger flexibility is attributed to the greater ionic character of the Si-N bond compared to that of the C-N bond. In tetra(amino)methane, inversion of one amino group leads to a local minimum (calculated inversion barrier: 6.4 kcal/mol), while a corresponding structure (or barrier) does not exist for the silicon compound. Due to the steric influence of the amino groups, the barrier to rotation around the C-N bond is larger in the tetrasubstituted compound (6.4 kcal/mol compared to 2.3 kcal/mol in methylamine). While the average binding energy of the amino groups is similar in both tetra(amino)compounds, the binding energy of the fourth ligand is about 25% larger in the silicon compound for both homolytic and heterolytic bond cleavage. This difference arises from the relative stabilization of the tri(amino)-methyl species, due to some n contribution to the C-N bond.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301207
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  • 195
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    Phosphanyl-Substituted Phosphaferrocenes as p,p-Chelate Ligands (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1771-1776 
    Details
    ISSN: 0009-2940
    Keywords: Chelates ; P ligands ; Phosphaferrocene ; Carbonyl complexes ; Heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dicyclohexyl-acid diphenylphosphanyl-substituted phosphaferrocenes 2 and 3 were synthesized by substitution of the amino group in 2-dimethylaminomethyl-3,4,-dimethylphosphaferrocene 1 · Homologization of 2-formyl-3,4-dimethylphosphaferrocene 4 by one CH2 unit via Wittig olefination provided access to the phosphanylethyl derivative 9. Ligands 2, 3 and 9 formed P, P-chelate complexes with tetracarbonyl metal fragments in good yield. X-ray crystal structure determinations were carried out for the five-ring chelate complex 2. Mo(CO)4 (≡ l0), and the six-ring chelate complex 9 . Mo(CO)4, (≡ 13).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301211
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  • 196
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    A Structural Study of Selenobenzamides: Crystal Structures and Dynamic 13C NMR (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 49-54 
    Details
    ISSN: 0009-2940
    Keywords: 4-(p-Bromoselenobenzoyl)morpholine ; 4-[(p-(Dimethylamino)selenobenzoyl]morpholine ; Hindered rotation ; Hammett treatment ; Selenoamides ; Amides ; Selenium compounds ; Structure elucidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solid-state structures of (p-bromoselenobenzoyl)morpholine (2a) and [p-(dimethylamino)selenobenzoyl]morpholine (2b) were determined by X-ray diffraction. Both molecules show a flat selenoamide group. The larger contribution of resonance stabilization by the aromatic ring carrying the p-dimethylamino substituent is reflected by the smaller interplanar angle Θ between the aromatic ring and the selenoamide group [53.3(1)° vs. 81.1(1)°] and by the shorter length of the C=Se bond [1.824(5) Å vs. 1.840(3) Å]. The Gibbs free energy of activation of C-N bond rotation (ΔG≠rot) of five p-substituted (selenobenzoyl)morpholines was determined by dynamic 13C NMR. The activation barriers were found to range from 61.6 kJ/mol (X = NNMe2) to 75.1 kJ/mol (X = H). The ΔG≠rot values of the corresponding (thiobenzoyl)morpholines were found to be from 3.2 kJ/mol (X = NMe2) to 5.0 kJ/mol (X = H) lower. In both cases, ΔG≠rot showed an excellent linear Hammett correlation with s̰+p.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300108
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    A Theoretical Investigation of Cycloadditions of Hydrogen Isocyanide to CH2=X and PH=X Dipolarophiles (X = CH2, NH, O, SiH2, PH, S)We dedicate this paper to the memory of our friend and colleague, Prof. Dr. Gerrit L'Abbé, who untimely passed away on August 27, 1996. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 69-76 
    Details
    ISSN: 0009-2940
    Keywords: [2 + 1] Cycloadditions ; Hydrogen cyanide ; Phosphorus dipolarophiles ; Three-membered rings ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We performed a systematic investigation of [2 + 1] cycloadditions of HN≡C to dipolarophiles of the type CH2=X and PH=X with X=CH2, NH, O, SiH2, PH, and S, as well as HN=NH and H2Si=SiH2. Ab initio MO calculations at the QCISD(T)/6-311G(d,p)/MP2/6-31G(d,p)+ZPE level were applied to construct the minimum-energy reaction pathways. Calculated results concerning the regiochemistry of the approaches and the stereochemistry of the product formation were analyzed in relation with established concepts such as frontier orbital, net charge distribution and stereoelectronic effect. For some systems, up to four distinct transition structures for cycloaddition were found. In general, there is a certain similarity between the behavior of both C and P series of dipolarophiles. The characteristics of the transition structures can be, in most cases, recovered by using qualitative concepts. The [2 + 1] cycloadditions are highly regioselective and stereospecific. Silicon-containing dipolarophiles are particularly attractive as they exhibit very small energy barriers to addition to isocyanides.
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    URL: http://dx.doi.org/10.1002/cber.19971300111
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    Triphenylphosphonio-Substituted 1,2,3,4-Triazaphospholes and 1,2,4-Diazaphospholes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 89-94 
    Details
    ISSN: 0009-2940
    Keywords: (Triphenylphosphonio)phosphaethyne ; Azides ; [3 + 2] Cycloadditions ; Phosphonio-1,2,3,4-triazaphospholes ; Diphosphonio-1,2,4-diazahospholes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several products resulting from the condensation of the bis-(trimethylsilyl)ylide 1 with PCl3 serve as synthetic equivalents of a phosphoniophosphaethyne. Cycloaddition reactions with azides lead to phosphonio-1,2,3,4-triazaphosphole cations 5, 7 and to the zwitterionic phosphonio-1,2,3,4-triazaphospholide 6. The latter readily undergoes a cycloreversion yielding a phosphoranediyl diazomethane 12 as intermediate. Its cycloaddition affords the diphosphonio-1,2,4-diazaphosholide chloride 9a as the final product. 9a is a remarkably stable and unreactive derivative of the two-coordinate phosphorus. By HCL it is protonated at a nitrogen atom to give dication without any tendency to associate with the chloride counterions.
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    URL: http://dx.doi.org/10.1002/cber.19971300114
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    Tris(phenylthiomethyl)phosphane Sulfide and Selenide, (PhSCH2)3PX (X = S, Se), as Ambidentate Ligand Systems in Copper(I) Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 105-110 
    Details
    ISSN: 0009-2940
    Keywords: Sulfides ; Selenides ; Copper complexes ; Ambidentate ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triphenylphosphite has been converted into tris(phenylthiomethyl)phosphane (1) by reaction with LiCH2SPh/DABCO, and subsequently into the corresponding sulfide (2) and selenide (3) by treatment with elemental sulfur or selenium, respectively. Ligands 2 and 3 react with copper(I) halides CuX (X = Cl, Br, I) in polar organic solvents to give either 1:1 (X = Cl: 4, 7, X = Br: 5, 8 ) or 1:2 complexes (X = Br: 9, X = I: 6, 10). The crystal structures of five of these complexes have been determined by single crystal X-ray diffraction studies. All compounds of the type [(PhSCH2)3P=S/Se]CuX (X = Cl, Br) form centrosymmetrical dinuclear complexes featuring a four-membered ring core Cu2[S/Se], fused to two five-membered rings Cu[S/Se]PCS through common trans edges. Only one of the three phenyl-thiomethyl functions is involved in coordination to a metal center. The compound [(PhSCH2)3P=S](CuI)2 (6) is associated into a centrosymmetrical tetranuclear complex containing two four-membered rings (ICu2S) bridged via iodine atoms in 1,3-cis positions. The ligand is found to employ two of its PhSCH2 functions for metal coordination, giving rise to two five-membered rings fused to the four-membered rings via neighbouring edges. In all cases, therefore, the P=S/Se functions of the ligands are the preferred donor sites, which are used for the building of bridgehead structural units of polynuclear complexes.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300117
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  • 200
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    Bildung und Charakterisierung des Dinatrium-tetraphosphendiids (tBu3Si)NaP-P=P-PNa(SitBu3) und seines Dimeren (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 135-140 
    Details
    ISSN: 0009-2940
    Keywords: Synthesis ; Phosphorus ; Supersilyloligophosphides ; Crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of P4 in THF or DME with 2 R*Na (R* = SitBu3) at -78°C leads quantitatively to deep red THF or DME adducts of R*NaP-P=P-PNaR* (3). According to 31P NMR, the P4 skeleton 3 is cis-configurated. On the other hand, reaction of P4 in TBME with 2 R*Na at -78°C leads quantitatively to (R*NaP)4 (4), a [2+2] cycloadduct of 3, the Na4P8 skeleton of which according to X-ray structure analysis forms a double cube with four P atoms in the second layer and two P and two Na atoms in alternating positions in the first and in the third layer (the Na atoms are coordinated with donors). By resolving the THF adduct 3 in TBME (the TBME adduct of 4 in THF) the compound 4 (the compound 3) is rapidly formed under reversal of the P-P=P-P configuration by way of [2+2] cycloaddition (by way of [2+2] cycloreversion). 3 and 4 are sensitive to oxidation and to protolysis. With TCNE, 3 is oxidized to R*2P4 (bicyclic P4 skeleton), with CF3SO3H, 3 may be transformed into R*3P5Na2 X 4 THF or in (R*P3)3 and R*PH2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300123
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