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  • 1990-1994  (773)
  • 1920-1924
  • 1991  (773)
  • Inorganic Chemistry  (773)
  • 101
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1837-1843 
    ISSN: 0009-2940
    Keywords: β-Hydroxycarboxylic acids, α-alkylation of ; EPC synthesis ; 1,3-Dioxan-4-ones, enolates of ; Enolates, naked ; Schwesinger's base ; Phosphazene P4 base ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enolates A of the dioxanones specified in the title, when generated with lithium amide bases, can only be alkylated with highly reactive electrophiles, and only once. With Schwesinger's t-Bu-P 4 base (a very strong, so-called neutral base, containing 4P and 13N atoms capable of bearing a positive charge in the conjugate P4H+ cation) the dioxanone 1 can be doubly alkylated even with iodobutane (products 16, 17). The 5,6-dimethyl- and 5-benzyl-6-methyldioxanone 2 and 3 can be alkylated diastereoselectively with the formation of quaternary centers at C(5) (products 4, 8 - 14). In one case, the configuration of the product 4 obtained was determined by conversion to a β-lactone 6 and an olefin 7 (a previous assignment had to be revised). Even the 2,5,6,6-tetraalkyl-substituted dioxanone 19 could be further alkylated (→ 20 + 21). Five of the new alkylation products were hydrolyzed to the parent 3-hydroxy-carboxylic acids 5, 22  -  25. The enormous reactivities achieved with the inherently labile enolates and the P411+ counterions are discussed.
    Additional Material: 1 Ill.
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  • 102
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1875-1877 
    ISSN: 0009-2940
    Keywords: Furans ; Oxidation ; Cyclohexenone, 3-(phenylsulfonyl)- ; Butenolide ; Macrolide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Medium and Large Rings, XXIX. - Oxidation of 3,4-Hexamethylenefuran to 2,9-Dioxodecan-10-olide3,4-Hexamethylenefuran (1 a) is oxidized by various methods to give the butenolide 2. Ozonolysis of 2 affords 2,9-dioxodecan-10-olide (3) in 80% yield.
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  • 103
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1879-1880 
    ISSN: 0009-2940
    Keywords: Fluoromethanesulfonyl chloride ; Potassium fluoride ; Crown ether ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Introduction of fluorine into 4-chlorobenzyl chloromethyl sulfide (7) by crown-ether-assisted nucleophilic substitution furnishes 4-chlorobenzyl fluoromethyl sulfide (5), a key intermediate for the preparation of fluoromethanesulfonyl chloride (1).
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  • 104
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1881-1884 
    ISSN: 0009-2940
    Keywords: Dioxastannolane ; Carbon disulfide ; Isothiocyanate ; Cycloaddition, stereospecific ; Lewis base ; 1,3-Dioxolane-2-thione ; 1,3-Dioxolan-2-imine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dioxa-2-stannolanes 1 are readlily activated by Lewis bases such as Bu3P and Et3N to give cycloadducts on reaction with carbon disulfide or phenyl isothiocyanate under mild conditions. In particular, bases play a characteristic role in the reaction with carbon disulfide to produce 1,3-dioxolane-2-thiones 2 in good yields, while spiro compounds 3 (1:2 adducts) are predominantly obtained in the absence of bases.
    Additional Material: 3 Tab.
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  • 105
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1889-1893 
    ISSN: 0009-2940
    Keywords: Clusters ; Rhodium complexes ; Hydroformylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Large Transition Metal Clusters, VIII. - How Do Supported Rh55 Clusters Behave in the Hydroformylation Process?Two-shell rhodium clusters of the type Rh55L12Clx [L = P(tBu)3, x = 20; L = PPh3, x = 6] can be anchored on TiO2 and Na- Y-zeolite. High resolution transmission electron microscopy (HRTEM), BET, and DSC investigations prove that the clusters, about 20 Å in diameter, are fixed on the entrances of the micropores of the supports. The supported clusters catalyze the hydroformylation of ethene and propene variously. During the hydroformylation of ethene without a solvent or in aqueous suspension the catalyst is inactive after a few cycles. However, there is no loss of activity even after 27 experiments if propene is hydroformylated in an aqueous medium.
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  • 106
    ISSN: 0009-2940
    Keywords: Imido ligands ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Imido Complexes - Higher Valent Derivatives of the d-Metal Acids, 1. - New Organometallic Imido Complexes of Molybdenum and Tungsten - Direct Introduction of the Cyclopentadienyl Group by Masking the High-Oxidation StateThe molybdenum(VI)bis(tert-butylimido) complex MO(NtBu)2-Cl2 is converted into the novel organomolybdenum(VI) derivative (η5-C5H5)MO(NtBu)2Cl (1) in excellent yield. The preparation of the pyridine complex W(NtBu)2Cl2py2 (2) provides a convenient starting material for an effective synthesis of the related complex (η5-C5H5)W(NtBu)2Cl (4).
    Additional Material: 1 Tab.
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  • 107
    ISSN: 0009-2940
    Keywords: 1,4-Disila[6]radialenes ; [6] Radialenes ; Chair-twist inversion, kinetic measurements of ; Twist conformers, separation of enantiomers of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polylithiumorganic Compounds, XVI. - 1,4-Disila[6]radialenes: Activation. Parameters of the Chair-Twist Inversion and Analytical Separation of the Enantiomers of the Twist ConformersKinetic measurements of the chair-twist inversion of the 1,4-disila[6]radialenes 2 - 4 have been performed at four different temperatures, respectively. The entropies of activation are found to be negative. While the chair conformers of the radialenes are achiral as expected, the enantiomers of the three twist conformers could be separated by HPLC on an optically active stationary phase.
    Additional Material: 3 Ill.
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  • 108
    ISSN: 0009-2940
    Keywords: Antitumor agents ; Antiviral agents ; Acyclonucleosides ; Pyrimidines ; Acetales ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 2,4-bis-O-trimethylsilyluracil (2) and 5-fluoro-2,4-bis-O-trimethylsilyluracil (3), respectively, with acetals 4a - m of various aliphatic and aromatic aldehydes in the presence of trimethylsilyl trifluoromethanesulfonate (5) at - 30°C gives the 1-(1'-alkoxyalkyl)- and 1-(1'-alkoxy-1'-phenylmethyl)-pyrimidines 6a - m and the corresponding 5-fluorouracil derivatives 7a - f in 40 - 91% yield.
    Additional Material: 1 Tab.
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  • 109
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2041-2046 
    ISSN: 0009-2940
    Keywords: 1,3-Diradicals, energy well, singlet-triplet splitting ; 1,3-Cyclopentanediyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Cyclopentanediyls - Intermediates or Transition States?The energy well of the singlet diradicals 4a and 6 has been determined by the oxygen trapping technique to be 2.7 and 1.9 kcal/mol, respectively. From the oxygen and temperature dependence of the trapping rate of the diradical 4a activation barriers of 2.2 and 4.9 kcal/mol have been derived for the mutual interconversion of the spin isomers with the triplet being the ground state.
    Additional Material: 2 Ill.
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  • 110
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1973-1976 
    ISSN: 0009-2940
    Keywords: 2-Phosphonioallene ligands ; Metallobis(methylene)phosphoranes ; Nickel complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of 2-Phosphonioallene ComplexesThe reaction of the chlorobis(methylene)phosphorane 1 with reactive olefin complexes of nickel and platinium affords the 2-phosphonioallene complexes 4b and 6a,b. The structure of this new class of three-electron donor ligands, involving a lowcoordinated phosphorus (V) cation, has been elucidated by NMR spectroscopy and a single-crystal X-ray study of 6a. The reaction proceeds via a metallobis(methylene)phosphorane intermediate, which could be isolated in the case of the (Et3P)2Pt complex 3a.
    Additional Material: 1 Ill.
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  • 111
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2101-2103 
    ISSN: 0009-2940
    Keywords: Diels-Alder reactions, repetitive ; Band structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of ladder-type oligomers by repetitive Diels-Alder reactions is described. The title compound 1 has been treated with the “bis(dienophile)” 2 at high pressure (7.5 kbar). Under these conditions the formation of oligomers with up to 33 laterally anellated six-membered rings has been achieved. An attempt has been made to analyze the complex stereochemistry of the cycloadditon by using the model compounds 5a, 5b.
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  • 112
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2105-2112 
    ISSN: 0009-2940
    Keywords: Aziridinones, chiral, non-racemic ; α-Lactams ; Butanoic acids, 2-substituted 3,3-dimethyl- and derivatives ; Perbenzoic acid, 3-chloro- ; Oxaziridines ; [2 + 1] Cycloreversion ; Acid catalysis, general ; Ethanol, (R)-1-(9-anthryl)-2,2,2-trifluoro- ; Circular dichroism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereochemistry of Ring Opening of Aziridinones (α-Lactams)The chiral, non-racemic aziridinone (R)-4 (e.e. 92%) reacts with magnesium halides to afford the α-halo amides (S)-3a (e.e. 88.8%), (S)-3b (e.e. 89.0%), and (S)-3c (e.e. 88.2%) in high yields. Acid-catalysed hydrolysis of (R)-4 in aqueous acetone yields 74% of the α-hydroxy amide (S)-3d (e.e. 88.0%). Methanolysis of (R)-4 in [D4]methanol at 60°C followed the first-order rate law with k = 1.53 ṁ 10-5 s-1 yielding quantitatively a 82:18 mixture of the α-methoxy amide (S)-3e (e.e. 89%) and the α-amino ester (R)-14 (e.e. 87%). The latter is obtained exclusively (e.e. 87%) when (R)-4 reacts with sodium methoxide and methanol in ether while only the former is formed (e.e. 88.2%) by slow methanolysis in the presence of a catalytic amount of 4-toluenesulfonic acid. The absolute configurations of the major enantiomers derived from (R)-4 are based on the retention on a Chirasil-L-Val capillary gas chromatography column, CD spectra, and the comparison with authentic samples of (S)-3a, obtained from (S)-tert-leucine [(S)-1] and (S)-3d. The results demonstrate that the N - C(3) bond of the aziridinone (R)-4 is cleaved by nucleophiles with a high degree of stereospecificity and inversion of configuration. This stereochemical course is at variance with that inferred from the methanolysis of the similar aziridinone (R)-7. - Treatment of (R)-4 in [D4]methanol with one equivalent of 3-chloroperbenzoic acid (15) containing 5% of 3-chlorobenzoic acid (16) affords carbon monoxide and the racemic oxaziridine 18 in quantitative yield, which is also obtained from the imine 19 in a very fast reaction. The acid 16 effects slow decomposition of (R,S)-4 into carbon monoxide and imine 19, probably by general acid catalysis. The stereochemical result obtained from (R)-4 as well as the reaction conditions and differences in rate for formation and epoxidation of 19 suggest that in the peracid oxidation of an aziridinone the sequence of events consists of a rate-limiting, acid-catalysed decomposition into carbon monoxide and an imine, followed by very fast epoxidation of the latter. The previous mechanism, invoking as intermediates alleged aziridinone N-oxides, e.g. 17, is not supported by the present study.
    Additional Material: 5 Tab.
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  • 113
    ISSN: 0009-2940
    Keywords: Lanthanoid porphyrins ; Porphyrin double deckers ; Metal bisporphyrinates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes with Tetrapyrrole Ligands, LIX. - Redox Potentials, Near-Infrared Absorption, Ionic Radii, and Ring-Ring Distance in Metal(III) Bis(tetraphenylporphyrinate) Systems with Porphyrin Rings in Different Oxidation StatesAn extended series of tetrabutylammonium salts of bisporphyrinate double decker anions NBu4[MIII(TPP)2] (M = Y, La - Lu except Pm) is described. The complexes are characterized by UV/Vis/NIR and 1H-NMR spectroscopy, cyclic voltammetry, and spectroelectrochemistry. The redox potentials of the new sandwich compounds and the near-infrared absorption energies of their corresponding oxidation products M(TPP)2 and [M(TPP)2]+ are shown to depend linearly on the ionic radii of the central ions. The gradients of the first and second oxidation potentials are positive whereas those of the third and fourth oxidation potentials are negative. This result is interpreted by means of a qualitative molecular orbital diagram describing the ππ interactions of the four frontier orbitals of the two macrocycles in the double decker molecules.
    Additional Material: 5 Ill.
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  • 114
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2197-2201 
    ISSN: 0009-2940
    Keywords: 1,3,2-Diazaborinium Compounds ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3,2-Diazaborinium Compounds  -  New Cationic Boron HeteroarenesThe diazaborinium cation 9 is obtained by the reaction of the vinamidine boron chelate 8 with Et2O - BF3. The cyclic aluminium compound 13 forms with the dichloroboranes RBCl2 (R = Cl, Et, Ph) the cations 15,16a, and 16b. AM1 calculations demonstrate the π interaction of the boron with the nitrogen atoms as well as with the fluoro substituent.
    Additional Material: 1 Ill.
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  • 115
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2075-2084 
    ISSN: 0009-2940
    Keywords: 1,3-Butadienes, polyalkyl ; Allenes ; Rearrangement ; propargylic, SN2′ ; 1,3-Dienes, orthogonal ; Organocuprates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sterically Hindered Double Bond Systems, 2.  -  On the Preparation of Highly Substituted 1,3-DienesHighly alkylated 1,3-dienes may be prepared by treatment of 2-butyne-1,4-diol derivatives with organocuprates in good yield. Thus, the 2,3-dialkylated butadienes 6a - d are obtained by treating the diacetate 4 with two equivalents of the cuprates prepared from the Grignard reagents 5a - d with CuBr/LiBr. Analogously, meso-14 is converted into a mixture of the di-tert-butyl-2,4-hexadienes (Z,E)- and (Z,Z)-15. The procedure may be extended to the synthesis of unsymmetrically substituted 1,3-dienes by either treating the appropriate diacetates with two equivalents of the same cuprate as examplified by the conversion of 18 into 19a and 19b or by employing a stepwise approach in which only one reactive acetate leaving group is available for the cuprate reagent at any given time, thus allowing the change of the organometallic reagent in the course of the synthesis (preparation of the dienes 26 from the monoacetates 22). The mechanisms of these reactions as well as those of several reactions leading to sideproducts are discussed.
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  • 116
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2113-2118 
    ISSN: 0009-2940
    Keywords: Halo(trimethylsilyl)benzenes, carbodesilylation and elimination of ; Carbodesilylation ; Elimination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Halo(trimethylsilyl)benzenes with Electrophiles and Bases - Carbodestlylation and Elimination as Competitive ReactionsElimination to dehydrobenzenes takes place as competitive reaction in the base-catalyzed carbodesilylation of 1-halo-2-(trimethylsilyl)benzenes 1 with carbonyl compounds 2 in the presence of furans 3, 6. Elimination is preferred with increasing leaving tendency of the halides (I 〉 Br 〉 〉 Cl 〉 〉 F) and with decreasing reactivity of the carbonyl compounds. Exclusive elimination to 1,2-didehydrobenzenes - which are trapped with furans - occurs in the reaction when no electrophiles are present.
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  • 117
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2119-2125 
    ISSN: 0009-2940
    Keywords: Didehydropyridines, synthesis of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Didehydropyridines from (Trimethylsilyl)pyridinesHalogen-substituted (trimethylsilyl)pyridines 2, 3, 5 - 7 and trifluoromethylsulfonyloxy-substituted (trimethylsilyl)pyridines 9b, 11b are obtained from 2- and 3-halopyridines 1, 4 or hydroxypyridines 8, 10, and 12. Reactions of the 3- and 2-(trimethylsilyl)pyridines 2,9b and 11b with bases in the presence of furans 15 give only protodesilylation or hydrolysis products but no indication is found for the formation of a 2,3-didehydropyridine. 3-Bromo-4-(trimethylsilyl)pyridine (5a) reacts with KOCMe3 in the presence of furan (15a) to give a mixture of products from which the isoquinoline derivative 20 and the tert-butoxypyridines 23, 24 are formed by addition to 3,4-didehydropyridine. Under comparable conditions far higher yields of 3,4-didehydropyridines are obtained by treatment of the 3-halo-2,4-bis(trimethylsilyl)pyridines 7 with strong bases.
    Additional Material: 1 Tab.
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  • 118
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2145-2146 
    ISSN: 0009-2940
    Keywords: Pyridinium salts ; Ring opening, nucleophilic ; Retro-ene reaction, intramolecular ; 1H-Imidazo[1,2-α]pyrimidines, 2,3-dihydro ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Chloro-4,5-dihydroimidazole (1) reacts with 4-(dimethylamino)pyridine to yield the stable pyridinium salt 2, which on treatment with some C  -  H acids produces 1,2,3,5-tetrahydroimidazo[1,2-α]pyrimidines 6.
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  • 119
    ISSN: 0009-2940
    Keywords: Phosphametallacyclopropanes ; Isolobal building blocks ; Lewis basic behavior ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXXVII. - Synthesis, Structure and Reactivity of Phosphametallacyclopropanes with Isolobal ER (E = N,P,As,Sb) and Fe(CO)4 Building BlocksThe phosphidometallates \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} {[M] = (η5-C5H5)M-(CO)2}, resulting from the metal hydride complexes H[M]PPh2H [M = Cr (1), Mo (2), W (3)] by reduction with nBuLi, react with the geminal dihalides RECl2 to give the three-membered phosphametallacyclopropanes [ER = NC6F5 (M = Cr (1a), Mo (2a), W (3a)), PPh (M = Cr (1b), Mo (2b), W (3b)), PC6H11 (M = Cr (1c), Mo (2c), W (3c)), P-tBu (M = Cr (1d), Mo (2d), W (3d)), P(2,4,6-(tBu)3C6H2) (M = Cr (1e), Mo (2e), W (3e)), As(2,4,6-(tBu)3C6H2) (M = Cr (1f), Mo (2f), W (3f)), Sb-tBu (M = Cr (1g), Mo (2g))]. Reaction of Br2Fe(CO)4 with the corresponding dilithium compounds \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} affords the phosphido-bridged heterodimetallic complexes . According to X-ray structural analyses in 2a and 2f the P - E bond distances are shortened while the Mo - E bonds are significantly elongated compared to a single bond. (OC)5CrTHF is added to the Lewis basic E atom in 2b, 2d, and 2g with loss of THF to give P-tBu (4d), Sb-tBu (4g)]. By this reaction the antimony-containing ring 2g is kinetically stabilized. Because of the low basicity of the N atom in 2a no addition was observed. The ring skeleton of 4b and 4g, undergoes no change by Cr(CO)5 coordination as shown by X-ray structural analyses.
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  • 120
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2191-2195 
    ISSN: 0009-2940
    Keywords: Heterodimetallic complexes ; phosphido-bridged ; Molybdenum complexes ; Rhenium complexes ; Proton exchange, isolobal ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton Exchange in Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 Against Cationic IB Metal Phosphane SpeciesDecacarbonyldirheniumreacts with hexacarbonylbis(η-cyclopentadienyl)dimolybdenum and diphenylphosphane to give Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 (1) with a Mo  -  Re bond as ascertained by an X-ray structure analysis. The bridging H atom of the heteronuclear metal-metal bond in 1 is deprotaned with DBU. The redox condensation reaction of the obtained anion1 and triphenylphosphane IB metal cations gave Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 [M = Au (2), Ag (3), and Cu (4)] containing an MReMo triangle. Their yields increase in the sequence of compounds 4 〈 3 〈 2. 1, 1-, and 2 were characterized by cyclovoltammetric measurements, NMR, IR, and UV/Vis spectra.
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  • 121
    ISSN: 0009-2940
    Keywords: A-Frame complexes ; SO2-bridged complexes ; S, SO, and SO2 ligands ; Insertion reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Sulfur-, Sulfur Monoxide-, and Sulfur Dioxide-Bridged Dimetallic Complexes of the Type [M(CO)(dppm)]2(μ-S)(μ-L) and [(CO)3M'(dppm)2MX](μ-L') (M = Rh, Ir; M' = Mo, W, Mn; L = SO, SO2; L' = S, SO2; X = Cl, CO)The homo- and heterodimetallic complexes [M(CO)(dppm)]2-(μ-S)(μ-SO2) (M = Rh, Ir) (2a, b), [(CO)3M'(dppm)2MCl](μ-SO2) (M' = Mo, W; M = Rh, Ir) (4a - c), and [(CO)3Mn(dppm)2- Rh(CO)] (6) by passing sulfur dioxide through their solutions. The X-ray structure analysis of 5a shows the SO2 ligand in a bridging position, whereas one CO ligand is semibridging. Treatment of the same starting materials with thiirane S-oxide does not lead to the corresponding SO-bridged dimers, with the only exception of 1b, which yields the new SO complex [(Ir(CO)(dppm)]2(μ-S)(μ-SO) (3b). Passing H2S through a solution of 6, the sulfur-bridged complex [(CO)3Mn(dppm)2- Rh(CO)](μ-S) (8) is formed, accompanied by H2 elimination.
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  • 122
    ISSN: 0009-2940
    Keywords: Trinuclear carbonyl complexes ; Molybdenum complexes ; Manganese complexes ; Iron complexes ; Ruthenium complexes ; Osmium complexes ; σ,α-Hydrocarbon bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-bridged Metal Complexes, XXI. - Addition of Tetracarbonylosmate and -ruthenate to Coordinated Unsaturated Hydrocarbons: Trinuclear Complexes with two σ,α-Allyl, Methylallyl, Cyclohexadiene, Cycloheptadiene, Cyclohexadienyl, Cycloheptatrien, and “Thiophene” Bridges The addition of organometallic nucleophiles [M(CO)4]2- (M = Os, Ru) to [(Cp)(ON)(OC)Mo(allyl)]+, [Cp(OC)2Mo(butadiene)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Mn(benzene)]+, [(OC)3Mn(thiophene)]+, [(OC)3-Mo(cycloheptatrienyl)]+ leads to the heterotrimetallic η1:η2-, η1:η3-, η1:η4-, η1:η5-, η1:η6-hydrocarbon-bridged complexes 1 - 7. The structures of cis-(OC)4Os[(μ-η1:η4-C7H9)Fe(CO)3]2 (4), cis-(OC)4Os[(μ-η1:5-C6H6-Mn(CO)3]2 (6), and cis-(OC)4Os-[μ-η1:η6-C7H7-Mo(CO)3]2 (7b) have been determined by X-ray analysis. The fluxional behaviour of 6 in solution has been studied in a temperature range from - 70 to +60°C. The comparison of observed and calculated 1H-NMR data indicates a 1,2-shift mechanism (ΔG+ = 49 kJ/mol).
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  • 123
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2279-2287 
    ISSN: 0009-2940
    Keywords: 1,2-Oxazines, lithiated ; Deprotonation ; Alkylation ; Deuteration ; Regioselectivity ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5,6-Dihydro-5-methylene-4H-1,2-oxazine 1 is smoothly converted by n-butyllithium into 1-Li which reacts with electrophiles such as D2O, carbonyl compounds, dimethyl sulfide, or an azo diester to give the γ-adducts 4a-4f. On the other hand, alkylation of 1-Li occurs exclusively at C-4 of the heterocycle and provides the α-adducts 3g and 3h. These reactions require the activation of 1-Li by tetramethylethylenediamine. Treatment with allyl bromide and methyl acrylate affords mixtures of regioisomers 3 and 4. 1,2-Oxazine 5 with a conjugated C = C bond is less acidic than 1 but is also converted into 1-Li, whilst compound 6, lacking the 6-methoxy group, is not deprotonated under standard conditions. The dianion of 1,2-oxazine 7 is generated by employing an excess of n-butyllithium. This dianion displays a similar regiochemical behavior as 1-Li. Deuterium is exclusively incorporated into the γ-position to give product 8, while methylation occurs at C-4 to produce 9. 1,2-Oxazine 3g with an additional 4-methyl group can also be metalated and affords γ-adducts 10 and 11 upon reaction with D2O or acetone. Treatment with methyl iodide gives a 3:1 mixture of regioisomers 12 and 13. Deuteration of 1,2-oxazines 14 and 16 bearing a 3-CF3 or 3-CO2Et substituent requires more severe deprotonation conditions to provide the γ-adducts 15 and 17 in moderate yields. MNDO calculations of neutral 1,2-oxazines, the corresponding carbanions, and the lithium compounds allow an insight into the structure and charge distribution of these species, and also an estimation of the relative acidities. The regioselectivity of reactions of 1-Li is discussed on the basis of these semiempirical calculations and comparison with related ambident nucleophiles.
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  • 124
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2307-2313 
    ISSN: 0009-2940
    Keywords: Cycloadditions ; Cyclobutenes ; Cyclopropanes ; Tetracyclooctanes ; Photoreactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoreaction of 3,6-Dihydrophthalic Anhydride with AlkynesThe title compound 1 and various alkynes undergo photocycloadditions to give cyclobutenes 3 and/or tetracyclooctane derivatives 4. The proportion varies from 100% cyclobutene (3d) to 100% tetracyclooctane (4e, 1) according to the substituents on the alkyne and the temperature.
    Additional Material: 1 Tab.
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  • 125
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2335-2342 
    ISSN: 0009-2940
    Keywords: Cyclopentenes, 4-methylene-, synthesis of ; Cyclohexenones, 5-methylene-, synthesis of ; Tri(methylene)-methane chromium complexes ; [3 + 2]Cycloadditions with tri(methylene)methane complexes ; Carbene chromium complexes for organic synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 53.  -  4-Methylenecyclopentenes and 5-Methylenecyclohexenones from “Fischer Carbene” Chromium Complexes, Allenes, and AlkynesA method is described for the two-step construction of 4-methylenecyclopentenes 6 and 5-methylenecyclohexenones 7 from Fischer carbene chromium complexes, allenes, and alkynes. In the first step a tri(methylene)methane complex 3 is generated by the addition of the carbene chromium complex (CO)5Cr = C(0Et)Ph (1) to the allene 2. The second step involves an addition of 3 to alkynes HC≡CR [5: R = Ph (a), SiMe3 (b)] at 75°C to give 6 and/or 7 in high chemical yields. The product ratios strongly depend on the substituents R.
    Additional Material: 2 Tab.
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  • 126
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2378-2378 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 127
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2381-2389 
    ISSN: 0009-2940
    Keywords: Platinum complexes ; 1,2-Ethanediamines, 1,2-diaryl- ; Antitumor activity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various erythro- and threo-configurated dichloro[1-(hydroxyphenyl)-2-phenyl-1,2-ethanediamine]platinum(II) complexes were synthesized with the hydroxy group located in either the 2-, 3-, or 4-position of the phenyl ring (38-40). The diastereoisomeric 1-(3-hydroxyphenyl)-2-phenyl-1,2-ethanediamines (31, 32) and threo-1-(2-hydroxyphenyl)-2-phenyl-1,2-ethanediamine (30) were obtained by reduction of the 1,2-diazidoethanes and subsequent ether cleavage. The configuration of the threo-1,2-diazido-1-(2-methoxyphenyl)-2-phenylethane (5) was elucidated by X-ray analysis. The reduction of the erythro-1,2-diaryl-1,2-diazidoethanes, substituted with a methoxy group in ortho or para position, results in elimination reactions with formation of side products. The desired 1,2-diaryl-1,2-ethanediamines were finally synthesized via either an aziridine derivative 21 or by reduction of the respective dioximes 27, 28. The diamine ligands were converted into the corresponding dichloroplatinum(II) complexes 38 - 40.
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  • 128
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2417-2422 
    ISSN: 0009-2940
    Keywords: Organosodium compounds ; Fluorenide carbanions ; Solvatation effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomeric, Tetrameric, and Polymeric Sodium Fluorenide · S [S = Me2N(CH2)2N(Me)(CH2)2NMe2, Me2N(CH2)nNMe2 (n = 2, 3)]The metallation of fluorene with sodium butanide (NanBu) in the presence of N bases yields solvated sodium fluorenide. Base adducts with bi- and tridentate N-chelating ligands have been isolated: Na(fluorenide)(pmdta) (1 [PMDTA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]n (2) [TMEDA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]4) (3) [TMPDA = Me2N(CH2)3NMe2]. According to X-ray diffraction studies monomeric (1), polymeric (2), and cyclic-tetrameric (3) structures are present in the crystal. These pronounced structural variations are explained on the basis of ionic contact aggregates where together with coulomb interactions the steric requirements of the ligands become rather important. Contact distances between Na ions and several C atoms of the carbanion may vary (ca. 260 - 300 pm) and definite coordination numbers become meaningless.
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  • 129
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    Keywords: Aspartame ; L-Aspartyl-L-phenylalanine methyl ester ; Rhodium complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LXIII1).  -  Aspartame as Tridendate Ligand in Organometallic Complexes: Preparation and Structure of Cp*Rh[O2CCH2CH(NH2)C(O)NCH(CH2Ph)CO2Me]Aspartame reacts with [Cp*RhCl2]2 in the presence of base to give the title complex 1 with the deprotonated tridendate dipeptide ester as ligand.
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  • 130
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2453-2456 
    ISSN: 0009-2940
    Keywords: Arsolyl anion ; Heteroaromatics ; Gallium compounds ; Arsoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The permethylated arsolyl anion C4Me4AsLi(TMEDA) (5) has been prepared; its crystal structure (determined by X-ray diffraction) revealed an aromatic heterocycle comparable to the homologous pyrrolyl and phospholyl anions.
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  • 131
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2475-2480 
    ISSN: 0009-2940
    Keywords: Ethylenes, 1,1-diactivate ; Michael acceptors ; 1-Oxa-1,3-butadienes ; Hetero Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title class of 1,1-diactivated ethylenes has been prepared in two steps from aldehydes and t-butyl acrylate by (i) DABCO-catalyzed coupling to give t-butyl 2-(hydroxyalkyl)-2-propenoates 11 and (ii) low-temperature Jones oxidation, followed by swift work up at low temperature. The resulting t-butyl 2-methylene-3-oxoalkanoates 12 are stabilized by sterically demanding and also by aromatic groups R. For primary unhindered alkyl groups, stability is low. The compounds enter into Michael reactions, hetero Diels-Alder additions with enol ethers, and self-dimerization.
    Additional Material: 2 Tab.
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  • 132
    ISSN: 0009-2940
    Keywords: Oxanorbornadiene → oxepine isomerization, limitations ; [6 + 4] Tropone dimerization ; Diene enone [4 + 2] photocycloaddition, intramolecular ; Oxaquadricyclanes, X-ray structure, thermolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Transformations, 761). - Studies in the Area of the Oxanorbornadiene → Oxepine Isomerization. An Intramolecular Diene/Enone [4 + 2] PhotocycloadditionAt room temperature, the “tropone-annulated” oxanorborna diene 2b dimerizes regio- and stereospecifically to give a [6 + 4] adduct (5). Direct photoexcitation of this adduct induces intramolecular diene/enone [4 + 2] addition to 16 followed by a [2 + 2] cycloaddition to provide the dodecacycle 17. An X- ray crystal structure analysis of 17 documents the influence of the heteroatom and of the quasi-bisected ester functions on the length of the three types of oxaquadricyclane - three-membered ring bonds. Direct and sensitized excitation of 2b, c produces polymers; yet, after changing the troponoid chromophor (9, 10) oxaquadricyclane formation takes place (13, 14). In the thermolysis of the annulated oxaquadricyclanes (13, 14) the different cyclopropane C - C bonds are cleaved at a comparable rate.
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  • 133
    ISSN: 0009-2940
    Keywords: 1-Thia-3-azoniabutatriene salts ; 2-Azoniaallene salts ; 1,3-Dipolar cycloadditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Thia-3-azoniabutatriene salts 1 react with alcohols, carbonyl compounds, diazo alkanes, nitrile oxides, nitrones, enamines, and 1,3-butadienes in all cases at the C=S double bond to yield new types of 2-azoniaallene salts (3, 9a, b, 13a, b, 18, 22) and other imines (2, 20). An X-ray diffraction analysis for 9b, the reaction product of 1b with 9-diazofluorene, confirms the proposed constitution.
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  • 134
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2531-2536 
    ISSN: 0009-2940
    Keywords: Aza-crown ethers ; Phthalocyanines, amphiphilic ; Quaternary lutetium bis(phthalocyaninates) ; Quaternerization of acetyl amines ; Lutetium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A straightforward and generalizable synthesis of metal-free and metal (Ni, Pb, Lu) derivatives of symmetrically tetrasubstituted phthalocyanines derived from 15, 16-dibromo- or -dicyano-2, 3, 6, 7, 8, 9, 11, 12-octahydro-5H-benzo[e][1, 4, 7, 13]tetroxaza-cyclopentadecine (1) is described. Quaternarization of the N-acetyl derivatives 7 in a chloroform/dimethyl sulfate mixture gives phthalocyanines 9 soluble in the pH range of 1 - 13. The electronic spectra of the phthalocyanines in buffered solutions (pH 4, 7, and 10) are examined. Furthermore, the electronic spectra of lutetium bis(phthalocyaninate) 9d in water and in DMSO are compared for the first time.
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  • 135
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2569-2575 
    ISSN: 0009-2940
    Keywords: 7-Norcaranylidene carbenoid, substituted ; Cycloallene dimerization ; Tetrakis(arylmethylene)ethane diradical ; 1,2-Bismethylenecyclobutanes ; Bisbenzo[4,5]cyclohepta[1,2-a: 2',1'-c]naphthalene, hexahydro- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloallenes, 7. - A Seven-Membered-Ring Allene Dimer: Preparation from a 7,7-Dibromonorcarane Derivative and ThermolysisPrepared by addition of dibromocarbene to 1,2-dihydro-3-phenylnaphthalene, the 7,7-dibromonorcarane derivative 6 gave the tetra- and pentacyclic hydrocarbons 7 and 8, respectively, on treatment with n-butyllithium. The formation of 8 is considered to proceed via the 1,2-cycloheptadiene derivative 15, which undergoes a dimerisation with the tetramethyleneethane diradical 16 as intermediate. Diradical 16 is also believed to be the intermediate in the thermal rearrangements of 8 to the penta- and hexacyclic hydrocarbons 12 and 13 and of 12 to 13. The structures of 8 and 13 have been determined by X-ray structure analyses. Of special interest is the unusual length (165 pm) of the C-12a - C-12b bond (C-1 - C-22 in Figure 1) in 8.
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  • 136
    ISSN: 0009-2940
    Keywords: Pyridinophane ; Pyridone-pyridol equilibrium ; Selenaphane ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 7,15-Dihydroxy[2.2](2,6)pyridinophane: Synthesis via Organoselenium Compounds and Aggregation by Hydrogen Bonds*7,15-Dihydroxy[2.2](2,6)pyridinophane (5) was prepared by using dimethoxy-diselena[3.3]pyridinophane 3 as a precursor. The X-ray structural analyses of both phanes (5 x 2 HI x 2 DMSO and 3), show the extremely syn-shaped [3.3]phane 3 and the [2.2]phane 5 with antagonistically hydrogen-bonded solvent molecules.
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  • 137
    ISSN: 0009-2940
    Keywords: Zirconium porphyrins ; Hafnium porphyrins ; Porphyrin double deckers ; Metal bisporphyrinates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of new zirconium and hafnium bisporphyrinate double deckers M(P)2 (M=Zr, Hf; P=OEP, TPP)2,3) is described. The complexes are characterized by UV/Vis/NIR and 1H-NMR spectroscopy and cyclic voltammetry. As compared with M=Ce, the redox potentials or the energies of the nearinfrared absorption bands of the corresponding radical cations [M(P)2]+ are lower by ≍ 0.2 V or higher by ≍ 2000 cm-1, respectively, Hence, there is a stronger π-π interaction between the porphyrin ligands as compared with the cerium analogues due to the smaller ionic radii of Zr(IV) and Hf(IV). X-ray crystallography of Zr(TPP)2 confirms the sandwich-like structure of the compound and the close proximity of the porphyrin ligands.
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  • 138
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1083-1087 
    ISSN: 0009-2940
    Keywords: Calcium bis-L-pyroglutamate ; Lithium L-pyroglutamate ; Pyroglutamate coordination and conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calcium bis-L-pyroglutamate and lithium L-pyroglutamate are prepared by reaction of the metal hydroxides with L-pyroglutamic acid in aqueous solution. In the solid state calcium bis-L-pyroglutamate adopts a layer structure, built up by sixteen-membered rings consisting of four L-pyroglutamate ligands bridging four calcium centers by their carboxylate groups. All three oxygen donors of the L-pyroglutamate ligands are attached to metal centers. The calcium atom lies at the center of a slightly distorted octahedron formed by four carboxylate oxygens and two amide oxygen atoms. Lithium L-pyroglutamate also features a layer structure. All three oxygen donors of the L-pyroglutamate ligand have contacts with metal atoms. The coordination sphere of the lithium atom is a slightly distorted tetrahedron consisting of three carboxylate oxygen atoms and one amide oxygen atom. The investigation of aqueous solutions of the compounds by multinuclear NMR (1H, 13C, 17O) indicates extensive electrolytic dissociation in dilute solutions.
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  • 139
    ISSN: 0009-2940
    Keywords: Technetium complexes ; Isocarbonyl ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Carbonyl Syntheses, XX. - Simple Method for the Preparation of Tc(CO)3 Complexes: Synthesis, Structures, and Reactivity of the Novel Cubane-Type Cluster Na[Tc3(CO)9(OCH3)4]Carbonyltechnetium complexes of type LTc(CO)3 are accessible along a simple route from Na[Tc3(CO)9(OCH3)4] (2) which represents a novel alkoxy complex of cubane-type geometry (single-crystal X-ray diffraction study). 2 is an isolable product of the incomplete carbonylation of sodium pertechnetate (1) conducted in methanol. Under carbon monoxide pressure, 2 yields the binary metal carbonyl Tc2(CO)10 (3), pentamethyl-cyclopentadiene gives the halfsandwich complex (η5-C5Me5)Tc(CO)3 (4), and with benzene/hydrochloric acid the ionic complex [(η6-C6H6)Tc(CO)3]Cl (5) is formed.
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  • 140
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2623-2628 
    ISSN: 0009-2940
    Keywords: Aromatization ; Electron transfer ; Isotope effects ; Indirect electrochemical oxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen Transfer Reactions, 171).  -  Electron-Transfer-Induced Aromatization of 1,4-Dihydronaphthalene by Tris(4-bromophenyl)aminiumyl IonsThe first step in the aromatization of 1,4-dihydronaphthalene (1) by the radical cation 2 of tris(4-bromophenyl)amine (3) is a rapid electron transfer in an equilibrium completely shifted to the side of the substrates. The deprotonation of the radical cation 7 of 1,4-dihydronaphthalene is rate-determining as shown by both cyclovoltagrams and isotope effects of deuterated hydrogen donors.
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  • 141
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2651-2653 
    ISSN: 0009-2940
    Keywords: Disulfane, bis[(fluorosilyl)amino] derivative ; Trisulfane, 1,3-bis[(fluorosilyl)amino] derivative ; Selane, bis[(fluorosilyl)amino] derivative ; Helix structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Bis[tert-butyl(di-tert-butylfluorosilyl)amino]trisulfane - a Compound with FSiNSSSNSiF HelixThe lithium derivative of tert-butyl(di-tert-butylfluorosilyl)-amine (1) reacts with sulfur or selenium to give the bis[(fluorosilyl)-amino]di- and -trisulfanes 2, 3 and -selane 4, respectively. The trisulfane 3 crystallizes from n-hexane and exhibits a helical structure (X-ray analysis).
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  • 142
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2663-2666 
    ISSN: 0009-2940
    Keywords: Niobium complexes ; Methylcyclopentadienyl derivatives ; Cyclooctatetraene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Cyclooctatetraene Complexes of Niobium[1]The (butadiene)niobium complexes Cp′Nb(C4H6)2 and Cp′Nb(C4H6)(PMe3)2 (Cp′=C5H4Me) react with cyclooctatetraene (COT) to give Cp′Nb(C4H6)(COT) (2), Cp′Nb(COT)2 (3), and Cp′Nb(PMe3)2(COT) (5) with fluxional COT ligands. The structure of 3 exhibits a prone-η3- and a supine-η4-COT ligand which interchange their role at elevated temperature. That of 5 shows a supine η3-COT ligand.
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  • 143
    ISSN: 0009-2940
    Keywords: Cobalt, (η5-cyclopentadienyl)(1, 3-dibora-4, 5-benzopentafulvene)- ; Iron tricarbonyl complexes ; Triple decker, mixed-metal, slipped ; Calculations, ab initio, EH ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of 1, 3-Dihydro-1, 3, 10, 10-tetramethyl-1, 3-dibora-4, 5-benzopentafulvene with Fe(CO)3 and CpCo Fragments: Synthesis, Crystal and Electronic Structure of Tricarbonyl[(η5-cyclopentadienyl)cobalt][μ,η5:η4-(1, 3-dihydro-1, 3, 10, 10-tetramethyl-1, 3-dibora-4, 5-benzopentafulvene)]ironReaction of the 1, 3-dibora-4, 5-benzopentafulvene 1 with the isolobal organometallic fragments Co(C5H5) and Fe(CO)3 leads to the slipped triple-decker complex 5. It is also formed when 2 is stacked with the Co(C5H5) fragment. The X-ray structure analysis of 5 reveals that the Co(C5H5) fragment is coordinated to the 1, 3-diborole ring, and the Fe(CO)3 group interacts with the Y-shaped B2C=C unit. An MO calculation indicates that the formation of 5 occurs by distortion of 2 (η5- → η4-bonding) and complexation of the Co(C5H5) group. 5 is 16 kcal/mol more stable than its structural isomer 6.
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  • 144
    ISSN: 0009-2940
    Keywords: 2,4-Diaza-1,5-diphosphapentan-3-ones, 2,4-dimethyl- ; Coordination compounds ; Chromium complexes ; Molybdenum complexes ; Tungsten complexes ; Iron complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Compounds with the 2,4-Dimethyl-2,4-diaza-1,5-diphosphapentan-3-one Skeleton; Synthesis, Structure, and Properties of 1,5-Di-tert-butyl-2,4-dimethyl-1,5-diphenyl-2,4-diaza-1,5-diphosphapentan-3-one and Its DerivativesN,N′-Dimethyl-N-N′-bis(trimethylsilyl)urea (1) reacts with tert-butylchlorophenylphosphane (2) to form the monophosphino/ trimethylsilyl-substituted urea 3. Under more vigorous conditions the bisphosphino-substituted derivative 4 was also obtained. The reaction of 4 with the tetracarbonyl norbornadiene derivatives of Cr, Mo, and W furnished the unusual chelate complexes 5-7, in which the ligand 4 is coordinated to the metal through one of the two phosphorus atoms and the oxygen atom of the carbonyl group. The free ligand 4 and the isostructural complexes 5 and 6 were subjected to X-ray structure analyses. The approximate twofold symmetry of 4 is lost as a result of a major conformational change on complex formation. In contrast, 4 reacts with Fe2(CO)9 and with (COD)-PtCl2 (COD=1,5-cyclooctadiene) to give the complexes 8 and 9. In both 8 and 9 the ligand 4 is coordinated by both phosphorus atoms. Reaction of 4 with sulfur and selenium led to the disulfide 10 and diselenide 11, whereas with tellurium no reaction was observed.
    Additional Material: 8 Tab.
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  • 145
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2739-2742 
    ISSN: 0009-2940
    Keywords: Orotate complexes ; Calcium complexes ; Zinc complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From aqueous solutions containing orotate (dianion of 1) and calcium or zinc ions in the molar ratio of 2:1, metal orotate (2-) hydrates are readily obtained in crystalline form at pH 9.0 and 5.4, respectively. According to an X-ray crystal structure analysis, calcium orotate tetrahydrate forms a one-dimensional coordination polymer with each orotate ligand coordinated to no less than three neighboring calcium atoms. In this cation triple, the orotate(2-) anion acts as a carboxylate-O/amide-N-chelating group for the central calcium ion, but also as a carboxylate-O/O-chelating group for the first neighboring calcium ion, and as a terminal amide-O donor for the second. Each calcium ion is thus octacoordinated and linked to three orotate(2-) anions and three water molecules. The fourth water molecule is only engaged in hydrogen bonding. The new zinc orotate(2-) phase features Zn(Or)(H2O)4 units. For the hexacoordinate zinc atom bearing four water molecules the orotate(2-) ligand also acts as an O/N-chelating group. Unlike a discrete Zn(Or)(H2O)4 H2O phase reported earlier, the lattice of the new phase contains further disordered water of crystallization, with the overall composition approaching Zn(Or) 5.5 H2O. The apparent stability of the M(Or) units probably reflects the well-documented carrier function of the orotate ligand for certain divalent metal ions in biological systems.
    Additional Material: 2 Ill.
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  • 146
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1291-1294 
    ISSN: 0009-2940
    Keywords: Dichloroketene, oligomers ; Heterocumulenes ; Tetrachloroallene, dimer ; Octachloro-1,2-bismethylenecyclobutane, X-ray structural analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkynes and Cumulenes, XXIII. - On Some Byproducts of the Dichloroketene Preparation from α,α-Dichloroacetyl ChlorideWhen α,α-dichloroacetyl chloride (1) is dehydrochlorinated with triethylamine in refluxing ether, two oligomers are obtained: 1-dichloroacetoxy-1-dichloromethyl-2,2-dichloroethylene (3) and octachloro-1,2-bis(methylene)cyclobutane (4). The mechanisms of formation of these tri- and tetrameric products of 1 and dichloroketene (2), respectively, are discussed, and an X-ray structural analysis of 4 is reported.
    Additional Material: 2 Ill.
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  • 147
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1301-1310 
    ISSN: 0009-2940
    Keywords: Cyclopentadienyl ligands, fulvene-derived ; Zirconocene complexes ; Hydroboration ; Polymerization catalysts for propene ; Polypropylene, isotactic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of allylcyclopentadienyllithium with 0.5 molar equivalents of MCl4(thf)2 (M=Zr, Hf) furnished the (η5-C5H4CH2CH=CH2MCl2 complexes 3a (Zr) and 3b (Hf), which cleanly added 9-borabicyclo[3.3.1]nonane (9-BBN) to form [η5-C5H4(CH2)3(9-BBN)]2MCl2 (10a, b). Treatment of 3 with butadiene-magnesium led to coupling of one Cp-bonded allyl unit with butadiene to give 5; the remaining CpCH2CH=CH2 group underwent clean H[B(C8H14)] addition when exposed to the 9-BBN hydroboration reagent. (Alkenyl-Cp)2ZrCl2 complexes (9a - d) were prepared starting from fulvenes by deprotonation with the help of LDA and reaction with ZrCl4(thf)2. The complexes [η5-C5H4CH=C(CH3)R]2ZrCl2 9b (R=CH3) and 9c (R=Ph) added 9-BBN to give [η2-C5H4CH(9-BBN)CH(CH3)R]2ZrCl2 12 (R=CH3, rac;-/meso;- ≍ 1:1) and 13 (R=Ph, threo;-/erythro;- ≍ 1:1). The mixtures of diastereoisomers were in each case separated by fractional crystallization. The stereochemical assignments of complexes rac;-12 and meso;-12 were achieved by means of the stereochemistry of polypropylene formed at the 12/methylalumoxane-derived homogeneous Ziegler-type olefin polymerization catalysts. At - 50°C the catalyst from the achiral meso;-12 precursor produced isotactic polypropylene only by means of “chain end control” (σ ≍ 0.7), whereas the use of rac;-12 led to a pronounced participation (≍ 30%) of effective “enantiomorphic site control” (α=0.95) in the CC-coupling reaction.
    Additional Material: 3 Ill.
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  • 148
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2781-2784 
    ISSN: 0009-2940
    Keywords: Bispyrimidotetrazines ; Radicals, persistent ; ESR spectra ; Pyrimidinium salts ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel bispyrimido[1,2-b:1′,2′-e][1,2,4,5]tetrazines 3 are obtained by self-condensation of 1-amino-2-(methylthio)pyrimidinium iodides 1. Zwitterionic bispyrimidines act as intermediates and can be isolated after short heating. Compounds 3 are oxidized with bromine or perchloric acid in acetic acid to give the corresponding radical salts 4. These very stable radicals are characterized by ESR spectra and by cyclic voltammetry.
    Additional Material: 1 Ill.
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  • 149
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2797-2810 
    ISSN: 0009-2940
    Keywords: [2.2]Metacyclophanes ; Chromium complexes ; Chirality (helicity, planar chirality) ; Clathrates ; Configuration, absolute ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Regioselective Complexation of [2.2]Metacyclophanes with TriamminetricarbonylchromiumThe new [2.2]phanes 12, 13, 15, and 17 have been prepared. For the preparation of the known phane 16 a new route has been developed which leads to better yields and includes an interesting reduction with Raney nickel of the naphthalene ring of 15 to a tetrahydronaphthalene ring (→17). The phanes react regioselectively with triamminetricarbonylchromium, which results exclusively in the complexation of the sterically less hindered benzene ring. The bis(tricarbonylchromium) complexes of 18 and 17 were available in good yields, when two equivalents of the precursor of the tricarbonylchromium group were used. 18a was lithiated at -78°C, and the lithiated complexes were trapped with either chlorotrimethylsilane or ethyl chloroformate to yield 4- and 5-substituted products in a ratio of 4:5. Ten X-ray structures, including those of six transition metal π complexes, which were investigated and compared under the aspect of steric interactions between the tricarbonylchromium group and the substituent at the arene ring, are discussed. Interestingly, the tricarbonylchromium group shows no noticable effect on the boat-like deformation of the benzene ring in [2.2]metacyclophanes. A new definition of the “angles of helicity” in helical [2.2]phanes is introduced.
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  • 150
    ISSN: 0009-2940
    Keywords: Phosphatriafulvenes ; Peterson olefination ; Electron densities, inverse ; 1,3-Diphosphacyclobutanes ; Calculations, ab initio SCF ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organophosphorus Compounds, 511). - Phosphatriafulvenes - Phosphaalkenes with Inverse Electron Density2)Peterson olefination of the sterically hindered cyclopropenones 1 with the lithium phosphides 2 yields the so far unknown phophatriafulvenes 3 and 4, which possess inverse electron densities. They are characterized by transition metal complex formation (→7, 8). Acylation of 3a with the carboxylic acid chlorides 11 leads to a great variety of P-acylphosphatriafulvenes 13a-s. They partly dimerize under formation of the 1,3-diphosphacyclobutanes 13 ⇌ 14.
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  • 151
    ISSN: 0009-2940
    Keywords: Disecododecahedradienes ; Pagodanes ; PE spectroscopy ; π-Orbital interaction ; Orbitals, localized, precanonical ; Orbital interaction, through-space ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transannular (orbital) interactions in compounds 1-9 are studied by means of He(Iα)-PE spectroscopy. Unusually strong through-space-dominated π,π interaction is found to be operative in the nonconjugated 1,6-dienes 1, 2, 7, and 8. The π,π splitting of 1.9 eV for disecododecahedradiene 1 is even surpassed by the record value of 2.2 eV for disecodienedione 2, which almost equals that in 1,3-butadiene (2.46 eV). The experimental results are explained by computational methods, especially by analyses of the precanonical MOs.
    Additional Material: 6 Ill.
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  • 152
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 25-29 
    ISSN: 0009-2940
    Keywords: Borole complexes ; {η5-[1-(Diisopropylamino)borole]}metal complexes, internal rotation of, protonation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XVII1). - {η5-[1-(Diisopropylamino)borole]}metal Complexes: Syntheses, Protonation, Internal RotationNew complexes M(CO)4L (M = Cr, W), cis-M(CO)2L2 [M = Mo, W (not isolated)], and (COD)NiL have been prepared from the Diels-Alder dimer L2, where L is 1-(diisopropylamino)borole, C4H4BNiPr2. Complexes of L can be protonated at the nitrogen atom to give stable salts such as [Cr(CO)4(LH)]BF4, [Fe(CO)3(LH)]BF4, [(C6Me6)Ru(LH)]BF4, and [CpCo(LH)]BF4; B  -  N bond dissociation is not observed. Barriers to internal rotation have been determined by variable temperature NMR spectroscopy for Cr(CO)4L, (COD)NiL, and NiL2. Three processes have been identified: rotation of the NiPr2 group around the B  -  N bond, gear-mesh rotation of the isopropyl groups around the C  -  N bonds, and rotation of L with respect to the counter ligands.
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  • 153
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 51-61 
    ISSN: 0009-2940
    Keywords: Selenocarbonyl compounds, perfluorinated ; 1,3-Diselenetanes, perhalogenated ; 2-Selenabicyclo[2.2.1]hept-5-enes ; 1,3-Diselenetan-2-ylium hexafluoroarsenates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of (Perfluoroalkyl)halogeno-1,3-diselenetanes from the Corresponding Selenocarbonyl Fluorides and Reactions with Boron Trichloride or Arsenic Pentafluoride1)Reactions of Hg(SeRt)2 (Rt = C2F5, C3F7, CF3) with (C2H5)2 All or All3 in octamethylcyclotetrasiloxane produce the unstable perfluoroalkaneselenocarbonyl fluorides 1 [R1 = CF3 (1 a), C2F5 (1 b), CF3Se (1 c)]. These compounds are very reactive and polymerize to rubberlike products. On heating the polymers decompose almost quantitatively to the monomers or dimers. In CFCl3 solution 1 dimerizes at 20°C in sunlight to the corresponding cis/trans-1,3-diselenetanes 2. The structure of 2 b is determined by single crystal X-ray diffraction. Different selenocarbonyl derivatives add to unsymmetrically substituted 1,3-diselenetanes 3. 1 a and 1 b react with cyclopentadiene to form the [4 + 2] cycloaddition products 4a and 4c. Halogen exchange reactions take place between 2a  -  d and BCl3. The cis-isomers react much faster than the trans-isomers to give a mixture of cis-, trans-forms of 5. When 2c,d is treated with BCl3 it is possible to isolate and characterize the pure trans-isomer 2d, which is separated by preparative gas chromatography from 5c,d. Fluorine abstraction with formation of 1,3-diselenetan-2-ylium ions (6a  -  f) are accomplished by reactions of 2 or 3 with AsF5 in SO2.
    Additional Material: 1 Ill.
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  • 154
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 87-88 
    ISSN: 0009-2940
    Keywords: Alkylidenesulfur difluoride oxide ; Carbon-sulfur double bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hg[C(COF) = SF2 = O]2 is prepared by the reaction of FCO — CH = SF2 = O with HgF2. This compound represents the third known example of an alkylidenesulfur difluoride oxide. Its molecular structure is the same as that of the most abundant of the three isomers of FCO-CH = SF2 = O. This is assumed to be the result of weak intramolecular Hg… O contacts. With the exception of the fluorine atoms bound to sulfur, all atoms lie approximately in one plane.
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  • 155
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 83-85 
    ISSN: 0009-2940
    Keywords: 1,3,2λ5,4λ5-Dithiadistannetane, 2,4-bis[benzoyl(thiobenzoyl)methanato-O,S]-2,4-dibutyl- ; Anisobidentate ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Butyltin triisopropoxide reacts with benzoyl(thiobenzoyl)methane (LH) to yield BuSn(S)L and an organic sulfide 2 instead of the expected BuSnL3. The use of other butyltin(IV) starting materials invariably leads to the same products. From an X-ray structure determination the tin sulfido complex is found to be a centrosymmetric dimer, [BuSn(S)L]2 (1) with a planar four-membered Sn2S2 ring containing pentacoordinated tin atoms.
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  • 156
    ISSN: 0009-2940
    Keywords: η4-Arene ligand ; Hydrogen bonds, phenol ; Palladium complexes ; Bond activation, P—C ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pd[P(tBu)3]2 reacts photochemically with an excess of phenol in n-hexane to give the dinuclear complex [{P(tBu)2H}2Pd2{μ-P(tBu)2}(μ-η2:η2-C6H5O)] — 3 C6H5OH (1); X-ray crystallography shows a linear chain of three phenol molecules hydrogenbonded to the phenoxide ligand which is η4-coordinated to the Pd2 framework. The π coordination of the phenoxide ring is retained in solution, as evidenced by 1H-NMR spectroscopy.
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  • 157
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 141-147 
    ISSN: 0009-2940
    Keywords: Bond activation, C  -  H, C  -  C ; Transition-metal ions ; Neighbouring group participation ; Tandem mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metastable-ion mass spectra of Fe+ complexes of alkanedinitriles NC(CH2)nCN (n = 1 - 10) exhibit six types of reactions: (1) Loss of the intact ligand to regenerate bare Fe+ as the exclusive (n = 1) or major reaction (n = 2) for the lower homologues; (2) generation of nitriles H(CH2)mCN with m = 0 - 6; (3) formation of unsaturated nitriles CH2 = CH(CH2)mCN with m = 0 - 4; (4) production of C2H4; (5) dehydrogenation, and (6) expulsion of the radicals C2H5 and CH2CN+. The branching ratios of these competing processes are governed by the chain length (CH2)n separating the two CN groups. Mechanistic insight is provided by the study of isotopomers. A comparison of the present data with the previously described behaviour of RCN/Fe+ complexes (R = alkyl) leaves no doubt that for the α,ω-alkanedinitriles it is the Fe+-mediated interaction of the two functional groups which controls the gas-phase chemistry of these organometallic systems. For example, results are presented demonstrating inter alia that losses of H2 and C2H4 proceed by completely different pathways when dinitriles serve as precursors, and either reaction is affected by neighbouring group participation. In distinct contrast, for RCN/Fe+ complexes (R = alkyl) the existing data point to common intermediates.
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  • 158
    ISSN: 0009-2940
    Keywords: Sulfur diimides ; 1,3-Cycloaddition, reductive ; 1,2,4,3-Thiadiazaboretidines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Properties of 1,2,4,3-Thiadiazaboretidines. Crystal Structure of 2,4-Di-tert-butyl-3-phenyl-1,2,4,3-thiadiazaboretidineReaction of sulfur diimides with alkyl(aryl)bis(methylthio)boranes leads to reductive 1,3-cycloaddition of the NSN sequence with formation of the 1,2,4,3-thiadiazaboretidines 2a-g. NMR (1H, 11B, 13C, 15N, 29Si), mass spectra and the results of the X-ray analysis of 21 are reported and discussed. The 11B chemical shifts have been calculated for 3-phenyl-1,2,4,3-thiadiazaboretidine and some related model compounds by the IGLO method and correlate acceptably with the experimental values.
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  • 159
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 203-206 
    ISSN: 0009-2940
    Keywords: Sweetener ; Electrophilic addition ; Cycloalkanecarboxylic acid ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 2 is synthesized in three steps from readily available 2,5-dichloro-2,5-dimethylhexane (8) and vinylidene chloride (9). The key steps are carbocationic additon and cyclization reactions.
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  • 160
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 227-232 
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxiranes ; Ketones, α,β-unsaturated ; (E)-Chalcones ; (E)-2′-Hydroxychalcones ; 2-Cycloen-1-ones ; Caroate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of epoxides 3a - r is achieved in excellent yields by reaction of the α,β-unsaturated ketones 1a-c, 4,4′-disubstituted (E)-chalcones 1d-o, and 2′-hydroxy-4-substituted (E)-chalcones 1p - r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methyl)dioxirane (2b). This method constitutes a useful alternative to the Weitz-Scheffer epoxidation (alkaline H2O2) of such electronpoor substrates.
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  • 161
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 241-245 
    ISSN: 0009-2940
    Keywords: 2-Norbornyl cations, 5,5,6,6-tetramethyl- ; Tetracyclo[4.2.2.12,5.01,6]undec-3-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of 5,5,6,6-Tetraalkyl-2-norbornyl CationsWhen the 6,6-dimethyl-2-norbornyl cation (9) is generated from the tosylhydrazone 5 by way of the diazonium ion 8, a 2H label is distributed equally between positions 1 and 2 of the exo-alcohol 10. The degeneracy of 9, previously derived from solvolytic studies, is thus confirmed for the deaminative route. 5,5,6,6-Tetramethyl-2-norbornanone (25) and tetracyclo[4.2.2.12,5.01,6]undecan-3-one (31) are prepared by using Diels-Alder methodology. The corresponding tosylhydrazones 26 and 32 are employed as precursors for the 5,5,6,6-tetramethyl-2-norbornyl and tetracyclo[4.2.2.12,5.01,6]undec-3-yl cations (11 and 12). Again, the distributions of 2H labels are close to 1 : 1. The angular distortions expected from repulsive interactions of the methyl groups in 11 and from cyclobutane annulation in 12 do not affect the relative energies of the bridged ions.
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  • 162
    ISSN: 0009-2940
    Keywords: Tetrahedranes, organometallic ; 1,3-Diphospha-2-propanone derivatives ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Diphosphenes, XX1). - Synthesis and Properties of the Tetrahedrane [(η5-C5Me5)(CO)2-FeP-PtBu]Fe2(CO)6 and the Metalated 1,3-Diphospha-2-propanones [(η5-C5Me5)(CO)2Fe-PC(O)-PR]Fe2(CO)6 [R = tBu, 2,4,6-(CF3)3C6H2]The reaction of [η5-C5Me5)(CO)2FeP(SiMe3)2 (1) with tBuPCl2 (2a) affords the metalated cyclotetraphosphane [(η5-C5Me5)-(CO)2FeP-PtBu]2 (4a) besides the metal-substituted cyclotriphosphane (η5-C5Me5(CO)2Fe-P[PtBu]2 (5a) and the diphosphane (η5-C5Me5)(CO)2FeP(SiMe3)P(Cl)tBu (3a), which are detected in the reaction mixture by 31P-NMR spectroscopy. Treatment of 4a with excess of Fe2(CO)9 leads to the tetrahedrane [(η5-C5Me5)(CO)2FeP-PtBu]Fe2(CO)6 (6a) and the 1,3-diphospha-2-propanone derivative [(η5-C5Me5)(CO)2FePC(O)-P-tBu]Fe2(CO)6 (7a). Similarily, an analogous complex 7c is obtained from the reaction of in situ prepared (η5-C5Me5)-(CO)2FeP=P-C6H2(CF3)3-(2,4,6) with an excess of Fe2(CO)9.
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  • 163
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 207-212 
    ISSN: 0009-2940
    Keywords: 2,3,6-Trioxypentafulvenes ; Keto-enol tautomerism ; Push-pull system ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of 2,3,6-trioxypentafulvenes with a free position at the ring are described, in which the protection of the C-3 hydroxy group as methoxy or acetoxy derivative has been required. The difference in the behavior of the title compounds in relation to the previously reported 1,4-disubstituted 2,3,6-trihydroxypentafulvenes 2a-e, which only exhibit enol forms, is discussed and attributed to the disappearance of the push-pull system formed by the C-3 enol group and the C-4 electron-withdrawing substituent.
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  • 164
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 233-235 
    ISSN: 0009-2940
    Keywords: Hexaoxacyclotriacontadodecaenes ; Macrocycles ; 2,2-Bis(2-furyl)propane ; 2,5-Bis[1-(2-furyl)-1-methylethyl]furan ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New O6 Macrocycles with 2,2-Bis(2-furyl)propane UnitsThe macrocycles 3a and 6 are prepared in 29 and 16% yield by cyclization of dilithiated 2,2-bis(2-furyl)propane (1) and 2,5-bis[1-(2-furyl) 1-methylethyl]furan (5), respectively, with ethyl N,N-dimethylcarbamate (2).
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  • 165
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 237-240 
    ISSN: 0009-2940
    Keywords: Bicyclo[3.2.1]oct-6-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Conformational effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of 1,4,4- and 2,2,5-Trimethylbicyclo[3.2.1]oct-6-yl Cations1,4,4-Trimethylbicyclo[3.2.1]oct-6-yl cations (18) are generated from the tosylhydrazone 7, by nitrous acid deamination of the amines 6 and 8, and by acetolysis of the brosylates 21 and 24. The product distributions are but slightly affected by the configuration (exo vs. endo) of the leaving groups. The predominant product, 1,4,4-trimethylbicyclo[3.2.1]octan-exo-6-ol (11) is formed without significant redistribution of a 6-2H label. The degenerate Wagner-Meerwein rearrangement of the parent bicyclo[3.2.1]oct-6-yl cation is virtually eliminated by the presence of two methyl groups at C-4. Enhanced conformational strain, raising the barrier to ring flipping, accounts for these observations. Minor products (12, 13) arise from a 7,6-hydride shift of 18, followed by Wagner-Meerwein rearrangement. When the 2,2,5-trimethylbicyclo[3.2.1]oct-6-yl cation (19) is generated directly from the tosylhydrazone 17, the tertiary alcohol 13 is obtained as the major product. The conformational barrier to Wagner-Meerwein rearrangement is compensated by the incipient stabilization of the tertiary carbocation 20.
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  • 166
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 271-274 
    ISSN: 0009-2940
    Keywords: Phosphacumulenes ; Cumulenes ; Calculations, MNDO, SCF ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound phosphabutatriene possesses two energetically closely spaced frontier orbitals, as in methylenephosphane and in phosphaallene. They are built up from the π system or the s̰ orbital of phosphorus by interaction with neighboring π bonds. The extension of these frontier orbitals over all (heavy) atoms makes self-dimerization to different cyclobutane derivatives feasible. Substituent effects on the ordering of s̰ and π are analyzed. Vibrational analyses indicate P=C vibrations of low intensity which decrease with increasing length of the heterocumulene chain. The analysis is extended to the two next higher homologs, which are hitherto experimentally unknown.
    Additional Material: 1 Ill.
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  • 167
    ISSN: 0009-2940
    Keywords: Ketenimines ; Cobalt complexes ; Bond formation, C-C ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloaddition Reactions of Organometallic Complexes, XII1). - Ketenimines from Isocyanides and Diazoalkanes: A New Cobalt-Assisted C-C Bond Forming ReactionThe compounds C5H5Co(CNR)(PMe3) (1-3) react with diaryl-diazomethanes (X)(Y)CN2 to give the C,C-bound ketenimine cobalt complexes C5H5Co[η2-C,C-RN=C=CXY] (PMe3) (4-9), while the reaction of 1-3 with 9-diazofluorene leads to the formation of N,C-bound ketenimine complexes C5H5Co[η2-N,C-RN=C=C(C12H8)](PMe3) (11-13). The different bonding modes of the ketenimine ligands in 4-9 and 11-13, indicated already by the significantly different spectroscopic data, are shown by the X-ray structural analysis of 9-RCoSC (R = CHMePh; X and Y = 4-ClC6H4) and 12 (R = C6H11). On treatment of compounds 4, 6-9, 11, and 13 with an equimolar amount of iodine, free ketenimines are generated. The by-product C5H5Co(PMe3)I2 can be transformed into the starting materials 1-3 in two steps via the cations [C5H5Co(CNR)-(PMe3)I]+ as intermediates.
    Additional Material: 3 Ill.
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  • 168
    ISSN: 0009-2940
    Keywords: Rhenium complexes ; Silylene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of (η5-C5H5)Re(NO)(PPh3)(SiMe2H) (1) and CHCl3, CBr4, and CHI3 give halosilyl complexes (η5-C5H5)Re(NO)-(PPh3)(SiMe2X) [X = Cl (2), Br (3), I (4); 66-84%]. Addition of Me3SiOTf to 2 gives triflate (η5-C5H5)Re(NO)(PPh3)(SiMe2OTf) (5; 97%), which in turn reacts with (Me2N)3S⊕ [SiMe3F2]⊖ to give (η5-C5H5)Re(NO)(PPh3)(SiMe2F) (6; 77%). Reaction of 5 and pyridine gives the base-stabilized silylene complex [(η5-C5H5)Re(NO)(PPh3){SiMe2(NC5H5)}]⊕ TfO⊖ (7; 84%). CH2Cl2 solutions of (η5-C5H5)Re(NO)(PPh3)(CH3) (8) or 2 and Lewis acids are studied by IR and NMR. As assayed by IR, 8/ECl3 solutions (E = B, Al) show ReNO-ECl3 (major) and Re-ECl3 (minor) adducts. Solutions of 2/BCl3 show analogous adducts (-78°C), and in the presence of excess BCl3 (η5-C5H5)Re-(NO-BCl3)(PPh3)(SiMe2Cl) (11) crystallizes. Solutions of 2/AlCl3 show uncomplexed 2 and Re-AlCl3 (major) and ReNO-AlCl3 (minor) adducts. In contrast to 2-7 and 2/BCl3, 1H- and 13C-NMR spectra of 2/AlCl3 suggest an equilibrium with the base-free silylene complex [(η5-C5H5)Re(NO)(PPh3)-( = SiMe2)]⊕ X⊖.
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  • 169
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 417-421 
    ISSN: 0009-2940
    Keywords: Methylenephosphines ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical investigations on a selection of methylenephosphines 1 and related systems are reported. They are shown to possess an irreversible oxidation and reduction wave. An exception is diaminodiphosphene, which reversibly forms a radical anion. A relative ordering of frontier orbitals is possible, based on the redox properties of these systems.
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  • 170
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 371-376 
    ISSN: 0009-2940
    Keywords: Cyclopropane conjugation ; Calculations, ab initio, MNDO ; Vinylcyclopropane ; Ethynylcyclopropane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(I) photoelectron (PE) spectra of 1,1-divinylcyclopropane (1), (Z,E)- and (Z,Z)-1,1-di-1-propenylcyclopropane (2 and 3), 1,1-diethynylcyclopropane (4), 1-ethynyl-1-propynylcyclopropane (5), 1-ethynyl-1-vinylcyclopropane (6), and (Z)-1-(1-propenyl)-1-(propynyl)cyclopropane (7) have been recorded. The interpretation of the first bands of the PE spectra is based on the comparison with related compounds and on the results of MO calculations. For the calculations on 1 - 7 the MNDO method, and in case of 1, 4, and 6 an ab-initio procedure with a 3-21 G basis has been applied. The investigations show that 1, 2, 6, and 7 prefer the bisected conformation while in 3 the propenyl groups are strongly twisted. Our studies reveal also that the three-membered ring shows relais properties and interacts strongly with both π systems.
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  • 171
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 397-402 
    ISSN: 0009-2940
    Keywords: Concave acid ; Macrocycle ; m-Terphenyl ; Benzoic acids ; Acidity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on m-terphenyl units, concave benzoic acids 11a and 12a were prepared via the 2,6-diarylbenzoic acid 7a. Bromination of 7a with NBS gave 9, and cyclization of 9 with dithiols 10 led to the bimacrocyclic concave acids 11a and 12a. Their relative acidities were determined by photometric titrations in ethanol, and the three-dimensional structure of 11a was determined by X-ray analysis.
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  • 172
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 411-413 
    ISSN: 0009-2940
    Keywords: Thiophenophane ; [n]Metacyclophanes ; Reductive ring opening reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and structure of [7]- and [8]metacyclophanes 2, 4 are described. The reductive ring opening of the thiophene rings of [2]metacyclo[2](2,4)- and -(2,5)thiophenophanes 1 and 3 by Raney-Ni affords the corresponding [7]- and [8]metacyclophanes 2 and 4, respectively. Two types of motion have been observed for the methylene chain of [8]metacyclophane 4c, flipping and pseudorotation.
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  • 173
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 515-517 
    ISSN: 0009-2940
    Keywords: Manganese complexes ; Aggregation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influencing the Aggregation of Manganese Complexes by Different Bases: Formation of [Mn(O2CCF3)2(py)4] and [Mn3(O2CCF3)6(benz)6]Manganese powder reacts quantitatively with trifluoroacetic acid to yield Mn(O2CCF3)2 (1). The aggregation of 1 is directed by different N-containing bases. Pyridine (py) forms the mono-nuclear complex [Mn(O2CCF3)2(py)4] (2), while benzonitrile (benz) yields the trinuclear complex [Mn3(O2CCF3)6(benz)6] (3). The X-ray structures of 2 and 3 are described.
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  • 174
    ISSN: 0009-2940
    Keywords: Benzyllithium compounds ; Chirality, central ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal Structure of α-(Trimethylsilyl)benzyllithium·Tetramethylethylendiamin [C6H5CH(SiMe3)Li·TMEDA] und α-(Phenylthio)-benzyllithium·3 Tetrahydrofuran [C6H5CH(SPh)Li - (THF)3] - Two Benzyllithium Compounds with Central ChiralityThe crystal structure analyses of [C6H5CH(SiMe3)Li·TMEDA] (6) and of [C6H5CH(SPh)Li·(THF)3] (7, in which the positions of the benzylic hydrogen atoms have been determined experimentally, reveal compounds with pyramidal benzylic carbon atoms. In 6 lithium is λ2-bound to Cipso and α of the substituted benzylic anion which leads, together with the TMEDA molecule, to a tetra-coordinated lithium atom. In 7 only one Li - C bond is formed, namely that to Cα. Additional coordination with three THF molecules results also in a tetracoordinated lithium atom, The extent of the pyramidalization in 6 and 7 is qualitatively in agreement with quantum-mechanical ab initio calculations [G86, MP2/6-311+ + G(d,p)].
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  • 175
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 587-590 
    ISSN: 0009-2940
    Keywords: [1.1.1]Propellanes, substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis (up to the 10-g scale) and purification of alkyl- and methoxyalkyl-substituted [1.1.1]propellanes are described.
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  • 176
    ISSN: 0009-2940
    Keywords: Azirines ; Oxazoles ; Pyrrolines ; Vinyl azides ; Tetrazoles ; Pyridines, tetrahydro- ; Cyanoacrylates ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Geminal Vinyl Diazides, X. - Methyl 3,3-Diazido-2-cyanoacrylate: Synthesis of Vinyl Azides, 4,5-Dihydro-1H-tetrazol-5-ylidenes, Oxazoles, and N-CyaniminesReaction of methyl 3,3-diazido-2-cyanoacrylate (1) with amines 2 at -30°C yields aminovinyl azides 4. In the presence of equivalent amounts of triethylamine the vinyl azides 4 undergo 1,5′-ring closure to afford the triethylammonium salts 5. Treatment of 5 with hydrochloric acid gives the corresponding 4,5-dihydro-1H-tetrazol-5-ylidene derivatives 6. In contrast thermolysis of 4 leads via azirines 7 to oxazoles 8. Reaction of vinyl diazide 1 with lysine and cystine, respectively, yields bis(vinyl azides) 9. Triethylamine-induced 1,5′-ring closure of 9 produces the bis(triethylammonium) salts 10, which can be transformed under acidic conditions into the corresponding bis(4,5-dihydro-1H-tetrazol-5-ylidene) derivatives 11. With methyl acrylate (17) oxazole 15 reacts via carbonyl ylide 16 in a 1,3-dipolar cycloaddition to give pyrroline 18 (X-ray structure analysis). Thermolysis of the geminal vinyl diazide 1 in the presence of alcohols 19 or primary amines 21 forms the cyanimines 20 and 22, respectively, via methyl 3-aza-2,3-dicyanoacrylate 25. 25 exists as syn/anti isomers which fully agrees with AM1 calculations carried out on cyanimine model systems.
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  • 177
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 655-663 
    ISSN: 0009-2940
    Keywords: 2-Azapentadienyllithium compounds ; Structure in solution ; Calculations, ab initio, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Structures of 2-Azapentadienyllithium Compounds2-Azapentadienyllithium compounds 3 - 10 are easily accessible by deprotonation of N-allylimines 1,2 with lithium diisopropylamide. Their structures in THF solution at various temperatures are studied by means of 1H- and 13C-NMR spectroscopy. 1-Phenyl-substituted 2-aza-pentadienyllithium derivatives adopt all-trans W conformations, whereas 1-alkylsubstituted 2-azapentadienyllithium compounds show s-cis conformations (sickle shapes). 13C shifts of the 2-azapentadienyl carbon atoms are discussed in terms of HOMO coefficients. The experimental structural results are compared with theoretical data obtained by MNDO and ab initio calculations for the corresponding anions. MNDO results are also given for monomeric 2-azapentadienyllithium conformers 13,14.
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  • 178
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    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 179
    ISSN: 0009-2940
    Keywords: cis-Stannyl-boryl-alkenes ; Sulfur diimide anions ; Multinuclear NMR ; 1,2,5-Azastannaboratoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 1,2,5-Azastannaborole Derivatives from Sulfur Diimide Anions and cis-Stannyl-boryl-alkenes - X-ray Crystallographic Study of Two 2,5-Dihydro-1-(imino-λ4-sulfanylidene)-1,2,5-azastannaboratoles(E)-3-(Diethylboryl)-2-(chlorodimethylstannyl)-2-pentene (1) reacts with the sulfur diimide anions 3 [R - NSN-K+, R=tBu (a), Me3Si (b), tBu2P (c)] in a 1:1 ratio, and with 4 (K+;-NSN-K+) in a 2:1 ratio, to give various heterocycles. The first products of the reaction between 1 and 3 [2,5-dihydro-1-(imino-λ4-sulfanylidene)-1,2,5-azastannaboratoles 5a, b, c] are isolated at -30°C and characterized by X-ray crystallography. The compounds 5a,b rearrange into the borole derivates 6a,b (with an additional N—Sn coordination) by transfer of an ethyl group from the boron to the sulfur atom. Ethylene is eliminated from compound 6a (not 6b) to give the diaminosulfane derivative 7a. The 2:1 reaction between 1 and 4 affords an unstable intermediate 8 with a fluxional structure, leading to 9 in which an EtS moiety bridges a borole ring (analogous to 6 but without the additional N - Sn coordination) and a boratole ring (analogous to 5). All compounds are characterized by 1H-, 11B-, 13C-, 15N- (in part), 29Si- and 119Sn-NMR spectra.
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  • 180
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 707-712 
    ISSN: 0009-2940
    Keywords: Osmium mesitylene complexes ; Os - R bonds, formation of ; Osmium aryl hydrido compounds ; Cyclohexene, generation from C6H11MgX ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of [(Mes)Os(CO)Cl2] (3) with PhLi in benzene gives the diphenylosmium compound [(Mes)OsPh2(CO)] (6) whereas with PhMgBr [(Mes)OsPh(CO)Br] (7) is obtained. Treatment of 3 with TolMgBr in benzene or ether affords almost exclusively the monoaryl complex [(Mes)OsTol(CO)Br] (8). Compound 3 reacts with C6H11MgCl to give both [(Mes)Os(C6H11)2(CO)] (9) and [(Mes)Os(C6H10)(CO)] (10) in 60 and 30% yield, respectively. With C6H11MgBr, complex 10 is mainly obtained. Reaction of 7 and 8 with Na/Hg in THF/EtOH gives nearly quantitatively the arylhydridoosmium complexes [(Mes)Os-C6H4R(CO)H] (14, 15). The analogous hydrido methyl compound [(Mes)OsCH3(CO)H] (13) reacts with CCl4 to produce [(Mes)OsCH3(CO)Cl] (17), which is not accessible from 3 and LiCH3 or CH3MgX. The X-ray structure analysis of 10 reveals that the cyclohexene is coordinated in the endo configuration.
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  • 181
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 753-756 
    ISSN: 0009-2940
    Keywords: Metal chelates ; Tetrachloroimidodiphosphates of Al, Ga, In, Sn, Ti ; Metallaheterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Imidodiphosphates of Aluminum, Gallium, Indium, Tin, and Titanium.Me3SiN[P(O)Cl2]2, (1) and Me3SnN[P(O)Cl2]2 (2) are synthesized from NaN[P(O)Cl2]2 and Me3SiCl or Me3SnCl, respectively. Treatment of 1 with AlCl3, GaCl3 InCl3, Me2SnCl2, and TiCl4 yields (3), (4), (5), (6), and (7), respectively. Reaction of LiN[P(O)Ph2]2 with TiCl4 leads to (8). NMR spectra demonstrate that the tetrachloroimidodiphosphate ligand coordinates through the oxygen atoms towards the metal atom.
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  • 182
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 757-759 
    ISSN: 0009-2940
    Keywords: Rhenium(VII) ; Aza compound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Ph3P=NRe(NC6H3iPr2;-2,6)3 - An Aza-Rhenium (VII) Compound.Ph3PNReO3 (1) reacts with three equivalents of 2,6-diisopropylphenyl isocyanate with evolution of CO2 to give the title compound 2. The X-ray single crystal structure of 2 exhibits a rhenium atom tetrahedrally coordinated to four nitrogen atoms (space group P 3).
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  • 183
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 769-771 
    ISSN: 0009-2940
    Keywords: Silaethene ; Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reactivity of Silaethene Me2Si=C(SiMe3)2: Stereospecificity of Diels-Alder Reactions with Hexadienes1,2)[4 + 2] Cycloaddition of trans,trans;- and cis,trans;-2,4-hexadiene to silaethene Me2Si=C(SiMe3)2 (1) takes place stereo-specifically in one step with formation of 3 and 4, respectively. In addition, both reactions lead to ene products 5, 6.
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  • 184
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 773-775 
    ISSN: 0009-2940
    Keywords: Alkyne complexes ; Clusters ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of undecacarbonyl(acetonitrile)triiron (1) with 1,4-dimethoxy-2-butyne (2) yields the alkyne complexes decacarbonyl(μ3;-η2-Verbar-1,4-dimethoxy-2-butyne)triiron (3) and nonacarbonyl(μ3;-η2;-⊥-1,4-dimethoxy-3-butyne)triiron (4). The crystal structure determination of 2 shows that the alkyne ligand is coordinated strictly parallel to one iron-iron edge.
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  • 185
    ISSN: 0009-2940
    Keywords: PE spectroscopy ; Lone-pair interaction ; Orbitals, localized ; Orbitals, precanonical ; 1,5-Diketones, polycyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five polycyclic 1,5-diketones 1 - 4 and 6 are synthesized and studied by means of He(Iα) PE spectroscopy. Comparison of the spectra indicates significant differences in Orbital Interaction Through Bond, which is explained by computational methods, especially by analyses of the precanonical MOs. The lone pair splitting observed in diketone 1, ΔI(n)=0.75 eV, seems to be the largest one ever found in a 1,5-diketone, obviously due to a favourable zigzag topology of the σ frame. In addition, coupling reactions and photoreactivity are studied in compound 6, which seemed to be well suited for Orbital Interaction Through Space. The crystal structure of 6 and its photoproduct 21 is solved by X-ray crystallography.
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  • 186
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 827-832 
    ISSN: 0009-2940
    Keywords: Conformations, solid state ; Conformers in solution ; UV-Vis transition energies and CO/CO dihedral angles ; CO/CO rotational barriers ; Calculations, CNDO/S-CI, MMP1, PIMM / PE spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chromophoric Systems, 2. - Conformation and Absorption of Light in (2-Alkoxyvinyl)ethanedionesThe unusual color properties of yellow 1,2-bis(4,5-dihydrofuran-3-yl)ethane-1,2-dione (1) and colorless 1,2-bis(5,6-dihydro-4H-pyran-3-yl)ethane-1,2-dione (2) in the solid state and in solution are investigated by crystal structure analysis, UV-Vis, PE, and 13C-NMR spectroscopy as well as by reparameterized force-field calculations. Dione 1 takes an antiperiplaner CO/CO conformation of its chromophore in the solid state whereas dione 2 is twisted in this respect by 102°. In solution both chromophores are not planar, but 1 is less distorted (ca. 142°) than dione 2 (ca. 126°). The calculated rotational barrier for CO/CO twisting amounts to 0.9 kcal mol-1 for 1 and to 2.2 kcal mol-1 for 2.
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  • 187
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 867-873 
    ISSN: 0009-2940
    Keywords: Diels-Alder reaction ; Captodative effect ; Calculations, MNDO-PM3 ; Allenic dienophiles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of captodative (c,d) substitution of some olefins and allenes has been investigated by MNDO-PM3 calculations. These results are compared with the Diels-Alder reactions of α-sulfur-substituted allenecarboxylates. α-Sulfonyl allenecarboxylates 6 are a new class of stable gem-diacceptor-substituted allenes.
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  • 188
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 889-896 
    ISSN: 0009-2940
    Keywords: 1-Azapentadienyllithium compounds ; Structure in solution ; Calculations, ab initio, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Structures of 1-Azapentadienyllithium Compounds1-Azapentadienyllithium compounds 2-6 have been prepared by deprotonation of the α,β-unsaturated imines 1 with lithium diisopropylamide. Their structures in THF solution at various temperatures have been studied by 1H- and 13C-NMR spectroscopy. All N-alkyl-substituted derivatives 2 - 5 adopt W conformations of the 1-azapentadienyl unit. The N-tert-butylsubstituted compound 2 shows an (E)-configurated N=C- bond, whereas compounds 3 -5 prefer (Z)-N=C configurations. According to NOE experiments, the triphenyl system 6 has a U-shape structure, probably because of steric interactions of the phenyl substituents. 13C-shifts of the 1-azapentadienyl carbon atoms are discussed in terms of HOMO coefficients. The experimental structural results are compared with theoretical data obtained by MNDO and ab initio calculations for the corresponding anions. MNDO results are also given for monomeric 1-azapentadienyllithium conformers 11.
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  • 189
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 915-922 
    ISSN: 0009-2940
    Keywords: Adamantane ; Adamantanophanes ; Cyclophanes ; Medium-membered rings ; Sulfone pyrolysis ; Phanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Adamantane as a Building Block of New Araliphanes - Synthesis, Spectroscopy, and Crystal StructuresExchange of benzene units for aliphatic building blocks in cyclophanes leads to new molecules of the “araliphane” type. With adamantane the araliphanes 2 - 4 are synthesized. Their stereochemical behavior as shown by NMR studies and X-ray crystallographic analyses differs significantly from that of their aromatic counterparts. The signals of the intraannular adamantane hydrogens are strongly shifted upfield up to δ=- 2.18 (in 2). 4 is obtained as a racemic mixture of enantiomers (in the crystalline state) and shows a boat-like deformation of the benzene moiety.
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  • 190
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 939-945 
    ISSN: 0009-2940
    Keywords: 1-Vinylcyclopropane ; 1-methoxy- ; 1-ethoxy- ; Vinylcyclopropane ; isomerization ; Gas-phase kinetics ; Ring expansion of 1-alkoxy-1-vinylcyclopropanes ; Diradical intermediates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title studies have been carried out with both 1-vinyl-1-cyclopropyl methyl ether (1-OMe) and 1-vinyl-1-cyclopropyl ethyl ether (1-OEt) in the temperature ranges 274.6-324.5 and 273.6 - 323.0°C, respectively. Both reactions predominantly give the vinylcyclopropane-cyclopentene (VCP-CP) rearrangement products 1-cyclopenten-1-yl methyl ether (2-OMe) and 1-cyclopenten-1-yl ethyl ether (2-OEt). Additionally, 2-OEt eliminates ethene (3) in a consecutive reaction at a lower reaction rate compared with the VCP-CP rearrangement. The rearrangements obey first-order kinetics and have been shown to be homogeneous, pressure-independent reactions with the following Arrhenius equations:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {1 - {\rm OMe:}} {{\rm lg}\left({k/s^{-1}} \right) = \left({13.89 \pm 0.23} \right) - \left({191.30 \pm 2.55{\rm kJ mol}^{-1}} \right)/RT\ln 10} \\\end{array} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {1 - {\rm OMt:}} {{\rm lg}\left({k/s^{-1}} \right) = \left({13.77 \pm 0.01} \right) - \left({188.80 \pm 1.85{\rm kJ mol}^{-1}} \right)/RT\ln 10} \\\end{array} $$\end{document}The Arrhenius parameters represent reliable values for general 1-vinyl-1-cyclopropyl alkyl ether→1-cyclopenten-1-yl-alkyl ether (1-OR→2-OR) rearrangements within a large temperature interval in the gas phase. The results support a mechanism proceeding via a diradical. The stabilizing effect of methoxy substitution is discussed.
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  • 191
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    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 192
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 833-839 
    ISSN: 0009-2940
    Keywords: Tetrasulfophthalocyaninato ligand ; Iron complexes ; Isocyanide ligands ; Mößbauer spectroscopy, 57Fe ; Semiconductors, organic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomeric and Bridged Oligomeric (Tetrasulfophthalocyaninato)iron(II) Complexes with Isocyanides and N-Donors as Axial Ligands(Tetrasulfophthalocyaninato)iron(II) (TsPcFe) (1) is treated with the isocyanides tert-butyl isocyanide (tBuNC), 1,4-diisocyanobenzene (dib), 2,3,5,6-tetramethyl-1,4-diisocyanobenzene (me4dib), and 4-isocyano-3,5-dimethylpyridine (me2pyNC), and also with pyrazine (pyz) leading to bisaxially coordinated monomers TsPcFe(L)2 (L=tBuNC, dib, me4dib) and the bridged oligomers [TsPcFe(L)]n (L=dib, me4dib, me2pyNC, and pyz). All these complexes are soluble in methanol or water. The spectroscopic properties of the complexes are described, and the average chain lengths of the bridged oligomers are determined by 1H-NMR spectroscopy. The bridged stacked systems exhibit semiconducting properties with and without iodine doping.
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  • 193
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1035-1039 
    ISSN: 0009-2940
    Keywords: Titanium complex ; Diazadiene ligand ; Envelope structure ; Benzyl compound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diazadiene Complexes of Electron-Deficient Transition Metals: Synthesis, Properties, and Structure of CpTi(diazadiene)ClThe electron-deficient 1,4-diazadiene (DAD) complex CpTi-(DAD)Cl (3), [DAD=1],4-bis(4-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadiene] is prepared either by reduction of CpTiCl3 (1) with magnesium in the presence of free DAD (2) or by the reaction of 1 with Na2DAD. NMR spectroscopic and X-ray diffraction analysis of 3 indicate that the bonding of the DAD ligand has σ2,π-metallacyclopentene rather than η4;-π character. As a result of steric repulsion between the Cp ring and methyl groups of the DAD ligand 3 exhibits a supine (exo) geometry for DAD coordination is solid state. Substitution reaction of 3 affords the novel complex CpTi(DAD)R (R=CH2Ph).
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  • 194
    ISSN: 0009-2940
    Keywords: Ethylene-bridged metal complexes ; Ethanediyl complexes ; Manganese, Rhenium, Ruthenium, Osmium carbonyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Metal complexes, XVIII. - Heterometallic Ethylene-Bridged Complexes (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5 and (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5Addition of [(OC)5Re(C2H4)]+ to the carbonylmetallates [Mn(CO)5]-, [RuCp(CO)2]-, [Os(CO)4]2-, [Os3(CO)12]2- affords the title complexes in a directed way. The dynamic behaviour of (OC)5ReCH2CH2Mn(CO)5 in solution is attributed to a dyotropic exchange of the pentacarbonylmetal groups on the CH2CH2 bridge.
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  • 195
    ISSN: 0009-2940
    Keywords: Palladium complexes ; Platinum complexes ; Rhodium complexes ; Iridium complexes ; Glycine, C-allyl-, C-vinyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LVIII. - C-Allylglycine and C-Vinylglycine Complexes of Palladium(II), Platinum(II), Rhodium(III), Iridium(III) and Reactions with NucleophilesThe synthesis of the complexes (R13P)(Cl2Pt(C-allylglycine ester) (1), (2) and of (η5-C5Me5)Ir(C-allylglycinate) (6) with tridentate O,N,η2;-C—C allylglycinate as ligand is described. Addition of enolates (Nu-) to the coordinated C=C bond of 2 gives the γ-C-metallated α-amino acid ester complexes (3). In most cases the platination occurs stereoselectively to yield the five-membered metallacycle with the substitutents CH2Nu and CO2R2 in trans position. From 3d the new α-amino acid H2NCH(CO2Me)-(CH2)3C(Ph)(CO2Et)21 (4) is cleaved. The structures of 3c and 6 have been determined by X-ray diffraction. C-Vinylglycinate can be stabilized at the metal atom in the complexes (10) (M=Rh, Ir).
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  • 196
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 967-969 
    ISSN: 0009-2940
    Keywords: Paternó-Büchi reaction ; Photochemistry ; Chiral induction ; Acyl cyanides ; achiral and chiral ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The acyl cyanides 1a - d are prepared from the corresponding acyl chlorides. The Paternó-Büchi reaction of 1a  -  f with furan (2) yields the bicyclic oxetanes 3a - f with an endo/exo ratio varying from 3.5: 1 (1a) to 16: 1 (1d). However, in the reaction of the chiral acyl cyanides 1b and 1c, a low chiral induction is observed (maximum de: 13%).
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  • 197
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 975-980 
    ISSN: 0009-2940
    Keywords: Niobium complexes ; Cyclopentadienyl derivatives ; Butadiene derivatives ; Acetylene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Butadiene)(cyclopentadienyl)niobium ComplexesThe known bis(butadiene)(cyclopentadienyl)niobium complex (C5H4R)Nb(C4H6)2 (1, R=H) exists in solution as a 1 : 1 mixture of a bis(cis-butadiene) isomer 1a and a (cis-butadiene)(trans-butadiene) isomer 1b. In solution the barrier to isomerisation is 80 ± 2 kJ/mol. New derivatives 2 (R=Me) and 3 (R=SiMe3) of 1 are described. One of the butadiene ligands in 1 - 3 is readily substituted with CO, CNtBu, P(OMe)3, and PMe3. CpNb(PMe3)2(C4H6) (7) reacts with disubstituted acetylenes to form acetylene complexes CpNb(PMe3)(C4H6)(RC=CR') (8: R, R'=Ph, 9: R=Me, R'=Ph, and 10: R=Ph, R'=SiMe3), The structure of 9 resembles that of bent metallocene derivatives with the acetylene acting as a 2-e ligand.
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  • 198
    ISSN: 0009-2940
    Keywords: Metallacyclic organoaluminium, -gallium and -indium compounds ; MOVPE precursors ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecularly base-stabilized four-coordinated metallacyclic organoaluminium, -gallium, and -indium compounds C5H10-Al(CH2)3NMe2 (4), C4H8Ga(CH2)3NMe2 (5), C5H10Ga(CH2)3N-Me2 (6), C5H10GaCH2CH(Me)CH2NMe2 (7), C4H8Ga(CH2)4NMe2 (8), C5H10Ga(CH2)4NMe2 (9), EtAl[(CH2)3]2NMe (10), MeGa-[(CH2)3]2NMe (11), EtGa[(CH2)3]2NMe (12), MeIn[(CH2)3]2NMe (13), and (14) have been synthesized by the reaction of [3-(dimethylamino)propyl]aluminium dichloride (1), [3-(dimethylamino)propyl]gallium dichloride (2), [3-(dimethylamino)-2-methylpropyl]gallium dichloride (3), or [4-(dimethylamino)butyl)gallium dichloride with the respective bis-Grignard reagents or by the reaction of the organometal dichlorides RMCl2 with bis[3-(chloromagnesio)propyl]methylamine or with N,N′-bis[3-(chloromagnesio)propyl]-N,N′-dimethyl ethylenediamine. Aluminium or gallium trichloride reacts with tris[3-(chloromagnesio)propyl]amine to give Al[(CH2)3]3N (15) and Ga[(CH2)3]3N (16). The 1H-, 13C-NMR and mass spectra of the new compounds as well as the X-ray crystal structure of 16 are discussed. 4, 6, and 12 have been tested successfully as MOVPE precursors.
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  • 199
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1143-1148 
    ISSN: 0009-2940
    Keywords: Ironcarbonyl complexes ; ortho-Metallation ; o-Semidine rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iron Carbonyl Induced o-Semidine Rearrangement of 1-Alkyl-2-aryldiazenesIrradiation of pentacarbonyl iron in the presence of Me3C - N=N - Ar (Ar=phenyl, p-tolyl, p-CH3OC6H4) produces in the first step ortho-metallated complexes of the type Me3C - N - N(H)RC6H3Fe(CO)3Fe(CO)3 (2a-c, R=H, Me, MeO). In a thermal consecutive step these intermediates undergo an o-semidine rearrangement to Me3C - NFe(CO)3 - Fe(CO)3N(H)RC6H3 (1a-c). The structure of 1a has been elucidated by X-ray structure analysis. Dynamic 13C-NMR spectra indicate restricted rotation of the Me3C group and hindered carbonyl scrambling for the latter and former complexes, respectively.
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  • 200
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    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1161-1162 
    ISSN: 0009-2940
    Keywords: Semiconductor ; Photocatalysis ; Carbon dioxide ; Formate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon dioxide is catalytically reduced to formate in a suspension of zinc sulfide in water/2,5-dihydrofuran when irradiated (λ ≥ 290 nm). Turnover rates are in the range of 1.5 monolayers CO2/h. No reaction occurs at pH=12, and a very slow one at pH=3.2,5-Dihydrofuran functions as reducing agent which is oxidized to dehydro dimers. When it is substituted by 2-propanol, no CO2 reduction is observed. Semiconductor photocatalysis by a two-electron transfer from zinc sulfide to adsorbed hydrogen carbonate is assumed as the key step of CO2 fixation.
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