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  • Articles: DFG German National Licenses  (51)
  • 1995-1999  (51)
  • Inorganic Chemistry  (47)
  • crystal structure  (10)
  • Chemotherapy  (4)
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  • Articles: DFG German National Licenses  (51)
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  • 1
    Electronic Resource
    Electronic Resource
    [Gd4(C2)](Cl, I)6, an Interstitially Stabilized Heteroleptic Gadolinium SesquihalideDedicated to Professor John D. Corbett on the Occasion of his 70th Birthday (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 494-500 
    Details
    ISSN: 0044-2313
    Keywords: Gadolinium sesquihalide ; interstitial carbon units ; crystal structure ; electronic structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [Gd4(C2)](Cl, I)6, ein interstitiell stabilisiertes, heteroleptisches Gadoliniumsesquihalogenid[Gd4(C2)](Cl, I)6 erhält man aus CsI, Gd, GdCl3 und C2I4 in verschweißten Niob-Ampullen bei 1000/800°C in Form von schwarzen, glänzenden Nadeln. Die Kristallstruktur (tetragonal; P4/mbm; Z = 2; a = 1347,5(1); c = 1212,5(1) pm) ist ähnlich wie jene von Na[Mo4]O6 bzw. [Sc4B]Cl6. Trans-kantenverknüpfte [Gd6]-Oktaeder verlaufen parallel [001]. Sie enthalten interstitielle C2-Einheiten, Jedes dritte Oktaeder enthält fehlgeordnete C2-Einheiten, senkrecht zu jenen in den benachbarten [Gd6(C2)]-Oktaedern. Diese sind daher entlang der (pseudo)-C4-Achse gestaucht. Rechnungen zur elektronischen Struktur zeigen, daß insgesamt 13 Elektronen zur Auffüllung aller Metall-Metall-bindenden Zustände für eine „leere“ [Gd4]Cl6-Struktur nötig wären. Die Einlagerung der C2-Dimeren verändert die Bindungsverhältnisse in [Gd4(C2)]X6 (X = Cl, I) erheblich. Die formale Ladung von -6 der C2-Einheit wird durch das Aufsplitten der πg-Zustände reduziert, Gd—Gd und Gd—C-bindende Zustände werden besetzt und bindende dx2-y2-Orbitale kombinieren zu den am niedrigsten liegenden nicht besetzten Zuständen.
    Notes: [Gd4(C2)](Cl, I)6 is obtained from CsI, Gd, GdCl3 and C2I4 in sealed niobium containers at 1000/800°C as black, shiny needles. The crystal structure (tetragonal, P4/mbm, Z = 2, a = 1347.5(1), c = 1212.5(1) pm) is similar to that of Na[Mo4]O6 and [Sc4B]Cl6. It may be regarded as being built from octahedra sharing common trans edges running in the [001] direction. The octahedra contain C2 units as interstitials. Every third octahedron contains a disordered C2 unit perpendicular to those in the two neighboring [Gd6(C2)] octahedra and is therefore compressed in the direction of the (pseudo) C4 axis. Calculations of the electronic structure of an “empty” [Gd4]Cl6 structure reveals a total of 13 electrons necessary to occupy all metal-metal bonding states. The incorporation of a carbon dimer substantially alters the bonding conditions for [Gd4(C2)]X6 (X = Cl, I). The formal charge of -6 of the C2 unit is significantly reduced as πg states split up, Gd—Gd and Gd—C bonding states are occupied and bonding dx2—y2 orbitals combine to form the lowest unoccupied energy states.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966220318
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  • 2
    Electronic Resource
    Electronic Resource
    Sphincter preservation with chemoradiation in anal canal carcinoma (1998)
    Springer
    Diseases of the colon & rectum 41 (1998), S. 441-450 
    Details
    ISSN: 1530-0358
    Keywords: Anal canal cancer ; Combination therapy ; Radiation ; Chemotherapy ; MIB1 ; Ploidy ; Prognostic factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: This study contained herein assessed long-term results, toxicity, and prognostic variables following combined modality therapy of patients with International Union Against Cancer Classification T1–4, N0–3, M0 squamous-cell carcinoma of the anal canal. PATIENTS AND METHODS: Between 1985 and 1996, 62 patients completed treatment with combined modality therapy. A median total dose of 50 Gy was given to the primary, perirectal, presacral, and inguinal nodes followed by a local boost in selected cases. 5-Fluorouracil was scheduled as a continuous infusion of 1,000 mg/m2 per 24 hours on days 1 to 5 and 29 to 33 and mitomycin C as a bolus of 10 mg/m2 on days 1 and 29. Routinely processed paraffin-embedded sections were stained using monoclonal antibodies for detection of proliferating cell nuclear antigen and MIB1 (Ki-67) antigen to determine the labeling index. In addition, DNA ploidy was assessed after Feulgen staining. RESULTS: Actuarial cancer-related survival, no evidence of disease survival, and colostomy-free survival rates at five years were 81, 76, and 86 percent, respectively. In univariate analysis, T category (T1/2 vs. T3/4) was predictive for no evidence of disease survival (87vs. 59 percent;P=0.03) and colostomy-free survival (94vs. 73 percent;P=0.05). N category (N0vs. N1–3) influenced actuarial cancer-related survival (85vs. 58 percent;P=0.002) and no evidence of disease survival (80vs. 53 percent;P=0.02). A higher proliferative potential as measured by the MIB1 labeling index was associated with a better colostomy-free survival (90vs. 50 percent;P=0.04). In multivariate analysis, actuarial cancer-related survival was only influenced by the N category (P=0.03) and no evidence of disease survival by N category (P=0.03) and mitomycin C dose (P=0.04). Salvage abdominoperineal resection achieved long-term control in only four of seven patients with local failures. CONCLUSION: Treatment with a combination of radiotherapy and chemotherapy is safe and effective for patients with anal canal carcinoma. Abdominoperineal resection is indicated as a salvage procedure in nonresponding and recurrent lesions and may be of benefit in a small subgroup of patients with poor prognostic factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02235757
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  • 3
    Electronic Resource
    Electronic Resource
    Tandem and triple high-dose chemotherapy with autologous stem cell rescue in metastatic breast cancer (1998)
    Springer
    Journal of cancer research and clinical oncology 124 (1998), S. 690-694 
    Details
    ISSN: 1432-1335
    Keywords: Key words Breast cancer ; Chemotherapy ; Transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this phase II study was to evaluate the therapeutic efficacy and toxicity of a tandem or triple high-dose chemotherapy (HDC) with autologous peripheral blood stem cell transplantation (PBSCT) in patients with metastatic breast cancer (MBC) as first line chemotherapy. Conventional chemotherapy consisted of two cycles of epirubicin 120 mg/m2 and ifosfamide 7500 mg/m2 in the case of tandem HDC and one cycle of paclitaxel 135 mg/m2, epirubicin 90 mg/m2 and ifosfamide 6000 mg/m2 in the case of triple HDC. Tandem HDC was composed of two cycles of epirubicin 180 mg/m2, ifosfamide 12000 mg/m2 and carboplatin 900 mg/m2. In the case of triple HDC, paclitaxel 180 mg/m2, etoposide 1500 mg/m2 and thiotepa 600 mg/m2 was added as the third cycle. Patients with tandem HDC (n = 20) were evaluable for both survival and toxicity, and patients with triple HDC (n = 21) only for toxicity because of short-term follow-up. Both tandem and triple HDC were well tolerated and could be safely administered. Non-hematological WHO grade 3 or 4 toxicities were mucositis (8), temporary renal insufficiency (1), myocardial infarction (1), and neuropathy (1). No toxic death occurred. The Kaplan-Meier estimates for 44-months without progression and the overall survival were 12% and 38% respectively. The median survival was 22 months (95% CI: 7.4–51.7 months) and the median progression-free interval 14 months (95% CI: 5.1–43.7 months). In a population with an unfavorable prognosis, tandem HDC showed similar efficacy as to that described in other phase II studies. Triple HDC seems not to improve patient outcome compared to tandem HDC, but a long-term follow up is required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004320050233
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  • 4
    Electronic Resource
    Electronic Resource
    Merkel-Zell-Tumor oder neuroendokrines Hautkarzinom (1997)
    Springer
    Langenbeck's archives of surgery 382 (1997), S. 349-358 
    Details
    ISSN: 1435-2451
    Keywords: Key words Merkel cell carcinoma ; Surgery ; Radiotherapy ; Chemotherapy ; Pathology ; Prognosis ; Therapeutic outcome ; Recurrence ; Schlüsselwörter Merkel-Zell-Karzinom ; Chirurgie ; Strahlentherapie ; Chemotherapie ; Pathologie ; Prognose ; Therapieergebnis ; Rezidiv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der Merkel-Zell-Tumor ist ein maligner Hauttumor von neuroendokriner Differenzierung. Er befällt vorwiegend ältere Menschen. 78,6% der Patien-ten sind älter als 59 Jahre. Bis zum 60. Lebensjahr sind beide Geschlechter gleichermaßen betroffen. Ab dem 60. Lebensjahr überwiegt das weibliche Geschlecht. Der Tumor ist am häufigsten im Kopf-Hals-Bereich (50,8%) und an den Extremitäten (33,7%) lokalisiert und hat zum Zeitpunkt der Diagnosestellung eine durchschnittliche Größe von 29 mm. Bei 30% der Patienten liegen bereits bei der Erstvorstellung klinisch positive regionale Lymphknoten vor. Klinisch ist eine definitive Diagnosestellung nicht möglich. Eine lichtmikroskopisch geäußerte Verdachtsdiagnose muß durch immunzytochemische Untersuchungen bestätigt werden. Immunhistologisch werden die Differenzierungsmarker (Intermediärfilamente, speziell Neurofilamente und neuroendokrine Marker) zur Abgrenzung gegen andere Hauttumoren und undifferenzierte Karzinome eingesetzt. Als Primärtherapie wird vorwiegend eine Tumorexzision im Gesunden durchgeführt. Dabei scheint die Kombinationsbehandlung von Tumorexzision und konsekutiver Radiatio auch bei Patienten ohne Befall der regionalen Lymphknoten das Risiko eines Rezidivs oder einer Metastasierung zu senken. Bei Patienten mit ungünstigen prognostischen Indikatoren sollte immer auch eine Strahlenbehandlung durchgeführt werden. Die Ergänzung der chirurgische Primärtherapie (Exzision im Gesunden) durch eine radikale Lymphadenektomie sollte zumindest bei jüngeren Patienten erwogen werden. Eine regelmäßige, engmaschige, langjährige Tumornachsorge ist erforderlich. Treten Fernmetastasen auf, können durch eine Polychemotherapie nur kurzfristige Remissionen erreicht werden. Eine bereits eingetretene Lymphknotenmetastasierung, eine Tumorgröße über 2 cm sowie männliche Geschlechtszugehörigkeit stellen prognostisch ungünstige Indikatoren dar, welche bei der Therapieplanung berücksichtigt werden sollten.
    Notes: Abstract Merkel cell carcinoma is a rare malignant tumor of the skin with predominance in older patients; 78.6% of patients are older than 59 years. Female and male patients are equally involved in the age group below 60 years. After 60 years, Merkel cell carcinomas are more often observed in female patients. The tumor is most often located in the head and neck region (50.8%) or the extremities (33.7%). The average size is 29 mm at presentation. Clinically, only a presumptive diagnosis of Merkel cell carcinoma can be established. The definite diagnosis is made by histological, especially immunohistological methods (detection of intermediate filaments and neuroendocrine markers). The therapy of choice is local excision. Secondary therapy may be a combination of operation and radiation or chemotherapy. Since this combination may reduce the risk of recurrences it should be applied for patients with poor prognostic features. Especially in young patients, additional lymphadenectomy should be discussed. Clinical control is necessary. Distant metastases should be treated by chemotherapy. Bad prognostic features are: lymph node metastasis, size larger than 2 cm, male sex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008068
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  • 5
    Electronic Resource
    Electronic Resource
    Merkel-Zell-Tumor oder neuroendokrines Hautkarzinom (1997)
    Springer
    Langenbeck's archives of surgery 382 (1997), S. 349-358 
    Details
    ISSN: 1435-2451
    Keywords: Merkel cell carcinoma ; Surgery ; Radiotherapy ; Chemotherapy ; Pathology ; Prognosis ; Therapeutic outcome ; Recurrence ; Merkel-Zell-Karzinom ; Chirurgie ; Strahlentherapie ; Chemotherapie ; Pathologie ; Prognose ; Therapieergebnis ; Rezidiv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der Merkel-Zell-Tumor ist ein maligner Hauttumor von neuroendokriner Differenzierung. Er befällt vorwiegend ältere Menschen. 78,6% der Patienten sind älter als 59 Jahre. Bis zum 60. Lebensjahr sind beide Geschlechter gleichermaßen betroffen. Ab dem 60. Lebensjahr überwiegt das weibliche Geschlecht. Der Tumor ist am häufigsten im Kopf-Hals-Bereich (50,8%) und an den Extremitäten (33,7%) lokalisiert und hat zum Zeitpunkt der Diagnosestellung eine durchschnittliche Größe von 29 mm. Bei 30% der Patienten liegen bereits bei der Erstvorstellung klinisch positive regionale Lymphknoten vor. Klinisch ist eine definitive Diagnosestellung nicht möglich. Eine lichtmikroskopisch geäußerte Verdachtsdiagnose muß durch immunzytochemische Untersuchungen bestätigt werden. Immunhistologisch werden die Differenzierungsmarker (Intermediärfilamente, speziell Neurofilamente und neuroendokrine Marker) zur Abgrenzung gegen andere Hauttumoren und undifferenzierte Karzinome eingesetzt. Als Primärtherapie wird vorwiegend eine Tumorexzision im Gesunden durchgeführt. Dabei scheint die Kombinationsbehandlung von Tumorexzision und konsekutiver Radiatio auch bei Patienten ohne Befall der regionalen Lymphknoten das Risiko eines Rezidivs oder einer Metastasierung zu senken. Bei Patienten mit ungünstigen prognostischen Indikatoren sollte immer auch eine Strahlenbehandlung durchgeführt werden. Die Ergänzung der chirurgische Primärtherapie (Exzision im Gesunden) durch eine radikale Lymphadenektomie sollte zumindest bei jüngeren Patienten erwogen werden. Eine regelmäßige, engmaschige, langjährige Tumornachsorge ist erforderlich. Treten Fernmetastasen auf, können durch eine Polychemotherapie nur kurzfristige Remissionen erreicht werden. Eine bereits eingetretene Lymphknotenmetastasierung, eine Tumorgröße über 2 cm sowie männliche Geschlechtszugehörigkeit stellen prognostisch ungünstige Indikatoren dar, welche bei der Therapieplanung berücksichtigt werden sollten.
    Notes: Abstract Merkel cell carcinoma is a rare malignant tumor of the skin with predominance in older patients; 78.6% of patients are older than 59 years. Female and male patients are equally involved in the age group below 60 years. After 60 years, Merkel cell carcinomas are more often observed in female patients. The tumor is most often located in the head and neck region (50.8%) or the extremities (33.7%). The average size is 29 mm at presentation. Clinically, only a presumptive diagnosis of Merkel cell carcinoma can be established. The definite diagnosis is made by histological, especially immunohistological methods (detection of intermediate filaments and neuroendocrine markers). The therapy of choice is local excision. Secondary therapy may be a combination of operation and radiation or chemotherapy. Since this combination may reduce the risk of recurrences it should be applied for patients with poor prognostic features. Especially in young patients, additional lymphadenectomy should be discussed. Clinical control is necessary. Distant metastases should be treated by chemotherapy. Bad prognostic features are: lymph node metastasis, size larger than 2 cm, male sex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02386622
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  • 6
    Electronic Resource
    Electronic Resource
    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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  • 7
    Electronic Resource
    Electronic Resource
    Pyrazolate-Based Oligonuclear Copper and Silver Complexes with N/S Coordination SpheresDedicated to Prof. Dr. Gottfried Huttner on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1441-1447 
    Details
    ISSN: 0009-2940
    Keywords: Pyrazolate complexes ; Bridging ligands ; Copper ; Silver ; N,S-Donor Ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of pyrazole-based potential ligands bearing thioether substituents in 3- and 5-positions of the heterocycle was synthesized [3,5-bis(RSCH2)-pyzH R=Ph (1aH), PhCH2 (1bH), iPr (1cH), tBu (1dH)]. These ligands afford oligonuclear Cu1 and Ag1 coordination compounds [LCu]x (2a-c, L = 1a - c) and [LAg]x (3a-d, L = 1a-d), respectively. The single crystal X-ray analysis of 3c shows the presence of trimeric planar arrays of N,N′-bridging pyrazolates and linear coordinated silver ions, with each two of the trinuclear moieties being linked by two unsupported short intermolecular Ag…Ag contacts [3.041(1) Å]. Molecular-weight determinations for 2a (THF) and 3c (toluene) indicate that hexanuclear entities are preserved in solution. Starting from 1bH the CuII complex [(1b)2Cu2](BF4)2 (4) was synthesized. According to an X-ray crystal structure analysis it consists of dinuclear molecules with two bridging pyrazolates, distorted square planar N2S2 coordination spheres for Cu11 and an axially bridging tetrafluoroborate. Magnetic susceptibility data reveal an antiferromagnetic exchange (J = -206 cm-1) that is among the highest found for doubly pyrazolate bridged dicopper(II) complexes, which is rationalized on the basis of the rather symmetric dinuclear core of 4. The irreversibility of the electrochemical reduction and oxidation processes for the CuII and CuI compounds, respectively, is explained by the inability of the respective coordination framework to adapt to different geometric preferences.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301014
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  • 8
    Electronic Resource
    Electronic Resource
    Dinuclear Cobalt(II) Complexes of Pyrazole Ligands with Chelating Side ArmsDedicated to Prof. Dr. Walter Siebert on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 605-613 
    Details
    ISSN: 0009-2940
    Keywords: Pyrazolate complexes ; Dinuclear complexes ; Bridging ligands ; Cobalt ; Conformational analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of pyrazole-based potential ligands bearing polydentate amine substituents in the 3- and 5-positions of the heterocycle has been synthesized [3,5-bis(R2NCH2)-pyzH R2N = Me2N(CH2)3NMe (2aH), [Me2N(CH2)3]2N (2bH), (Et2NCH2CH2)2N (2cH)]. Upon reaction with two equivalents of CoCl2 they form complexes LCo2Cl3 (3a-c; L = 2a-c, respectively) which are shown crystallographically to contain a dinuclear metal core bridged by both the pyrazolate unit and a chlorine atom, with each cobalt center carrying a further terminal chlorine atom. Two of the ligand side arms in 3b, c are dangling, thus leading to five-coordination of the cobalt(II) centers in all cases. Addition of two equivalents of NaBPh4 to solutions of 3b, c induced coordination of the formerly dangling side arms to the metal centers by substitution of the terminal chlorine atoms. The resulting compounds [LCo2Cl](BPh4)2 (4b, c, respectively) were characterized by X-ray structure analyses. They can be viewed as dinuclear linked versions of tran-type complexes [(tran = tris(aminoalkyl)amine] with distorted trigonal-bipyramidal coordination spheres around cobalt(II). Conformational analyses employing force-field calculations were carried out for 4b, c in order to rationalize the conformations observed in the solid state with regard to the accessible conformational space.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300511
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  • 9
    Electronic Resource
    Electronic Resource
    1,1-Hydroborierung von Alkinen mit 6-Aza-nido-decaboranen (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 947-951 
    Details
    ISSN: 0009-2940
    Keywords: 6-Aza-nido-decaborane ; 9-(1-Alkenyl)-6-phenyl-6-aza-nido-decaborane ; 1,1-Hydroboration of alkynes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,1-Hydroboration of Alkynes with 6-Aza-nido-decaboranes[1]Alkynes AC≡CR′ (R′ = Me, Bu, tBu, SiMe3), that contain a mobile group A, like H or SiMe3, undergo hydroboration by 6-aza-nido-decaboranes RNB9H11 (1a-c, R = H, Ph, PhCH2) and 1,2-migration of the group A, to give the corresponding 9-(1-alkenyl)-6-aza-nido-decaboranes RNB9H10(CH=CR′A) (2a-h). Ethenes AHC=CH2 (A = SiMe3, SnBu3) are hydroborated by 1a, b as well to form products of the type RNB9H10(CH2CH2A) (3a-c). The alkyne Me3SiC=CH undergoes a hydroboration with 1b twice; the formation of (PhNB9H10)2CHCH2SiMe3 (4) proceeds by a 1,1- and a 1,2-hydroboration step, apparently. The crystal structure analysis of (PhCH2)NB9H10[CH=CMe(SiMe3)] (2e; space group Pl) reveals a (Z configuration of the ethene moiety.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280916
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  • 10
    Electronic Resource
    Electronic Resource
    Öffnung des Aza-closo-dodecaboran-Gerüsts durch Basen (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 1225-1229 
    Details
    ISSN: 0009-2940
    Keywords: 1-Organo-1-aza-closo-dodecaborane(12) ; Trialkylamine-1-organo-1-aza-nido-dodecaborane(12) (1/1) ; Undecahydro-1-organo-1-aza-nido-dodecaborate(1-), 2-hydro-, 2-halogeno-, 2-alkoxy-, 2-amino-, 2-alkyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Opening of the Aza-clso-dodecaborane Skeleton by BasesThe aza-closo-borane PhNB11H11 (1a) is opened by the amines NR3 (R = Me, Et) to give the novel aza-nido-dodecaboranes PhNB11H11(NR3) (2a, b). The non-planar open pentagonal face of 2a, b accomodates the N atom, a BHB bridge, and the base-bound B atom, according to NMR spectra and the crystal structure analysis of monoclinic 2b. A similar but more symmetric structure is found when closo-RNB11H11 (1a-c, R = Ph, Me, H) is attacked by anionic bases X- to give nido-RNB11H11X- (3a-j; R/X = Me/H, Me/F, Me/Cl, Ph/OH, H/OMe, Me/OMe, Me/OtBu, Me/NEt2, Me/Me, Me/Bu). The anions are precipitated with cations [K([18]crown-6)], [S(NMe2)3], [N(PPh3)2], [Et2NH2], or [Li(tmeda)2]. The nido-structures of type 2 and 3 are derived from the hypothetical closo-NB12H13.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951281214
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