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  • 101
    Electronic Resource
    Electronic Resource
    Highly Functionalized Vinylcyclopropane Derivatives by Regioselective and Stereoselective Reactions of Fischer Carbene Complexes with 1,4-Disubstituted Electron-Deficient 1,3-DienesDedicated to Professor Klaus Hafner on the occasion of his 65th birthday. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2723-2729 
    Details
    ISSN: 0009-2940
    Keywords: Chromium complexes ; Carbene complexes ; 1,3-Dienes, electron-deficient ; [2 + 1] Cycloaddition ; Vinylcyclopropanes, donor-acceptor-substituted ; 1,1′-Bicyclopropane-2-carboxamides ; Regioselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal reaction of Fischer carbene complex 1 with electron-deficient 1,3-dienes such as methyl (E,E)-2,4-hexadienoate (2) provided functionalized vinylcyclopropanes like 3 in good yields. Similar results were obtained by employing related unsaturated esters 4, 17, and 21 or nitrile 6. The periselectivity as well as regioselectivity of these carbene-transfer reactions are generally very high, and the diastereomer with the methoxy group cis-positioned with respect to the olefinic moiety is largely favoured (〉85:15). A mechanistic rationale of these observations is given. Double adducts were only formed as minor sideproducts in these reactions, but by employing amide 13 as electron-deficient diene they were very easily formed with 1. The [2 + 1] cycloaddition could also be extended to methylcarbene complex 24 and diene 2, but the corresponding vinylcyclopropane 25a was so far only obtained in low yield.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251218
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  • 102
    Electronic Resource
    Electronic Resource
    Thermolyse von 1,2,3,4,6,7,8-Heptaazaspiro[4.4]nona-2,7-dienen, [3 + 2]-Cycloaddukten von Aziden an 5-Alkyliden-4,5-dihydro-1H-tetrazole (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2749-2756 
    Details
    ISSN: 0009-2940
    Keywords: Cycloaddition, 1,3-dipolar ; [3 + 2] Cycloaddition and [3 + 2] cycloreversion, equilibrium by ; [2 + 1] Cycloreversion ; Thermolysis ; Spiro[4.4]nona-2,7-dienes, 1,2,3,4,6,7,8-heptaaza- ; 1H-Tetrazoles, 5-alkylidene-4,5-dihydro- ; 1H-1,2,3-Triazoles, 4,5-dihydro-5-imino- ; Aziridines, imino- ; 1,2,3,4-Tetrazines, 5-imino-1,4,5,6-tetrahydro- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermolysis of 1,2,3,4,6,7,8-Heptaazaspiro[4.4]nona-2,7-dienes, [3 + 2] Cycloadducts of Azides and 5-Alkylidene-4,5-dihydro-1H-tetrazolesOn thermolysis of the title compounds at 20-150°C, three modes of ring cleavage are observed, viz. [3 + 2] cycloreversion of the triazole (path A) or the tetrazole ring (path B) to azide 2 and the corresponding dipolarophile, or extrusion of molecular nitrogen from the triazole ring with concomitant 1,2 shift of a nitrogen atom of afford an iminotetrahydrotetrazine 31 (path C). An equilibrium between [3 + 2] cycloaddition and cycloreversion (path A) is established starting from the heptaazaspiro[4.4]nonadienes 4. Irreversible [3 + 2] cycloreversion of the tetrazole ring (path B) is observed on thermolysis of 6, yielding azide 2 and iminodihydrotriazoles 7. Path A and B compete in the thermolysis of 6e affording, besides methyl azide (2a), 5c and 7e. Because path A is reversible, the former disappears again while the latter extrudes molecular nitrogen to yield the iminoaziridines (E)- and (Z)-12 which decompose to the imine 13 and methyl isocyanide (14). Competition between path A and B is also observed on thermolysis of 15 and, probably, the diphenyl compound 21 as well. The latter affords a complex mixture comprising the iminodihydrotriazole 16, the iminoaziridines 18 and 23, the [2 + 1] cycloreversion products 14 and 19 of 18, and the 2-aminoindole 26 which is formed by isomerization of 18 and/or 23. None of the [3 + 2] cycloreversion reactions, but only extrusion of molecular nitrogen and formation of 31 (path C) are observed on thermolysis of the nitrophenyl spirocycles 29. The course of the thermolyses is mainly governed by the size and the electronic character of the substituent that stems from the azide used in the formation of the title compounds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251221
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  • 103
    Electronic Resource
    Electronic Resource
    Kristallstruktur und Gasphasenuntersuchungen von lithiiertem Acetessigsäure-tert-butylesterHerrn Professor Günther Maier zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2779-2782 
    Details
    ISSN: 0009-2940
    Keywords: Lithium enolate ; PE spectroscopy ; Mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal Structure and Gas-Phase Investigations of Lithiated tert-Butyl AcetoacetateThe lithium enolate 2, generated either by deprotonation of tert-butyl acetoacetate (1) or by pyrolysis of lithiated tert-butyl acetate (3) is crystallized from toluene. The X-ray diffraction analysis of unsolvatized 2 reveals a hexameric structure. Thereby, the central skeleton is formed by two Li-O six-membered rings, and the carbonyl group of the ester moiety serves to complete the fourfold coordination of the lithium atom. The thermal stability of 2 enables the very first mass spectrometric and photoelectron spectroscopic investigation of a lithium enolate. The lithium compound 2 forms aggregates even in the gas phase. The first vertical ionization energy of 2 is found to be significantly lower than those observed in the photoelectron spectra of both the enol ether 5 and the ester 1.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251225
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  • 104
    Electronic Resource
    Electronic Resource
    Ergiebige Herstellung von (R)- und (S)-3,3,3-Trifluormilchsäure und von (R)- und (S)-(Trifluormethyl)oxiran (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2795-2802 
    Details
    ISSN: 0009-2940
    Keywords: Resolution by crystallization of diastereoisomeric salts ; Perfluoropropylene oxide ; Trifluoropyruvate ; Capillary GC determination of ratios of enantiomers ; Cyclodextrine-derived GC columns ; Determination of the sense of chirality by chemical correlation ; pKs of 3,3,3-trifluoro-2-hydroxypropanoic and 4,4,4-trifluoro-3-hydroxybutanoic acid ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simple Access to (R)- and (S)-3,3,3-Trifluorolactic Acid and to (R)- and (S)-(Trifluoromethyl)oxiraneEthyl trifluoropyruvate (from hexafluoropropylene oxide) is reduced by NaBH4 to rac-trifluorolactic acid which is resolved on a 100-g scale by salt formation with (R,R)- and (S,S)-2-amino-1-phenyl-1,3-propanediol (readily available intermediates of industrial chloroamphenicol synthesis). The enantiomerically pure trifluorolactic acids (〉99% ee by GC analysis on cyclodextrin columns) are converted into (R)- and (S)-(trifluoromethyl)oxirane in an overall yield of 73% by the following steps: esterification, THP protection of the OH group, LAH reduction and mesylation to the 2-THP-protected mesylate of 3,3,3-trifluoro-1,2-propanediol, and one-pot deprotection (Dowex 50) and cyclization (NaOCH2CH2OH) in ethylene glycol. The enantiomeric purity of the oxirane (b.p. 39=C, isolated on a 10-g scale) was determined by GC to be 〉99%. Possible synthetic targets are mentioned which should be accessible in enantiomerically pure form from the (trifluoromethyl)oxirane described here.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251227
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  • 105
    Electronic Resource
    Electronic Resource
    Synthesis of Homobenzoctamine [9,10-Dihydro-9-(1-methylaminomethyl)-9,10-propanoanthracene] and Homomaprotiline [9,10-Dihydro-9-(3-methylaminopropyl)-9,10-propanoanthracene] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2809-2812 
    Details
    ISSN: 0009-2940
    Keywords: Benzoctamine, homologue ; Maprotiline, homologue ; Antidepressants ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of homobenzoctamine (10) and homomaprotiline (19) is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251229
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  • 106
    Electronic Resource
    Electronic Resource
    Cobaltkomplexe mit As4-Liganden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2367-2372 
    Details
    ISSN: 0009-2940
    Keywords: Tetraarsenic ligands ; Oxidative addition ; Bond cleavage in As4, successive ; Cobalt As4 complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cobalt Complexes with As4 LigandsThe reaction of [Cp*Co(μ-CO)]2(Co = Co) (1) with As4 in boiling toluene gives the cobalt complexes [Cp*Co(CO)(η1:1-As4)] (2), [{Cp*Co(CO)}2(μ-η1:1:1:1-As4)] (3), exo,endo-[Cp*Co(μ-η4:1:1-As4)Co(CO)Cp*] (4a, b), and [Cp*Co(μ-η2:2-As2)]2 (5), Cp* = C5Me5. 2,3, and 4b have been characterized by X-ray structure analyses. With respect to the mechanism of this reaction the successive cleavage of two, three, and four As-As bonds of yellow arsenic, As4, has been proved.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251107
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  • 107
    Electronic Resource
    Electronic Resource
    Organische Synthesen mit Übergangsmetall-Komplexen, 62. Erste Carbenkomplexe (M=Cr, W) mit Kohlenhydrat-Substituenten (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2773-2778 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes of carbohydrate derivatives ; Vinylcarbene chromium and tungsten complexes ; α-D-Mannofuranosides, 2,3:5,6-di-O-isopropylidene-, of carbene complexes ; α-D-Allofuranosides, 1,2:5,6-di-O-isopropylidene-, of carbene complexes ; α-D-Glucofuranosides, 1,2:5,6-di-O-isopropylidene-, of carbene complexes ; 1,2-Propadienyliden tungsten complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 62. - First Carbene Complexes (M=Cr, W) with Carbohydrate SubstituentsThe first examples of transition metal carbene complexes of carbohydrate derivatives are described: 1,2:5,6-Di-O-isopropyliden-α-D-glucofuranose (2a), 1,2:5,6-di-O-isopropylidene-α-D-allofuranose (2b), and 2,3:5,6-di-O-isopropyliden-α-D-mannofuranose (2c) add regiospecifically at C-3 of alkynylcarbene complexes LnM=C(OEt)-C≡CPh 1 [LnM=Cr(CO)5 (a), W(CO)5 (b)] to give vinylcarbene complexes LnM=C(OEt)-CH=C(Ph)-O(sugar) (E/Z)-3a-g in good to excellent yields. As a minor side reaction the alkynyl carbene complex (CO)5W=C(OEt)-C≡CPh (1b) isomerises to give the 1,2-propadienylidene complex (CO)5W=C=C=C(OEt)C6H5 (4b).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251224
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  • 108
    Electronic Resource
    Electronic Resource
    On the Reactions of Fe(CH2)+ with 1,7-Octadiene in the Gas Phase (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2817-2819 
    Details
    ISSN: 0009-2940
    Keywords: Transition-metal ions ; Metathesis, gas-phase ; Bond activation, CH and CC ; Ion cyclotron resonance mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast to the reactions of “bare” Fe+ with 1,7-octadiene (1), the chemistry of Fe(CH2)+ with 1 represents a “textbook” example for a gas-phase metathesis process to generate in a clean fashion Fe(C2H4)+. Similarly, for the formation of Fe(C6H6)+ a mechanism is suggested which is in keeping with the experimental findings. In contrast, the reactions of Fe(CH2)+ with 1 leading to Fe(C3H4)+ and Fe(C4H6)+ are so complex that a coherent description is not yet possible.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251231
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  • 109
    Electronic Resource
    Electronic Resource
    Substituenteneinflüsse auf die Struktur von 1-Azaspiropent-1-en (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2513-2515 
    Details
    ISSN: 0009-2940
    Keywords: 1-Azaspiropent-1-ene, 2-phenyl, and dimer, molecular structures of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituent Effects on the Structure of 1-Azaspiropent-1-eneLow-temperature (199 K) X-ray structure analyses of the azaspiropentene 1 and its dimer 2 have been undertaken. The peripheral bonds of 1 (C-C 1.544, C=N 1.278 Å) are elongated because of steric strain and conjugation with the phenyl ring (for C=N). The distal bond (C-C 1.485 Å) in the three-membered ring of 2 is shortened by the substituent effects of the N=C and C=N groups.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251125
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  • 110
    Electronic Resource
    Electronic Resource
    Vielgliedrige Donor-substituierte Kohlenwasserstoffringe (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2523-2531 
    Details
    ISSN: 0009-2940
    Keywords: Carbocycles ; Large rings ; Macrocycles ; [2n]Metacyclophanes ; Müller-Röscheisen reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many-Membered and Donor-Substituted Hydrocarbon RingsThe preparation of large rings 2 of the [2n]metacyclophane type by the Müller-Röscheisen method is described. Yields of cyclic products, potential ligand or host character and ring size can be controlled by intra- and extraannular OCH3 groups. The 40-membered macrocyclus 24 containing eight substituted benzene rings is the largest ring compound of this series isolated so far in pure form. Large substituents OR in position 2 of the starting bis(bromomethyl) compounds lead to higher ring member numbers. The new macrocyclic compounds, with the exception of the “dimer” 7, are all conformationally flexible according to 1H-NMR spectra. X-ray structural analyses were performed of the macrocycles 10, 13, 17, and 18; the inclusion of solvent molecules is proven.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251127
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  • 111
    Electronic Resource
    Electronic Resource
    Pressure-Induced Diastereoselectivity in Photochemical [2 + 2] Cycloaddition Reactions (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2577-2582 
    Details
    ISSN: 0009-2940
    Keywords: High-pressure reactions ; [2 + 2] Photocycloaddition reactions ; Diastereoselectivity ; Cyclopentenones ; Cyclopentenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical [2 + 2] cycloaddition reactions under high pressure of cyclopentenone 1a or cyclohexenone 15, as well as of 1a or 3-substituted cyclopentenones 1b-d with cyclopentene (2), and of 1b with 3,3-dimethyl-1-butene (18) are described. Whereas the pressure dependence on the regioselectivity in the photoaddition of 1a and 15 is very small, δδV≠ values up to 2.0 ± 0.3 cm3 · mol-1 have been found for the diastereoselectivity in the reactions of 1a-d with 2 and of 1b with 18.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251132
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  • 112
    Electronic Resource
    Electronic Resource
    Preparation and Structure of Hexakis[(trialkylphosphane)aurio(I)]methanium(2+) Salts [(LAu)6C]2+(X-)2 with L=Et3P, iPr3P and X=BF4-, B3O3F4- (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2705-2710 
    Details
    ISSN: 0009-2940
    Keywords: Auriophilicity ; Gold(I), phosphane complexes ; Methanium, hexaaurio(I) compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hexaaurated carbon complexes of the type [(R3PAu)6C](BF4)2, R=Et (2a), iPr (2b) have been prepared by the reaction of the appropriate (phosphane)gold(I) chlorides R3PAuCl (1a and 1b) with tetrakis(dimethoxyboryl)methane, 13C-enriched at the central carbon atom, in the presence of excess of CsF in HMPT at room temperature. The products 2a and 2b are characterized by standard spectroscopic methods including direct detection of the interstitial C atoms by 13C-NMR spectroscopy. The crystal structure of the compound [(iPr3PAu)6C](B3O3F4)2 · 3 CH2Cl2 (3), obtained from partial (anion) hydrolysis has been determined. It contains dications with a central carbon atom surrounded by six (phosphane)gold(I) units. The edges of the CAu6 octahedron represent short Au-Au contacts (aprox. 3.0 Å), which strongly contribute to the formation and stability of these hypercoordinated species. Attempts to prepare a corresponding hexaauriomethanium dication starting from tBu3PAuCl (1c) failed owing to the bulkiness of the (tri-tert-butylphosphane)gold(I) unit. The X-ray structure analysis for 1c verifies an extremely crowded environment of the gold atom with small Au - P - C angles of only 107° leading to efficient shielding of the metal atom by methyl groups.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251214
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  • 113
    Electronic Resource
    Electronic Resource
    Dimethyldioxirane Oxidation of Enamines: First Spectral Evidence for Enamine Oxides by Stabilization through N-Silylation (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2719-2721 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Enamines, N-silylated ; Indoles ; Epoxides, disilylamino- ; Ketones, α-amino ; Indolinones ; Dimethyldioxirane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxygen transfer to the enamines 1a-f by dimethyldioxirane (DMD) in acetone solution leads to the α-amino epoxides 2a-f. The stability of the α-amino epoxides 2a-f depends only on the type of substitution at the nitrogen atom. Thus, while the epoxides 2a, b could be characterized spetroscopically, the epoxidation of the enamines 1c-f resulted in the corresponding α-amino ketone 3c (hydride shift) and the amides 4d-f (alkyl shift). The α-[bis(trimethylsilyl)]amino epoxides 2a, b represent the first observable enamine oxides and emphasize the value of stabilizing such labile epoxides through disilylation of the enamine nitrogen atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251217
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  • 114
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    Electronic Resource
    Chiral Organometallic Reagents, IX. On the Origins of the Diastereoselectivity in the Bromine/Lithium Exchange of 3-Alkoxy-1,1-dibromoalkanes (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2741-2747 
    Details
    ISSN: 0009-2940
    Keywords: Halogen ; metal exchange ; Stereoselectivity ; Conformer populations ; Calculations, MM2 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 3-alkoxy-1,1-dibromopentanes 5 are compounds, which according to MM2 calculations populate one conformation to 〉80% at -110°C. On reaction with n-butyllithium the bromine atom which resides in the extended position is exchanged with selectivities around 80:20, irrespective of the nature of the oxy residue at C-3. The role of this substituent is solely to bias the conformational equilibria in favor of the conformer 17. Coordination of the butyllithium to the oxygen functionality plays an important role only in the carbamoyl derivative 5f, for which the sense of the asymmetric induction is reversed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921251220
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  • 115
    Electronic Resource
    Electronic Resource
    1λ5,3λ5-Diphosphol-Derivate aus Bis(diphenylphosphino)methan und Propargylbromiden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 67-71 
    Details
    ISSN: 0009-2940
    Keywords: Propargylphosphonium ions ; CC-Proton shifts ; 1,3-Diphosphole derivatives, cationic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1λ5,3λ5-Diphosphole Derivatives from Bis(diphenylphosphino)methane and Propargyl BromidesThe two title reagents 2 and 3 form a five-membered 1,3-diphosphole ring by nucleophilic interaction of the two phosphino groups of 2 with the methylene carbon atom and the adjacent acetylenic carbon atom of 3. (Phosphinomethyl)propargylphosphonium, diphosphafulvenium and diphospholium bromides (4, 6, and 1) result and can be isolated from consecutive steps of this reaction. By hydrolysis the diphospholium rings of 1 and 6 are selectively opened at the PCP unit to yield four different isomeric (phosphinoylpropenyl)phosphonium bromides 8 - 11.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250112
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  • 116
    Electronic Resource
    Electronic Resource
    Alkylvanadium- und Alkylniobium-Reagentien, II. Niobium-induzierte reduktive Carbonyldimerisierung (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 149-151 
    Details
    ISSN: 0009-2940
    Keywords: Reductive carbonyl dimerisation ; Niobium pentachloride ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylvanadium and Alkylniobium Reagents, II.  -  Niobium-Induced Reductive Carbonyl DimerisationNbCl5 reacts with one equivalent of methyllithium or metallic potassium to give a reagent for the transformation of aldehydes, ketones, benzalchloride, and benzotrichloride to symmetrically substituted ethene derivatives (Tab. 1). The reagent NbCl5/K (2) is distinctly more reactive than NbCl5/MeLi (1). For the reductive carbonyl dimerisation with niobium reagents a mechanism is proposed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250124
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  • 117
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    Electronic Resource
    Alkylchrom- und Alkylmangan-Reagenzien, IV. Über die Aldehyd- und cheleselektive Alkylierung organischer Carbonylverbindungen mit Monoalkylchrom(III)-Reagenzien (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 157-162 
    Details
    ISSN: 0009-2940
    Keywords: Chromium organo compounds ; Chemoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylchromium and Alkylmanganese Reagents, IV.  -  On the Aldehyde and Cheleselective Alkylation of Organic Carbonyl Compounds with Monoalkylchromium(III) ReagentsMonoalkylchromium(III) reagents, prepared in crystalline form or in solution, alkylate aldehydes but normally not ketones. Ketones with a basic group (HO, MeO, Me2N) in α- or β-position are methylated by MeCrCl2(thf)3, allowing the highly selective («cheleselective») methylation of such ketones in the presence of normal ketones.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250126
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    Collisionally Activated Dissociation of Some Bulkily Substituted Pyridinium Cations, II. Substituent Effect on Appearance Potential (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 177-181 
    Details
    ISSN: 0009-2940
    Keywords: Gas-phase dissociation ; Appearance energies ; Calculations, AM1 ; Pyridinium cations, N-benzyl-2,4,6-substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collisionally activated dissociations (CADs) of various pyridine-ring substituted N-benzylpyridinium cations in the gas phase form the substituted pyridine and benzyl carbocation. Appearance energies (AEs) are estimated quantitatively from the appearance thresholds of the corresponding fragment ion from the laser-desorbed pyridinium cations. MO calculations predict that such unimolecular dissociation processes lead initially to ion-molecule pairs (IMPs): some such IMPs are of significantly lower energy than the fully dissociated products. The AEs have also been compared with the energy differences [ΔΔHf=ΔHf(Py) + ΔHf(R+)  -  ΔHf(Py+R)] determined by AM1 calculations: in many cases these are quite close to the calculated energy differences; discrepancies are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250129
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  • 119
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    Zum Mechanismus der Cyclopropan-“Walk”-Umlagerung: Synthese und Eigenschaften eines optisch aktiven Diazoalkan-Addukts von Toluol; eine hochstereoselektive N2-EliminierungHerrn Professor Horst Prinzbach zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 197-208 
    Details
    ISSN: 0009-2940
    Keywords: Azoles, optically active, thermolysis and photolysis of ; Walk rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mechanism of the Cyclopropane “Walk” Rearrangement: Synthesis and Properties of an Optically Active Diazoalkane-Toluene Adduct; a Highly Stereoselective N2 EliminationThe synthesis and the thermal and photochemical behavior of the optically active 2-diazo-1-methoxypropane-toluene adduct 3 are reported. The N2 elimination of 3 ocurs with one and the same stereochemical course upon thermolysis as well as direct photolysis: 7-(Methoxymethyl)-1,7-dimethyl-1,3,5-cycloheptatriene (1) is formed with retention of configuration at C-7 and 7-(methoxymethyl)-2,7-dimethyl-1,3,5-cycloheptatriene (2) with inversion of configuration at C-7. These stereochemical findings are explained by an intermediary singlet diradical 1[4] in which the ring closure between C-1 and C-7 or C-5 and C-7 is faster than the rotation around the single bond between C-6 and C-7. In the case of the thermally induced formation of 2 a concerted N2 elimination has to be considered as a competitive pathway. The results presented here are well in accord with the stereochemical analysis of the cyclopropane “walk” rearrangement 1⇋2 reported previously and are therefore a good evidence that the diradical intermediate 4 is also involved in the “walk” rearrangement. In the photochemically induced N2 elimination of 3, sensitized by benzophenone and leading again to 1 and 2, a surprisingly high degree of stereoselectivity is observed. Thus, the intermediary triplet diradical 3[4] must have a much shorter life time than ordinary 1,3-diradicals in the triplet state.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250132
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    Hydrierwärmen, IV. Zur Frage der Homoaromatizität von Norcaradien und Cycloheptatrien (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 217-224 
    Details
    ISSN: 0009-2940
    Keywords: Homoaromaticity ; Resonance energy ; Calculations, force-field ; Heats of hydrogenation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heats of Hydrogenation, IV.  -  Homoaromaticity in Norcaradiene and CycloheptatrieneBy comparison of the heats of hydrogenation of fixed norcaradienes with analogous cyclobutane derivatives and from the difference of experimental heats of formation with values calculated by force-field methods the homoaromatic stabilization of norcaradienes and cycloheptatrienes are calculated and compared with the equilibrium position of the respective valence isomers.
    Additional Material: 9 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250134
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  • 121
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    Synthese von 1,2-Dioxolanen durch Ozonolyse 1,1-disubstituierter nichtaktivierter Olefine (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 191-195 
    Details
    ISSN: 0009-2940
    Keywords: Ozonolysis ; Alkylidenecycloalkanes ; Carbonyl oxides ; 1,2-Dioxolanes ; 1,2,4-Trioxolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 1,2-Dioxolanes by Ozonolysis of 1,1-Disubstituted Nonactivated OlefinsOzonolyses of the cyclopropyl-substituted olefins 2a, 2b, and 2c do not produce the carbonyl oxides 1a, 1b, and 1c but formaldehyde oxide (1d); 1d can be trapped by the starting olefin and provides the 1,2-dioxolanes 6a, 6b, and 6c, respectively, in ca. 10% yield. Other dioxolanes and normal ozonides may be obtained by the addition of olefins or aldehydes to solutions of the primary ozonides of 2a and 2b.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250131
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  • 122
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    Wasserstoffübertragungen, 19. Zur Katalyse von Wasserstoff-Transfer und 1,5-H-Shift durch Rhodium(III)-chlorid in homogener organischer Phase (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 209-215 
    Details
    ISSN: 0009-2940
    Keywords: Rhodium chloride ; Hydrogen transfer ; Deuterated 1,3-cyclohexadienes ; Isotope effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen Transfer Reactions, 19.  -  The Catalysis of Hydrogen Transfer and 1,5-H Shift by Rhodium(III) Chloride in Homogeneous Organic SystemsIn homogeneous solution, partly in the presence of a phase-transfer catalyst, rhodium(III) chloride catalyzes the disproportionation of 1,3-cyclohexadiene and to a lesser extent 1,5-H shifts. In the start phase the catalyst is reduced to the active monovalent state. In these catalytic systems the dehydrogenation proceeds stereoselectively. - This was shown by tracer experiments and isotopes effects using deuterated 1,3-cyclohexadienes 1a - d, which were synthesized with high isotopomeric purity.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250133
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  • 123
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    Phosphinalkylene, 50. Zur Struktur von 2,2,2-Triphenyl-1,2λ5-oxaphospholanen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 225-229 
    Details
    ISSN: 0009-2940
    Keywords: Phosphorus, tetra- and pentacoordinate ; Oxaphospholanes ; Trigonal-bipyramidal structure ; Equilibrium of ring and betain structure in polar solvent ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphine Alkylenes, 50.  -  On the Structure of 2,2,2-Triphenyl-1,2λ5-oxaphospholanes2,2,2-Triphenyl-1,2Δ5-oxaphospholanes (5a - h) were synthesized from methylene-triphenylphosphorane (1, R=H) and suitable epoxides (2a - g). Oxaphospholane 5e was subjected to an X-ray structural analysis, which showed a five-membered ring-structure with a trigonal-bipyramidal coordinate phosphorus atom. One phenyl group and the ring oxygen atom are apical ligands at phosphorus. According to the NMR spectra, oxaphospholanes have a ring structure in nonpolar solvents, whereas in polar solvents there exists an equilibrium with an open-chain form.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250135
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  • 124
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    Epoxidation of 2,3-Dimethylbenzofurans by Dimethyldioxirane (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 231-234 
    Details
    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxirane, dimethyl ; Benzofurans, 2,3-dimethyl- ; Benzofuran epoxides ; Quinone methides ; Methanol addition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of epoxides 2 by the reaction of the chloro- and methyl-substituted 2,3-dimethylbenzofurans 1 with dimethyl-dioxirane at low temperature is reported. These labile epoxides were spectroscopically characterized (1H and 13C NMR) at subambient temperatures. Epoxidation of benzofuran 1c affords a 31:69 mixture of epoxide 2c and quinone methide 3c, the latter presumably being produced by valence isomerization of the epoxide. On warming up above -10°C, the epoxides 2 suffer decomposition. Treatment of epoxide 21 with methanol yields the tautomeric mixture of adducts 4i and 4i′.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250136
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  • 125
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    Struktur und Reaktivität von Bis(π-pentamethylcyclopentadienyl)-(2-methyliden)titanacyclobutan (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 291-299 
    Details
    ISSN: 0009-2940
    Keywords: Titanacyclobutane complexes ; Vinylidene intermediates ; Titanium complexes ; MO theory, applied ; Cycloreversion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure and Reactivity of Bis(π-pentamethylcyclopentadienyl)(2-methylidene)titanacyclobutaneThe reaction of vinyllithium with bis(π-pentamethylcyclopentadienyl)titanium dichloride in a molar ratio of 2:1 quantitatively yields the unexpected titanacyclobutane derivative (2) (Cp* = [C5(CH3)5]). The isolated complex 2 has been characterized by spectroscopic methods and by elemental analysis, and its structure has been confirmed by an X-ray structure determination. The chemical reactivity of 2 is characterized by the splitting of the four-membered ring at higher temperatures, forming a titanocene vinylidene fragment {Cp2*Ti = C = CH2} and ethylene. This cycloreversion is confirmed by the fragmentation behavior in the mass spectrometer, and some aspects of it have been studied by Extended Hückel Model calculations.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250204
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    2-{[2-(Dimethylamino)ethyl]methylamino}-1,3,2-benzodioxaphosphol als Ligand in Übergangsmetallkomplexen  -  Kristall- und Molekülstruktur eines Tetracarbonylchrom-Komplexes (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 301-307 
    Details
    ISSN: 0009-2940
    Keywords: Ethylenediamine, N,N,N′-trimethyl- ; Transition-metal complexes, P - N coordination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-{[2-(Dimethylamino)ethyl]methylamino}-1,3,2-benzodioxaphosphole as a Ligand in Transition-Metal Complexes. Crystal and Molecular Structure of a Tetracarbonyl Chromium DerivativeComplexes of the zerovalent transition metals chromium, molybdenum, iron, and platinum react with the title phosphorus-(III)-compound 3 to give a range of different products: in the coordination compounds 4 and 5, 3 functions as a bidentate ligand, coordinating to the metal through the phosphorus and the nitrogen atom of the dimethylamino group. The structure of 4 was confirmed by a single-crystal X-ray analysis, showing a ligand “bite” angle of 91.0, 91.4° in two independent molecules. In the compounds 7 - 9, involving Mo, Fe, and Pt as a central atom, 3 coordinates solely through P(III). For the platinum(O) complex 9 31P-NMR spectroscopy revealed a dynamic behaviour at room temperature.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250205
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    Zum Kenntnisstand der 1,3,5-Triaza-2,4-diphospha-1,4-pentadieneHerrn Professor Heinrich Puff zum 70. Geburtstag gewidmet (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 321-330 
    Details
    ISSN: 0009-2940
    Keywords: Phosphanes, (Z)-amino(imino)- ; 1,3,5-Triaza-2,4-diphospha-1,4-pentadienes, transition metal complexes of, dynamic behavior of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Knowledge of the 1,3,5-Triaza-2,4-diphospha-1,4-pentadienesHerrn Professor Heinrich Puff zum 70. Geburtstag gewidmetNucleophilic substitution reactions of the chloro(arylimino)-phosphane 1 yield the NH-functional amino(imino)phosphanes Mes*NPNHR (R = Mes, Ad, CPh3) 2d - f. Upon further reaction with 1 they are converted into the 1,3,5-triaza-2,4-diphospha-1,4-pentadienes Mes*NPN(R)PNMes* (R = Mes, Ad) 4d, e and Mes*NPN(Mes*)PNCPh3 5. According to crystal structure determinations all compounds 4a, d, e, 5 exhibit S conformation in the solid state. In addition to the “exo-endo” arrangement of the substituents (4a, 5) in the case of 4d, e the “endo-endo” conformation is observed for the first time. In solution, 4d, e and 5 are subject to dynamic rearrangements, whose mechanism is proven by NMR studies of partially 15N-enriched samples. The reaction of 4a with NorM(CO)4 (M = Cr, Mo) or Ni(CO)4 yields the metallaazadiphosphetidine complexes 6a - c Mes*NPN(tBu)PNMes*M(CO)n [M(CO)n = Cr(CO)4, Mo(CO)4, Ni(CO)2]. The crystal structure of 6a (“exo-endo-W”) is described.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250208
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    Bis(cyclopentadienyl)methan-verbrückte Zweikernkomplexe, IV. Synthese, Struktur und Reaktivität von Zweikernkomplexen des Rhodiums und Iridiums in der Oxidationsstufe +I und +III mit dem Bis(cyclopentadienyl)methan-Dianion als Brückenliganden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 337-346 
    Details
    ISSN: 0009-2940
    Keywords: Dinuclear rhodium and iridium complexes ; Bis(cyclopentadienyl)methane dianion as bridging ligand ; Substitution and bridge-splitting reactions ; Rhodium complexes ; Iridium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(cyclopentadienyl)methane-Bridged Dinuclear Complexes, IV[1].  -  Synthesis, Structure, and Reactivity of Dinuclear Rhodium and Iridium Complexes in the Oxidation State +I and +III with the Bis(cyclopentadienyl)methane Dianion as Bridging LigandThe rhodium compounds [CH2(C5H4)2][Rh(L)(C2H4)]2 (2, 4) were prepared from [RhCl(L)(C2H4)]2 (1, 3) and CH2(C5H4)2Li2 in 92 and 73% yield, respectively. The reaction of 4 with Cl2, Br2, and I2 led to the almost quantitative formation of the dihalogeno derivatives [CH2(C5H4)2][RhX2(PiPr3)]2 (6-8), which on treatment with excess NaBH4 and methanol gave the dihydride [CH2(C5H4)2][RhH2(PiPr3)]2 (10). From [RhCl(C8H14)2]2 (12), PiPr3, and CH2(C5H5)2 the chloro(hydrido)rhodium complex [CH2(C5H4)2][RhH(Cl)(PiPr3)]2 (13) was obtained. Protonation of 10 with CF3CO2H in the presence of NH4PF6 gave the PF6 salt of the hydrido-bridged cation {[CH2(C5H4)2]-[RhH(PiPr3)]2(μ-H)}+ (14) of which the crystal structure was determined. In solution, fluxional behavior of the cation was observed. The dimethyl compound [CH2(C5H4)2][Rh(CH3)2-(PiPr3)]2 (17), prepared from 6, 7, or 8 and LiCH3 or CH3MgI in 80% yield, reacted with CF3CO2H at  -  78° C to give the tri-fluoroacetato derivative 18; this on treatment with P(OMe)3 and dmpe formed the dicationic complexes 19 and 20, respectively. The dinuclear iridium compounds [CH2(C5H4)2]-[Ir(olefin)2]2 (26, 27) and [CH2(C5H4)2][Ir(C8H12)]2 (28) were prepared from [IrCl(L)2]2 (23-25) and CH2(C5H4)2Li2 and used for the synthesis of {[CH2(C5H4)2][IrX2]2}n (29, 30). Compounds 29 and 30 served as starting materials for the preparation of the dinuclear derivatives [CH2(C5H4)2][IrX2(L)]2 (31-34) and {[CH2(C5H4)2][IrBr2]2(μ-dipy)} (35) and finally also for the dihydrido complex [CH2(C5H4)2][IrH2(PiPr3)]2 (36).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250210
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    Bis(di-tert-butylphosphanyl)methan-Komplexe des Rhodiums: Geometrie, Elektronenstruktur und Derivate des 14-Elektronenteilchens [Rh(dtbpm)Cl]. Molekülstruktur von Rh(dtbpm)Cl(PMe3) (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 353-365 
    Details
    ISSN: 0009-2940
    Keywords: Rhodium(I) phosphane complexes ; 14-Electron intermediates ; MO theory, applied ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(di-tert-butylphosphanyl)methane Complexes of Rhodium: Geometry, Electronic Structure, and Derivatives of the 14-Electron Fragment [Rh(dtbpm)Cl]. Molecular Structure of Rh(dtbpm)Cl(PMe3)14-Electron fragments [M(PR3)2X] (M = Rh, Ir, X = halogen etc.) are considered to be an important class of highly reactive, coordinatively unsaturated intermediates in many metal-induced stoichiometric or catalytic transformations of organic substrates. As available theoretical data suggest a slightly preferred T-shaped groundstate geometry with a less symmetric cis rather than the usually implied trans phosphane arrangement for such tricoordinate d8-ML3-type systems with monodentate phosphanes PR3, the chemistry of η2-diphosphanylmethane complexes of rhodium with four-membered RhPCP-chelate rings and thus with enforced cis phosphane coordination and anomalously small cis P - Rh - P angles has been studied by theory and by experiment. MO calculations (EH) have been performed both for the model 14-electron system [Rh(dhpm)Cl] (dhpm = diphosphanylmethane, H2P - CH2 - PH2) and for the experimentally accessible fragment [Rh(dhbpm)Cl], where dtbpm is bis(di-tert-butylphosphanyl)-methane, (tBu)2P - CH2 - P(tBu)2. The electronic and geometric structure of these species is described. Employing the unusual ligand dtbpm, tailor-made for stabilizing mononuclear η2- and destabilizing dinuclear μ-diphosphanylmethane coordination, the chloro-bridged dimer [Rh(dtbpm)Cl]2, has been synthesized. In agreement with steric and electronic considerations, its chemistry is dominated by a facile dissociation to monomeric (presumably solvent coordinated) fragments [Rh(dtbpm)Cl], even in benzene, as suggested by molecular mass determinations. Accordingly, by using [Rh(dtbpm)Cl]2 as a starting material, a series of sterically very congested but nevertheless mononuclear, square-planar complexes Rh(dtbpm)Cl(L) (L = CO, PMe3, PPh3, PCy3, pyridine, acrylonitrile) with chelating dtbpm could be readily prepared and fully characterized. The relative stability of these potential alternative precursors of a [Rh(dtbpm)Cl] intermediate towards dissociation of ligands L is reported. The molecular structure of Rh(dtbpm)Cl(PMe3) as the first representative of this class of compounds has been determined by X-ray crystallography.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250212
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    Synthese und Struktur von Bis(trimethylstannyl)- und Bis(dimethylhalogenstannyl)aminen: zur Rolle des Stickstoff-Elektronenpaares (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 389-400 
    Details
    ISSN: 0009-2940
    Keywords: Amines, bis(trimethylstannyl)organyl-, bis(dimethylhalostannyl)organyl- ; Bond cleavage, SnN ; 1,3,2,4-Diazadistannetidine, hexamethyl- ; N.N′-Bis(dichlorodimethylstannane) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Bis(trimethylstannyl) and Bis(dimethylhalostannyl) Amines: The Role of the Nitrogen Lone PairMonoaminostannanes RNH -  SnMe3 (1) with substituents R = tBu, Mes, 2,6-iPr2C6H3 are obtained by transmetallation from Me3SnX and RNH - Li, the distannylamines RN(SnMe3)2 (2) by transamination of Et2N  - SnMe3 with RNH2, and bis(dimethylhalostannyl)amines R - N(SnMe2X)2 (8) by stannazane cleavage of 2 with Me2SnX2 or by SnC cleavage with BX3 (8n, o). Me2Sn(NtBuH)2, prepared from tBuNHLi and Me2SnBr2, decomposes with tBuNH2 elimination into the diazadistannetidine 4 already below room temperature. Information from multinuclear NMR spectra of type 2, 4, and 8 compounds ascertain the proposed relation between the value of the geminal coupling constant 2J(119Sn117Sn) of distannazanes and the Sn - N - Sn bond angle as determined by the X-ray structure analysis of 2c and of (8a)2 as well as the participation of the electron pair at the nitrogen atom in bonding. 2c has C2 symmetry, contains a planar nitrogen atom with SnN bond lengths of 2.044 Å and an Sn - N - Sn bond angle of 125.0°. The aryl group stands perpendicular to the Sn2N plane. These data exclude any π interaction between the N atom and the substituents. 2c, therefore, represents an example of a tertiary amine with the lone electron pair at the nitrogen atom in a p-type orbital. The supposed distannylamine (ClMe2Sn)2NMe (8a) is actually a dimer, whose unexpected structure contains a diazadistannetidine unit bearing two Me2SnCl2 groups at its nitrogen atoms in cis-configuration. This arrangement allows the formation of weak intramolecular SnCl bonds.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250216
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    A Contribution to the Direct Observation of a Didehydroheteroaromatic with a Five-Membered Ring: 2,3-DidehydrothiopheneDedicated to Professor Günther Maier on the occasion of his 60th birthday. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 423-431 
    Details
    ISSN: 0009-2940
    Keywords: Matrix isolation ; Photolysis ; Vibrational spectra, theoretical ; 2,3-Didehydrothiophene ; Calculations, ab initio, semi-empirical ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The flash vacuum pyrolysis and the photolysis of 2,3-thiophenedicarboxylic acid anhydride (6) were investigated by using the technique of matrix isolation combined with FT-IR spectroscopy. No conclusive proof for the existence of 2,3-didehydrothiophene (1) could be found, but two hitherto unknown isomers were isolated and characterized: vinylidenethioketene (10) and thioformylvinylidenecarbene (15).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250221
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    1,2,4-Oxadithietane und ein 1,2,4-Oxadithiet (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 557-561 
    Details
    ISSN: 0009-2940
    Keywords: Oxadithietanes ; Oxadithiete ; Sulfur trioxide ; addition across CC und CS double bonds ; CS double bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2,4-Oxadithietanes and a 1,2,4-OxadithieteSO3 adds to (pentafluoro-λ6-sulfanyl)ethenes 2 with formation of 1,2-oxathietane 1 and 1,2,4-oxadithietanes 3. The latter class of compounds (examples 4a, b) can also be obtained from SO3 and alkylidenesulfur tetrafluorides F3C-RC = SF4. HOSO2F elimination from 3 affords 3-methylene-1,2,4-oxadithietanes 5. HF elimination from 4a occurs within the ring, resulting in the first oxadithiete 6. This isomerizes upon heating to an alkylidenesulfur difluoride oxide FSO2(F3C)C=SF2=O.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250305
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    Verbindungen des Germaniums und Zinns, 10[1] Thermolyse eines Cyclotristannans: Stannylen- versus Distannen-Reaktionen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 563-566 
    Details
    ISSN: 0009-2940
    Keywords: Stannylene, bis(2,4,6-triisopropylphenyl)- ; Distannene, tetrakis(2,4,6-triisopropylphenyl)- ; 1,2-Distannacyclobutene derivative ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Compounds of Germanium and Tin, 10[1].  -  Thermolysis of a Cyclotristannane: Stannylene versus Distannene ReactionsHexakis(2,4,6-triisopropylphenyl)cyclotristannane (1), first described by Masamune and Sita, is easily accessible by treatment of tin(II) chloride with 2,4,6-triisopropylphenylmagnesium bromide. The equilibrium between 1 and its cleavage products bis(2,4,6-triisopropylphenyl)stannylene (2) and tetrakis(2,4,6-triisopropylphenyl)distannene (3) in toluene has been followed by 119Sn-NMR spectroscopy at elevated temperatures. Stannylene 2 can be trapped by open-chain or cyclic diketones as well as by 1,3-dienes. Reaction of 3 with phenylacetylene proceeds in a [2 + 2] fashion to provide the 1,2-distannacyclobutene derivative 5 whose structure was confirmed by X-ray crystallography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250306
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  • 134
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    Reaktionen von Halogenthiazylen: Darstellung, Strukturen und Eigenschaften von perhalogenierten 1,2-Thiazinen[1] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 581-589 
    Details
    ISSN: 0009-2940
    Keywords: [4 + 2] Cycloadditions ; Thiazyl compounds ; 1,2-Thiazines ; 1,2-Thiazin-1-ium hexafluoroarsenates ; 1λ4,2-Thiazine, 1-chloro-3,3,4,5,6,6-hexafluoro-3,6-dihydro-, crystal structure of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Halogeno Thiazyls: Preparation, Structures, and Properties of Perhalogenated 1,2-ThiazinesReactions of (XSN)n (n = 1,3; X = F, Cl) with perfluorobutadiene provide the 1λ4,2-thiazines 1a and 1b. The structure of 1 b was determined by single-crystal X-ray diffraction analysis. From the molecular structure it is evident that a formal [4 + 2] cycloaddition has occured. Fluorination with KF converts 1 b almost quantitatively into 1 a. The 1λ4,2-thiazine 1 a does not exhibit fluorinating properties towards chloroalkanes but undergoes reaction with CH3OH and Me3SiNMe2 to form 1 c and 1 d, respectively. 1,2-Thiazine oxide 3 is obtained from 1 a or 1 b and (Me3Si)2O. Treatment of 1 b with AgAsF6 in SO2 yields perfluoro-1,2-thiazin-1-ium hexafluoroarsenate (4) as the main product. No reaction is observed between FSN and hexa-chlorobutadiene. The 1,2-thiazines 5, 6, and 9 are prepared from tetrachlorothiophene dioxide (7) and FSN. Fluorine abstraction reactions of 5 and 6 with formation of the expected 1,2-thiazin-1-ium ions 11 and 13, respectively, provide evidence for the structures of 5 and 6. These cations are very sensitive to hydrolysis and are converted into the corresponding ketones 12 and 14. The very unstable intermediate CF3SSN, formed on treating Me3SiSCF3 or B(SCF3)3 with FSN, decomposes to CF3SxCF3 (X = 2-4), S4N4, S8, and N2. No addition product can be detected when CF3SSN prepared in situ is treated with dienes.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250309
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    Kristallstruktur, Festkörperpolymerisation und Ionenleitung in Alkalisalzen ungesättigter Carbonsäuren, 2[1] Untersuchungen an Lithiummethacrylat und Lithiummethacrylattritonmethanolat (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 613-616 
    Details
    ISSN: 0009-2940
    Keywords: Methacrylate, lithium salts ; Polymerization, solid-state ; Conductivity, ionic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal Structure, Solid-State Polymerization, and Ionic Conductivity of Alkali Salts of Unsaturated Carboxylic Acids, 2[1].  -  Investigations on Lithium Methacrylate and Lithium Methacrylate TritonmethanolateThe structures of lithium methacrylate C4H5O2Li (1) and the corresponding lithium methacrylate tritonmethanolate C4H5O2Li · 1/3 CH3OH (2) have been determined by singlecrystal X-ray diffraction. Compound 1 is built up by inorganic layers - a two-dimensional network of corner- and edge-shared LiO4 tetrahedra - and organic double layers with a hydrophobic interaction of zipper-like arranged methacrylate groups. The crystal structure of compound 2 can also be envisaged as a layered structure where „inorganic” and „organic” blocks alternate. Here edge- and cornershared LiO4 tetrahedra extend in zig-zag chains along [010] which are bridged by carboxyl groups. The compound is an ionic conductor. - In both compounds the distances between the functional groups are too large for a diffusionless topochemical polymerisation. Polymerisation takes place thermally between 200 and 290°C. It can also be induced by UV irradiation in the presence of benzoin.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250312
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  • 136
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    Ergänzung (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 663-663 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250320
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  • 137
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    Some Unusual Reactions of 1,2-Bis(phenylethynyl)benzene with Sulfur, Carbon Monoxide and Alkyl Acetylenedicarboxylates (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 667-674 
    Details
    ISSN: 0009-2940
    Keywords: Benzene, 1,2-bis(phenylethynyl)- ; Diyne cycloaddition ; Rhodium catalyst ; Platinum catalyst ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Bis(phenylethynyl)benzene (1) reacts with sulfur, carbon monoxide, and acetylenedicarboxylic esters to give unusual polycyclic products. Under exclusion of air 1 adds sulfur to give 6-phenylbenz[b]indeno[2,1-d]thiopyran (3b) and bis(6-phenylbenz[b]indeno[2,1-d]thiopyran-11-yl) disulfide (4). In the presence of air 3-benzoyl-2-phenyl-1H-inden-1-one (5) is formed via a sulfur-containing intermediate. Under phase-transfer conditions [CH3N(C8H17)3]+ [RhCl4(H2O)2]- promotes reductive carbonylation of 1 to give initially the lactones 3,8-dihydro- and 8,8a-dihydro-3-phenyl-8-(phenylmethylene)-2H-indeno[2,1-b]furan-2-one (6 and 7) which isomerize to 3-phenyl-8-(phenylmethyl)-2H-indeno[2,1-b]furan-2-one (8). Interaction of 1 and MeO2CC≡CCO2Me in the presence of the same rhodium catalyst results in crosscyclooligomerization in which tetramethyl 2-(phenylethynyl)-1,1′:2′,1′'-terphenyl-3′,4′,5′,6′-tetracarboxylate (9) is obtained. The H2PtCl6-Aliquat-336 catalyst promotes the reaction of 1 with equimolar amounts of RO2CC≡CCO2R (R = Me, Et, Pr) to give the corresponding (Z)-2-(10-phenylindeno[2,1-α]inden-5-yl)-2-butendioates (11a-c). The structures of 3b, 4, 5, 8, and 11a have been determined by X-ray diffraction analyses. Possible routes for the transformation of 1 into the polycyclic products are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250321
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    Fluor- und FluoroxodithietaneHerrn Professor Anton Meller zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 535-539 
    Details
    ISSN: 0009-2940
    Keywords: Dithietanes, fluoro- and fluorooxo-; formation of, cleavage with halogen fluorides, gas phase structure ; Lewis acids, containing fluorine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fluoro- and Fluorooxodithietanes (1) was isolated from the reaction of 2,2,4,4-tetrafluoro-1,3-dithietane (3) with CIF in an unpassivated monelcylinder. The hydrolysis of 1 gives (2): the trans derivative (2b) and the cis isomer (2a) are formed in a 4:1 ratio. (7) is oxidized by CIF at room temperature to give the known (8) in 87% yield. At 50°C from 8 and (9) is formed besides the ring cleavage products CF3SO2CF2SF4Cl (10) and CF3SO2CF2SF5 (11). The gasphase structure of 9 (e.d.) is described. (5) and (13) coordinate by the oxygen of the SO group to AsF5, with an unstable sulfonium salt is formed, while from the reaction of AsF5 and SbF5 with 8 (15 a, b, M = As, Sb) are isolated.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250302
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  • 139
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    Organophosphorverbindungen, 53[1] Cyclopropenyliden-methylen-diphosphane - neue gekreuzt konjugierte Phosphapolyene[2] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 729-732 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaalkenes ; Phosphatriafulvenes ; Cross-conjugated phosphapolyenes ; Diphosphanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organophosphorus Compounds, 53[1]. - Cyclopropenylidene-methylene-diphosphanes - New Cross-Conjugated Phosphapolyenes[2]The reaction of chloromethylenephosphanes 7 with the inverse cyclopropenylidenephosphanes 6, 10 leads to the formation of the title compounds 8 and 11 as a new class of cross-conjugated phosphapolyenes. The structure of compound 8a has been confirmed by an X-ray structural analysis.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250328
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    Masthead (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250401
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  • 141
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    Structural NMR Investigations on Allyllithium Compounds (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 733-737 
    Details
    ISSN: 0009-2940
    Keywords: Allyllithium compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four differently substituted phenylallyllithium compounds Li · 2 have been investigated by dynamic 1H- and 13C-NMR, NOESY and HOESY spectroscopy. It is shown that a considerable barrier of rotation (ca. 40 kJ/mol) between the phenyl and the allyl moiety exists which is only slightly affected by the addition of TMEDA. The lithium atom prefers a bridged position with respect to the allylic part in solution and has HOESY contacts to the ortho hydrogen atoms of the aromatic ring.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250329
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  • 142
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    Kurzmitteilung/Short Communication Solvent-Free [1.1.1]Propellane from 1,3-Diiodobicyclo[1.1.1]pentane (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 757-758 
    Details
    ISSN: 0009-2940
    Keywords: [1.1.1]Propellane ; Iodine, nucleophilic attack at ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [1.1.1]Propellane (1) could be prepared free of solvent by reaction of 1,3-diiodobicyclo[1.1.1]pentane (3) with sodium cyanide in dimethyl sulfoxide (DMSO). Highly pure 1 was obtained in an overall yield of more than 50% related to the propellane precursor 1,1-dibromo-2,2-bis(chloromethyl)cyclopropane (2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250332
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  • 143
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    Spaltung sperriger Diarylditelluride mit Brom und Iod[1]; Strukturbestimmung an Et4N+ 2,4,6-(i-C3H7)3C6H2TeI-2 (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 761-766 
    Details
    ISSN: 0009-2940
    Keywords: Tellurium compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cleavage of Bulky Diaryl Ditellurides with Bromine and Iodine; Crystal Structure of Et4N+ 2,4,6-(i-C3H7)3C6H2TeI-2Bis(2,4,6-triisopropylphenyl) ditelluride (1a), obtained from 2,4,6-triisopropylphenylmagnesium bromide with tellurium followed by oxidation with oxygen, and bis(2,4,6-tri-tert-butylphenyl) ditelluride (1b) react with equimolar amounts of bromine and iodine to provide new monomeric arenetellurenyl halides 2,4,6-R3C6H2TeX (2a, b, 3a, b: R = i-C3H7, t-C4H9; X = Br, I). Both tellurenyl iodides are thermally more stable than the corresponding bromides. Green 2,4,6-(i-C3H7)3C6H2TeI (3a) reacts with Et4N+I- to give the stable, red adduct Et4N+ 2,4,6-(i-C3H7)3C6H2TeI-2 (4a). An X-ray crystal structure determination of 4a revealed a T-shaped structure of the hypervalent aryldiiodotellurate(II) anion. Iodide-ion transfer between aryldiiodotellurate(II) and arenetellurenyl iodide is a fast process (1H-NMR time scale). 125Te-NMR data of this anion and of tellurenyl halides are compared with those of the ditellurides and of lithium benzenetellurolates (LiTeR·(THF)x).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250402
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    Synthesis, Structure, and Reactivity of Chiral Rhenium Amido Complexes of the Formula (η5-C5H5)Re(NO)(PPh3)(NRR') (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 815-824 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium complexes ; Amido ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of primary and secondary amine complexes [(η5-C5H5)Re(NO)(PPh3)(NHRR')]+ TfO- [2; R/R' = H/H (a), H/CH3 (b), H/C6H5 (d), CH3/CH3 (f), CH2CH2CH2CH2 (h)] with nBuLi give amido complexes (η5-C5H5)Re(NO)(PPh3)(NRR') (1) in quantitative NMR yields. Although 1 d can be isolated in pure form, 1 f is converted upon workup into a dimeric bridging bis(amido) complex, cis-[(η5-C5H5)Re(NO){μ-N(CH3)2}]2. The crystal structure of 1 d exhibits a pyramidal amido nitrogen atom. The diastereotopic methyl groups in 1 f readily exchange, as assayed by variable-temperature NMR. Complexes 1 a, f react with TfOH to regenerate 2a, f, and with TfOR” to give the corresponding alkylated amine complexes. The basicities and nucleophilicities of the amido nitrogen atoms are shown to be greater than those of organic amines.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250410
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    Synthese und Strukturen von (Monoorganyl)amiden und -imiden des Zirkoniums und Hafniums (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 825-831 
    Details
    ISSN: 0009-2940
    Keywords: Zirconium amides, imides ; Hafnium amides, imides ; Amides ; Imides ; ZrN double bond ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structures of (Monoorganyl)amides and -imides of Zirconium and HafniumThe tetrahalides MCl4 (M = Zr 1 a, Hf 1 b) react with LiNHtBu with elimination of LiCl to yield [(tBuNH)2MNtBu]2 (3) (M = Zr 3a, Hf 3b). Compounds 3 are thermally instable and oli-gomerise above 100 °C with elimination of H2NtBu. The reactions of (η5-C5Me5)MCl3 (M = Zr 1 c, Hf 1 d) with LiNHR (R = tBu 2 a,2,4,6-Me3C6H2 2 b, 2, 6-iPr2C6H3 2 c) lead to (η5-C5Me5)M(NHR)3 (4) (R = tBu, M = Zr 4 a, Hf 4 b; R = 2, 4,6-Me3C6H2, M = Zr 4 c, Hf 4 d; R = 2,6-iPr2C6H3, M = Zr 4 e, Hf 4 f). Compounds 4 are thermally very stable and melt without decomposition. When 1 c and 1 d react with LiNHPh (2 d), dimers of composition [(η5-C5Me5)M(NHPh)NPh]2 (M = Zr 5 a, Hf 5 b) are obtained. The complexes (η5-C5Me5)2MCl2 (M = Zr 1 e, Hf 1 f) react with 2 b to form (η5-C5Me5)2M(NHR)2 (6) (M = Zr 6 a, Hf 6 b). Pyridine reacts with 4 e at 85 °C and replaces one molecule of 2,6-iPr2C6H3NH2 to give (η5-C5Me5)Zr-(NHR)NR · Py (7). The single crystal X-ray structures of 4 a, 4 f, 5 b and 7 are described.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250411
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    Helical Phenanthrenes, 3[1] Syntheses, Enrichment of Enantiomers, and Barriers to Racemization of Twisted 9, 10-PhenanthrenequinonesDedicated to Professor Jürgen Sauer on the occasion of his 60th birthday. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 849-855 
    Details
    ISSN: 0009-2940
    Keywords: 9, 10-Phenanthrenequinones ; Acyloin condensation ; Enantiomers, liquid chromatography of ; Barriers to racemization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The known syntheses of the 9, 10-phenanthrenequinones 10a - c were improved by the chlorotrimethylsilane modification of the acyloin condensation of biaryl diesters. The novel quinones 4a, 4b, and 12 were prepared. For the first time, enantiomers (M and P) of this class of compounds were enriched semipreparatively by liquid chromatography on optically active sorbents. The barriers to thermal racemization amount to 90 - 130 kJ mol-1 (Table 2) and are thus higher than the barriers for the corresponding phenanthrene hydrocarbons by roughly 20 kJ mol-1. The reasons for this increase are discussed in terms of repulsive interactions in the transition state of helix inversion.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250416
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    Stereoelectronic and Steric Effects in the Synthesis and Recognition of Diastereomeric Ethers by NMR and EPR SpectroscopyHerrn Professor Ernst Buyer zum 65. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 857-865 
    Details
    ISSN: 0009-2940
    Keywords: Quinone methides ; Stereoelectronic effects ; Chiral recognition ; EPR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (2,6-Di-tert-butyl-4-hydroxyphenyl)-alkyl-carbinols I are easily dehydrated in the presence of catalytic amounts of a mineral acid to form the corresponding phenyl-alkyl-carbocations Ia. These cations can be reversibly deprotonated to the quinone methides Ib, therefore, an equilibrium between both reactive compounds is assumed. In the absence of nucleophiles a reaction of these intermediates with the starting carbinol is observed leading to symmetrical ethers Id. In alcoholic solution the solvent acts as a nucleophilic compound and the formation of an unsymmetrical ether Ie is observed predominantly. If the nucleophile contains a chiral carbon atom diastereomers are formed in this reaction which are observed in variable concentrations depending on the reaction time. The assignment of these isomers to the meso and racemic compound has been achieved by NMR investigations in solution in combination with their solid-state structures determined by X-ray crystallography. These results indicate a remarkable thermodynamic stabilization of the symmetrical ethers in the racemic form whereas the meso compounds are favored if the products are formed under kinetic control. In both cases the diastereomer ratio is determined by steric repulsion and the generalized anomeric effect. - A bonding interaction of lone pairs of the ether oxygen with the π system of the corresponding phenoxyl ring was also observed by EPR investigations. This electron delocalization contributes remarkably to the mechanism responsible for the distinction of the diastereomeric radicals by different β-proton coupling constants.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250417
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    Synthesis and Methylation of Two Differently Fused Benzologs of Pyrido[1,2-b]pyridazinium-4-olate (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 929-932 
    Details
    ISSN: 0009-2940
    Keywords: Zwitterions, heteroaromatic ; Lone electron pair density, role in alkylations ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The alkylation of the two differently fused tricyclic zwitterions 3 and 5 was compared. The linear system 3 was converted into the N-methyl salt 4 on treatment with dimethyl sulfate and into the O-methyl product 12 on treatment with Meerwein's reagent. The angular system 5, in turn, was predominantly transformed into the O-methyl product 14. Theoretical considerations on modified FMO treatment taking into account the lone-pair densities (cn-HOMO) suggested that linear 3 was methylated only at the oxygen position (affording 12) and 4 is a thermodynamically controlled remethylation product. A critical interpretation of cn-HOMO vs. c-HOMO is discussed.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250426
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    Remarkable Effect of Fluorine and Chlorine Atoms on the Stability of 1H-Phosphirene (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 923-927 
    Details
    ISSN: 0009-2940
    Keywords: 1H-Phosphirenes ; 2H-Phosphirenes ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO calculations at the MP4/6-31G** level show that both fluorine and chlorine atoms exert a strong stabilizing effect on the three-membered ring 1H-phosphirene relative to its isomers. While unsubstituted 1H-phosphirene (12H) is the least stable C2H3P isomer, 1-fluoro-1H-phosphirene (12F) is calculated to be the global minimum of the C2H2FP potential energy surface; 1-chloro-1H-phosphirene (12Cl) is the third most stable of the six C2H2ClP isomers calculated. The remarkable stability of 12F is attributable to the particular strength of the P - F bond.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250425
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    Stereoselektivität von Photocycloadditionen, 5[1] Photoreaktionen zwischen 2-Cyclopenten-1-on und Enolethern (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 933-940 
    Details
    ISSN: 0009-2940
    Keywords: [2 + 2] Photocycloaddition ; Selectivity, stereo-, regio- ; 1,4-Biradicals ; INADEQUATE ; Calculations, AM1, FINITE ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselectivity in Photocycloaddition Reactions, 5[1]. - Photoreaction of 2-Cyclopenten-1-one with Enol EthersThe regio- and stereoselectivity of [2 + 2] photocycloaddition reactions between 2-cyclopenten-1-one (1) and the electron-rich alkenes: ethyl, isopropyl, and phenyl vinyl ether (2-4) as well as 2,3-dihydrofuran (10) were examined. In all cases the annulated cyclobutene derivatives 5-7 and 11 were isolated in yields between 70 and 99%. The regioisomeric HT/HH products were formed in a ratio of 3:1 to 4:1. For the determination of the product stereochemistry, INADEQUATE and 1H,1-decoupling experiments were performed. Computer-assisted investigations on the molecular geometry and 1H,1H-coupling constants were performed by using semiempirical methods (AM1, FINITE). The HT regioisomers were formed with moderate endo diastereoselectivity, whereas in the case of the HH regioisomers both diastereomers (exo/endo) were formed in equal amounts. Photoreaction with 2,3-dihydrofuran (10) led to almost exclusive formation of exo-diastereomeric HH and HT regioisomers 11. The observed stereoselectivity is rationalized by the optimal geometry of the intermediate triplet 1,4-biradicals during intersystem crossing.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250427
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    Synthese und Kristallstrukturen von Carbonyleisen- und Cyclopentadienyleisen-Zweikernkomplexen des 2,3-Diethyl-1,4-dihydro-1,4-dimethyl-1,4-diboranaphthalinsHerrn Professor Wolfgang Beck zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 987-991 
    Details
    ISSN: 0009-2940
    Keywords: 1,4-Diboranaphthalenes ; Iron complexes ; Triple-decker complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Crystal Structures of Carbonyliron and Cyclopentadienyliron Dinuclear Complexes of 2,3-Diethyl-1,4-dihydro-1,4-dimethyl-1,4-diboranaphthalene*Reactions of the 1,4-Diboranaphthalene derivative 1a with (CO)3Fe(C8H14)2 lead to the orange anti dinuclear complex [(CO)3Fe(η6, η4-1a)Fe(CO)3] (4a) and to the cherry-red syn complex [(CO)3Fe(η4, η61a)Fe(CO)2] (5a). The X-ray structure of 5a reveals an Fe - Fe interaction (2.98 Å), 1a reacts with [(C5H5)Fe(C8H12)]2Zn to give the 30-VE triple-decker 7a, in which the diene of the benzo ring can be complexed with a Fe(CO)3 moiety to yield the trinuclear complex 9a.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250502
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    Metallkomplexe in Anorganischen Matrices, 8[1] Chromtricarbonyl-Komplexe von Benzoylacetonat-substituierten Titan-, Zirkonium- und Aluminium-AlkoxidenHerrn Professor Wolfgang Beck zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 999-1003 
    Details
    ISSN: 0009-2940
    Keywords: β-Diketonates ; Metal alkoxides ; Sol-gel chemistry ; π-Arene complexes ; Chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes in Inorganic Matrices, 8[1]. - Chromium Tricarbonyl Complexes of Benzoylacetonate-Substituted Titanium-, Zirconium-, and Aluminium Alkoxides*Benzoylacetone (bzac-H) reacts with one equivalent of Al(OtBu)3 or Zr(OPr)4 to give the mono-substituted compounds (bzac)Al(OtBu)2 (1b) and (bzac)Zr(OPr)3 (1a), while with one equivalent of Ti(OtBu)4 or Zr(OtBu)4 the bis-substituted derivatives (bzac)2Ti(OtBu)2 (3c) and (bzac)2Zr(OtBu)2 (3d) are obtained. Upon heating in dibutyl ether, 1b disproportionates into (bzac)2Al(OtBu) (3b) and Al(OtBu)3. Thermal reaction of 1a, 3b, and 3c with Cr(CO)6 leads to metal complexes having a Cr(CO)3 moiety π-bonded to the phenyl group of the benzoylacetonate ligand.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250504
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    Bis(cyclopentadienyl)methan-verbrückte Zweikernkomplexe, V. Heteronukleare Co/Rh-, Co/Ir-, Rh/Ir- und Ti/Ir-Komplexe mit dem Bis(cyclopentadienyl)methan-Dianion als BrückenligandenHerrn Professor Wolfgang Beck zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1017-1022 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienyl anion, substituted ; Cobalt complexes ; Rhodium complexes ; Iridium complexes ; Bis(cyclopentadienyl)methane dianion as bridging ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes, V[1]. - Heteronuclear Co/Rh-, Co/Ir-, Rh/Ir-, and Ti/Ir Complexes with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand*The lithium and sodium salts of the [C5H5CH2C5H4]- anion, 1 and 2, react with [Co(CO)4I], [Rh(CO)2Cl]2, and [Ir(CO)3Cl]n to give predominantly the mononuclear complexes [(C5H5-CH2C5H4)M(CO)2] (3, 5, 7) together with small amounts of the dinuclear compounds [CH2(C5H4)2][M(CO)2]2 (4, 6, 8). The 1H- and 13C-NMR spectra of 3, 5, and 7 prove that the CH2C5H5 substituent is linked to the π-bonded ring in two isomeric forms. Metalation of 5 and 7 with nBuLi affords the lithiated derivatives 9 and 10 from which on reaction with [Co(CO)4I], [Rh(CO)2Cl]2, and [C5H5TiCl3] the heteronuclear complexes [CH2(C5H4)2][M(CO)2][M′(CO)2] (11-13) and [CH2(C5H4)2]-[Ir(CO)2][C5H5TiCl2] (17) are obtained. Photolysis of 11 and 12 leads almost quantitatively to the formation of the CO-bridged compounds [CH2(C5H4)2][M(CO)(μ-CO)M′(CO)] (14, 15). According to an X-ray crystal structure analysis the Co/Rh complex 14 is isostructural to [CH2(C5H4)2][Rh2(CO)2(μ-CO)] (16).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250507
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    Alkoxygermanate(II), -stannate(II) und -plumbate(II) zweiwertiger Metall-Ionen, II. Verbindungen des Formeltyps M2El2(OtBu)8 (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1033-1042 
    Details
    ISSN: 0009-2940
    Keywords: Germanium compounds ; Tin compounds ; Lead compounds ; Transition-metal complexes ; Paramagnetism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkoxygermanates(II), -stannates(II), and -plumbates(II) of Divalent Metal Ions, II[1]. - Compounds of the Formula M2El2(OtBu)8By simple salt-exchange processes the starting materials Na2El2(OtBu)6 (El = Ge, Sn, Pb) can be transformed to germanates, stannates and plumbates of divalent magnesium and divalent transition metals. Two types of compounds are formed in these reactions: MEl2(OtBu)6 [El = Ge, M = Mg (1A), Cr (1B), Mn (1C), Zn (1F); El = Pb, M = Mn (3C), M = Zn (3F)] and M2El2(OtBu)8 [El = Ge, M = Co (1d), Ni (1e); El = Sn, M = Mg (2a), Cr (2b), Mn (2c), Co (2d), Ni (2e); El = Pb, M = Co (3d)]. Single-crystal X-ray diffraction studies have been performed on 1C, 1d, 2a, 2b, 2c, 2d, and 2e, and the structures have been solved. In 1C the Mn atom occupies the center of an elongated O6 octahedron, the germanium(II) atoms displaying pyramidal coordination by three oxygen atoms. The central molecular cage can be described as two MnO3Ge trigonal bipyramids sharing the common central Mn atom and being wrapped by tert-butyl groups linked to the oxygen atoms. The other compounds of the MEl2(OtBu)6 formula seem to be isostructural with the exception of 3F, which displays a 1H-NMR spectrum which is not compatible with this structure. All X-ray structures of the compounds M2El2(OtBu)8 show the same feature: to a central M2(OtBu)2 four-membered ring are spirocyclically connected two M(OtBu)2El rings through the common metal atoms M. The structure is completed by the coordination of an exocyclic tert-butoxy group to the terminal El atoms. The metal atoms M are therefore quasi tetrahedrally coordinated while the Ge and Sn atoms are in pyramidal threefold oxygen atom environments. All molecules display an El⃛M⃛M⃛El one-dimensional arrangement. From susceptibility measurements it is apparent, that in the compounds MEl2(OtBu)6 and M2El2(OtBu)8 the transition metal atoms are in high-spin configurations, which is also supported by the UV spectra. Analysis of the structural data of the series 2a-2e reveal important contributions of the electronic environments of the transition metal atoms to the M⃛M and M⃛Sn distances. A qualitative MO description is used to explain these features. Again it has been shown that the, „geometrical softness“ of Ge(OtBu)3 and Pb(OtBu)3 is greater than of Sn(OtBu)3, as the former two can accomodate Cr2+ and Mn2+ in a sixfold coordination site by two units, while Sn(OtBu)3 coordinates Cr2+ and Mn2+ with only two alkoxy groups. When 1C and 2d are allowed to react with nonacarbonyldiiron Mn-Ge2(OtBu)6 · 2 Fe(CO)4 (4) and Co2Sn2(OtBu)8 · 2 Fe(CO)4 (5), respectively, are formed. Compound 4 displays presumably five metal atoms in a linear arrangement while 5 has six metallic elements arranged in one dimension. The latter fact has been unambigously proved by an X-ray structure determination.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250509
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    Enantioselektive Katalyse, VIII. Neue 1,2-Bisphosphanliganden mit vier stereogenen Zentren und zusätzlichen Methoxygruppen für die asymmetrische katalytische HydrierungHerrn Professor Wolfgang Beck zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1061-1072 
    Details
    ISSN: 0009-2940
    Keywords: 3,4-Bis(phosphanyl)pyrrolidines ; Palladium complexes ; Rhodium complexes ; Asymmetric hydrogenation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantioselective Catalysis, VIII[1]. - New 1,2-Bisphosphane Ligands with Four Stereogenic Centers and Additional Methoxy Groups for Asymmetric Catalytic Hydrogenation*The synthesis of N-acyl derivatives of all possible diastereomers of [P(R,S), 3R, 4R,P′(R,S)]-3,4-bis[(benzyl)phenylphosphanyl]-pyrrolidine and [P(R,S), 3R, 4R,P′(R,S)]-3,4-bis[(2-methoxybenzyl)phenylphosphanyl]pyrrolidine in optical pure form is described. Palladium and rhodium complexes with these ligands were prepared. The enantioselective hydrogenation of acetamidocinnamic acid with these rhodium complexes was studied at H2 pressures between 1 and 75 bar. There is only a small influence of the 2-methoxy group in the ligand on the catalytic hydrogenation when compared with the respective unsubstituted diastereomer. The structure of {[PR,3R, 4R,P′R)-1-(tert-butoxycarbonyl)-3,4-bis[(2-methoxybenzyl)phenylphosphanyl]pyrrolidine-P,P′}diiodopalladium was determined by X-ray diffraction.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250513
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    Übergangsmetallkomplexe von Diazenen, XXX. Zur Photoreaktion von Octacarbonyl-dimetallaheterocyclen mit Bis(phosphanen)Herrn Professor Dr. Wolfgang Beck zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1083-1086 
    Details
    ISSN: 0009-2940
    Keywords: Dichromium carbonyls ; Diazirine complexes ; Dimetallaheterocycles ; Photosubstitution ; Bis(phosphanes) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition Metal Complexes of Diazenes, XXX[1]. - On the Photoreaction of Octacarbonyl Dimetallaheterocycles with Bis(phosphanes)*Irradiation of (CO)4Cr(μ-pmd)2Cr(CO)4 (1) (pmd = 3,3-penta-methylenediazirine) in the presence of bis(dimethylphosphanyl)methane (dppm) affords (CO)3(μ-pmd)2(μ-dppm)Cr(CO)3 (2b) and (CO)4Cr(μ-pmd)(μ-dppm)Cr(CO)4 (3b) which both contain boat-like dimetallaheterocyclic rings as indicated by X-ray analysis. Contrary to that, in the presence of cis-1,2-bis(diphenylphosphanyl)ethene the reaction affords the known Cr(CO)4(cdpe) (4c) by complete cleavage of the dimetalla-heterocycle.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250516
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    Isocyanid- und Heteroallen-verbrückte Metallkomplexe, X. Protonierung und Alkylierung von (μ-Acylisocyanid)- und (μ-Iminoacylisocyanid)dieisen-Komplexen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1101-1105 
    Details
    ISSN: 0009-2940
    Keywords: Iron complexes, dinuclear ; Bridging functional isocyanides ; N-Protonation (alkylation) ; μ-Aminocarbyne ; μ-2-Azaallyl vs. μ-2-azaallenium ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isocyanide- and Heteroallene-Bridged Metal Complexes, X[1,2]. - Protonation and Alkylation of (μ-Acylisocyanide)- and (μ-Iminoacylisocyanide)diiron ComplexesProtonation of the acyl isocyanide-bridged diiron complexes cis-[Fe2Cp2(CO)3(μ-CNCOR)] [R = Ph (1a); C6H4NO2-(4) (1b)] with HBF4 or HPF6 occurs at the isocyano nitrogen to give the cationic μ-aminocarbyne complexes 2a and 2b, respectively. In contrast, the μ-iminoacyl isocyanide complex 3 is both protonated and alkylated at the imino nitrogen. According to an X-ray structure analysis of 4a, the resulting ligand systems in cis-[Fe2Cp2(CO)3{μ-CNC(Ph)N(Ph)R}]+BF4+ [R = H (4a); Et (4b)] are best described as hybrids of μ-2-azaallylidene-and μ-2-azaallenylidene-type resonance structures.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250519
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    Triazolines, XXXI[1] Reaction of 5-Amino-4,5-dihydro-4-methylene-1H-1,2,3-triazoles with Substituted Thiazolium-4-olates (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 883-887 
    Details
    ISSN: 0009-2940
    Keywords: v-Triazolines ; Thiazolium-4-olates ; 2-Pyridinones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cycloaddition reaction of 5-amino-v-triazolines 2 with thiazolium-4-olates 1 affords two isomeric cycloadducts 3 and 4. A synthetic utilization has been achieved by their desulfuration: The cycloadducts 3 and 4 are catalytically transformed with Raney nickel to pyridinones 5. The acid-catalized rearrangement of 3 and 4 affords the 8-thia-6-azabicyclo[3.2.1]-octane derivatives 6.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250419
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    4,4′-Distyrylazobenzol als Mesogen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 893-897 
    Details
    ISSN: 0009-2940
    Keywords: 4,4′-Distyrylazobenzenes, alkoxy- ; Siegrist Reaction ; Liquid crystals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4,4′-Distyrylazobenzene as MesogenFrom 3,4-dihydroxybenzaldehyde (1) the tetraalkoxy-substituted 4,4′-distyrylazobenzenes (E,E,E)-5a - c are synthesized. A similar reaction sequence leads from ethyl 3,4,5-trihydroxy-benzoate (6) to the hexaalkoxy-substituted 4,4′-distyrylazobenzenes (E,E,E)-11 b, c. With the exception of 5a all products show thermotropic LC properties. Smectic phases have been characterized by polarizing microscopy and by differential scanning calorimetry.
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    URL: http://dx.doi.org/10.1002/cber.19921250421
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    Alkyleisen- und Alkylcobalt-Reagenzien, VI[1] Hohe Überlegenheit der Reagenzien Me4CoLi2 und Me4FeLi2 im Vergleich zu Me2CuLi und Me4MnLi2 bei Kreuzkupplungen mit Vinylbromiden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 913-921 
    Details
    ISSN: 0009-2940
    Keywords: Organocobalt complexes ; Organoiron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkyliron and Alkylcobalt Reagents, VI[1]. - High Superiority of Me4CoLi2 and Me4FeLi2 in Comparison to Me2CuLi and Me4MnLi2 in Cross Coupling Reactions with Vinyl BromidesThe complexes Me4MLi2 (M = Co, Fe, Mn) and Me2CuLi (prepared in situ, but well-known in isolated form) were treated with a series of vinyl bromides. In nearly all cases Me4CoLi2 and Me4FeLi2 proved to be by far the best methylating reagents (high yields, reaction at - 78°C, short reaction time, no excess of the reagent necessary). These reagents will tolerate a hydroxy or cyano group in the substrate, whereas the classical reagent for methylation of vinylbromides, Me2CuLi, is strongly inhibited by these groups. With the methylation of hydroxyvinyl bromides a new method was found for the synthesis of allyl alcohols.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250424
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    Synthese und Eigenschaften von σ-verbrückten Anthracen-Viologenen[1] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 941-950 
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    ISSN: 0009-2940
    Keywords: Donor-acceptor compounds ; Fluorescence ; Electrochemistry ; Viologens ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Properties of of σ-Bridged Anthracene-Viologens[1]The synthesis of the donor-acceptor compounds 2, 7, and 12 where the anthracene donor and the viologen acceptor are linked by a saturated bridge (polymethylene or the bicyclo[2.2.2]octanyl moiety) is described. While the preparation of 2a-c is straightforward, new procedures for the synthesis of the bicyclo compounds 7 and 12 had to be developed. Unexpectedly, the viologens 13d, e could be obtained by direct nucleophilic substitution of the corresponding tertiary and neopentyl-type alkyl tosylates with 4,4′-bipyridine. By comparison of the emission spectra of the compounds 2a and 12a, b the strong fluorescence quenching indicates an electron transfer from the donor to the acceptor.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250428
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    Synthesis and X-Ray Diffraction Analysis of Bis(phenylsulphonyl)semibullvalenes. Lifting of the Degeneracy of Semibullvalenes in the Crystal Lattice[1] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 955-968 
    Details
    ISSN: 0009-2940
    Keywords: Semibullvalenes ; [n.3.3] Propellanes, derivatives of ; Vinyl sulphides and sulphones ; Bromination, allylic ; Debromination ; Zinc-copper couple ; Cope rearrangement in the solid state ; Valence tautomers, non-equivalent ; Equilibrium constants from atomic distances ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bicyclo[3.3.0]octanediones 4 and 9a, b and the [n.3.3]-propellanediones 9c, d, f, h react with thiophenol in the presence of titanium(IV) chloride and triethylamine to afford high yields of the vinyl sulphides 5 and mixtures of the vinyl sulphides 10/11. Sodium perborate oxidizes the vinyl sulphides 5 and 10/11 to the corresponding vinyl sulphones 6 and 12/13. N-Bromosuccinimide converts 6 into the dibromodisulfones 7. The exo,exo configuration of 7b is established by X-ray crystallography. The mixtures of disulphones 12/13 are brominated by N-bromosuccinimide to yield complex mixtures of uncharacterized dibromodisulphones 14. Debromination of the dibromodisulphones 7, and the mixtures of 14 as well, by the zinc-copper couple results in the formation of crystalline semibullvalenes 8 and 15 in moderate to high yields. - X-ray diffraction analyses of 8a, b and 15a-d reveal large variations of the apparent atomic distances in the cyclopropane rings (C2-C8) and at the open ends of the molecules (C4…C6). This result is interpreted in terms of equilibrating, non-degenerate valence tautomers resulting in averaged atomic distances. The equilibrium constants are calculated from the atomic distances on the basis of a limiting value of 157.8 pm for the C2-C8 bonds of the non-rearranging valence tautomers. The results are compared to those obtained from X-ray diffraction analyses of other substituted semibullvalenes. The lifting of the degeneracy of semibullvalenes in the solid state is attributed to subtle intermolecular interactions.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250430
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    Paterno-Büchi Reaction of 2-Morpholinoacrylonitrile with Benzil (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 983-984 
    Details
    ISSN: 0009-2940
    Keywords: Benzil, lowest triplet state of ; [2 + 2] Addition, stepwise ; Oxetanes ; Captodative substitution ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the lowest excited triplet state, benzil (1) adds highly regio- and stereoselectively to the olefin 2-morpholinoacrylonitrile (2) to form solely the oxetane 5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250433
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  • 164
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    Synthesis and Reactivity of Mixed Arene Halides of Niobium(I). Crystal and Molecular Structure of Nbmes2 and [Nbmes2(CO)][Nb2(μ-I)3(CO)8] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1005-1010 
    Details
    ISSN: 0009-2940
    Keywords: Bis-arene complexes ; Niobium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(mesitylen)niobium(0), Nbmes2, prepared via the NbCl5/Al/AlCl3/mes system by exaustive reduction in the presence of 1,2-dimethoxyethane or tetrahydrofuran as previously reported, has been studied by X-ray diffraction methods. The sandwich molecule has parallel, substantially planar, aromatic rings, in an eclipsed conformation. Nbmes2 is oxidized to Nbmes2X by reaction with 1,1-dimethyl-4,4′-bipyridinium halides [methylviologen halides, mvX2 (X = Cl, I)]. The reaction of both halo compounds with CO yielded the niobium(I) derivatives [Nbmes2(CO)] [Nb2(μ-X)3(CO)8]. In the case of X = I an IR study at low temperature has shown the presence of intermediate carbonyl compounds, presumably Nbmes2I(CO) and [Nbmes2(CO)]+. The ionic iodide derivative was shown by X-ray diffraction methods to consist of discrete [Nbmes2(CO)]+ cations and [Nb2(μ-I)3(CO)8]- anions. The two mesitylene groups in the cation are bent and in an eclipsed conformation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250505
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  • 165
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    Dithiocarbonsäuren und Derivate aus Carbonsäureestern und Lactonen mit dem Organoborsulfid-Reagenz (9-BBN)2S (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1023-1032 
    Details
    ISSN: 0009-2940
    Keywords: (9-BBN)2S, reagent ; OC-Sulfoborations ; 1,2-Eliminations, of R2BOR′, (R2B)2O ; Dithiocarboxylic 1,5-cyclooctanediylboryl esters ; Dithiocarboxylic acids ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dithiocarboxylic Acids and Derivatives from Carboxylic Esters and Lactones with the Organoboron Sulfide Reagent (9-BBN)2S[1]Bis(1,5-cyclooctanediylboryl) sulfide (1) reacts with carboxylic esters to give the dithiocarboxylic 1,5-cyclooctanediylboryl esters 2a-f in high yields (2a: X-ray crystal structure analysis). Methanolysis of 2a-f leads to the dithiocarboxylic acids 5a-f, which form the corresponding piperidinium salts in the presence of piperidine. When cyclic esters (γ-, δ-lactones) are allowed to react with 1, the boryloxy-substituted dithiocarboxylic 1,5-cyclooctanediylboryl esters 3a-c are obtained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250508
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  • 166
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    Bis(methylene)phosphorane and Related Compounds: Electrocyclization to Ring Systems (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1319-1323 
    Details
    ISSN: 0009-2940
    Keywords: Bis-ylenephosphoranes, cyclization of ; Calculations, ab initio, MCSCF, SCF ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the bais of ab initio calculations of double-ζ quality at a SCF and MCSCF level, bonding in bis-ylenephosphoranes is compared with the one in phosphoranes. The investigations include the series H3PX, HPX2, HPX (X = CH2, NH, O, SiH2, PH, S). The bis-ylenephosphorane formation becomes more favorable with increasing electronegativity of X. An extreme case is the electropositive group X = SiH2. The resulting π-system suffers from the Jahn-Teller distortion, causing reduction from C2v to lower C2 symmetry in the corresponding bis-ylenephosphorane. Energetically, the corresponding ring systems are more stable than their bis-ylenephoshorane counterparts (for X = CH2 and PH). The electronic hypersurface of the hitherto unknown bis(phosphinylidene)phosphorane is explored in detail and compared in regard to bonding with its analog bis(methylene)phosphorane. For both cases π-push-pull substitution is important for stabilization of the planar allylic geometry.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250604
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  • 167
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    Addition von Silylenen an Iminoborane (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1073-1078 
    Details
    ISSN: 0009-2940
    Keywords: Iminoboranes ; Silylenes ; Azasilaboriridin ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of Silylenes to Iminoboranes[1]Photolytically generated silylenes SiMe2 and SiMes2 are treated with iminoboranes XB≡NtBu [X = tBu, Me3Si(tBu)N, iPr2N: 1a-c]. The products from SiMe2 and 1a are the four-and six-membered rings [-B(tBu)=N(tBu)-SiMe2-SiMe2-] (3a) and [-B(tBu)=N(tBu)—B(tBu)N(tBu)-SiMe2-SiMe2-] (4a), depending on the conditions of the photolysis. SiMe2 reacts with 1b to give the six-membered ring [-BX=N(tBu)-SiMe2-BX=N(tBu)-SiMe2-] (4b). From SiMes2 and 1a,c the three-membered rings [-BX=N(tBu)-SiMes2-] are formed (2a: space group Pbca; 2c: space group P1): SiMes2 reacts with 1b to yield the unexpected four-membered BNSiN ring [B(Mes)N(tBu)-Si(Mes)(SiMe3)-N(tBu)] (5: space group P1).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250514
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  • 168
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    Isocyanid- und Heteroallen-verbrückte Metallkomplexe, VIII. Dieisenkomplexe mit Acylisocyanid- und Iminoacylisocyanid-Brückenliganden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1087-1092 
    Details
    ISSN: 0009-2940
    Keywords: Isocyanides, functional ; Isocyanide-bridged metal complexes ; Iron complexes, dinuclear ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isocyanide- and Heteroallene-Bridged Metal Complexes, VIII[1,2]. - Diiron Complexes with Bridging Acyl Isocyanide and Iminoacyl Isocyanide LigandsAcylation (aroylation, carbamoylation, imino acylation) of the terminal cyano ligand in Na[Fe2(CN)Cp2(CO)3] (1) leads to the acyl isocyanide (aroyl, carbamoyl, iminoacyl isocyanide)-bridged neutral complexes [Fe2Cp2{μ-CNC( = O)R}(CO)3] (2a-i) and [Fe2Cp2{μ-CNC( = NPh)Ph}(CO)3] (3). An X-ray structure analysis has been carried out of the pentafluorobenzoyl isocyanide complex 2 f, important results of which are the cis configuration of the complex, the 163.7° puckering of the central Fe2(μ-C)2 rhomboid, short [1.892(5), 1.911(5) Å] Fe-μ-C distances to the acyl isocyanide ligand, the nonplanarity of the latter and the 132° bend at the isocyano nitrogen. The contribution of a μ2-2-azaallenylidene form is assumed to explain the bonding.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250517
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  • 169
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    Isocyanid- und Heteroallen-verbrückte Metallkomplexe, IX. Di- und Trieisenkomplexe mit funktionellen Isocyanidbrücken (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1093-1100 
    Details
    ISSN: 0009-2940
    Keywords: Isocyanide dichlorides, functional ; (Lewis)Basic metals ; (Three component)Oxidative additions ; Iron complexes, di- and trinuclear ; Isocyanide bridges, functional ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isocyanide- and Heteroallene-Bridged Metal Complexes, IX[1,2]. - Di- and Triiron Complexes with Functional Bridging IsocyanidesThe reactions of ten mainly functional isocyanide dichlorides RN = CCl2 with Na[FeCp(CO)2] in tetrahydrofuran give mono-isocyanide derivatives [Fe2(Cp)2(CO)3CNR] (1 a-g) of [Fe-Cp(CO)2]2 in which the isocyanide occupies a bridging position. In three cases also minor amounts of diisocyanide complexes [FeCp(μ-CNR)CO]2 (2c, 2e, 8) have been isolated. The chlorocarbonyl-substituted aryl isocyanide dichlorides and pentafluorophenyl isocyanide dichloride in addition suffer (CO)Cl/ and F/ metal exchange, respectively, with formation of μ3-isocyanide-bridged triiron complexes (4 a-c, 7) via the intermediates 5 and 6, 7 has been studied by X-ray analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250518
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  • 170
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    Monomere und dimere 1,3-Diaza-2-phosphaallyllithium-Komplexe: Strukturen und ambidente ReaktivitätHerrn Professor Hans-Friedrich Grützmacher zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1119-1124 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Diaza-2-phosphaallyllithium ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomer and Dimer 1,3-Diaza-2-phosphaallyllithium Complexes: Structures and Ambident Reactivity*Metallation of the NH-functional amino(imino)phosphanes Mes*NPNHR (R = CPh3, Ad, tBu) 1a-c yields the 1,3-diaza-2-phosphaallyllithium compounds 2a-c. The crystal structure shows an ether-stabilized monomer of 2a and a solvent-free dimer with an eight-membered ring in the case of 2b, c. The reaction of 2b with chlorodiphenylphosphane yields, dependent on the reaction conditions, (phosphanylamino)iminophosphane 3 or bis(imino)phosphanylphosphorane 4. The structural and reactivity is discussed on the basis of ab initio calculations.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250522
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  • 171
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    Organische Synthesen mit Übergangsmetall-Komplexen, 58. Heptafulvenylcarben-Komplexe von Chrom und Wolfram. - Azaspiro[4]-Anellierung an 1-Metalla-1,3-diene mit Isocyaniden; Liganden-Abspaltung mit Pyridin oder durch ThermolyseHerrn Professor Wolfgang Beck zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1141-1145 
    Details
    ISSN: 0009-2940
    Keywords: Heptafulven-8-ylcarbene complexes of chromium and tungsten ; (Tropyliummethyl)carbene complexes of chromium and tungsten ; Pyrrolylidene complexes, by electrocyclisation of C-alkenylketenimine complexes ; 1-Metalla-1,3-diene, azaspiro[4] anellation to ; Disengagement of ligands with pyridine ; 1-Amino-2-alkoxyazulenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 58[1]. - Heptafulvenylcarbene Complexes of Chromium and Tungsten. - Azaspiro[4] Anellation to 1-Metalla-1,3-dienes with Isocyanides; Displacement of Ligands by Pyridine or by Thermolysis*(Cycloheptatrien-1-ylmethyl)carbene complexes LnM = C(OEt)CH2-c-C7H7 3 [LnM = Cr(CO)5 (a), W(CO)5 (b)] are transformed into heptafulven-8-ylcarbene complexes LnM = C(OEt)CH = c-C7H7 5 in two steps. The first step involves the formation of (tropyliummethyl)carbene complexes [LnM = C(OEt)CH2-c-C7H6]+ [BF4]- 4 by a hydride abstraction from the cycloheptatriene ring of 3 with [Ph3C]+ [BF4]- (4a, 4b: 70%). 4 is deprotonated with Et3N to give 5 (5a: 89%; 5b: 92%). 5 adds one equivalent of cyclohexyl isocyanide (6) to the LnM = C - C = C unit via the intermediate ketenimine complexes LnM[c-C6H11N = C = C(OEt) - CH = c-C7H6] 7, which cyclize spontaneously and form the (thermolabile) azaspiro[4.6]undecatetraene complexes 8 (8a: 91%; 8b: 93%). The reaction of 8a, b with pyridine leads to the disengagement of a pyrrole 10 in almost quantitative yields. Thermolysis of 8a, b in the absence of pyridine gives an azulene 12.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250525
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  • 172
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    Cycloaddition Products from (1-Diazo-2-oxoalkyl)silanes and Cyclopropenes. A Silatropic 2,3-Diazabicyclo[3.1.0]hex-3-ene/1,4-Dihydropyridazine EquilibriumDedicated to Professor Hans-Friedrich Grützmacher on the occasion of his 60th birthday. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1227-1234 
    Details
    ISSN: 0009-2940
    Keywords: (1-Diazo-2-oxoalkyl)silanes ; Cyclopropenes ; Cycloaddition ; Silyl shift ; Homopyrazole ; 1,4-Dihydropyridazine isomerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (1-Diazo-2-oxoalkyl)silanes 1a-h react with cyclopropene 4 to form 2-silyl-2,3-diazabicyclo[3.1.0]hex-3-enes 5 and/or 1-silyll-1,4-dihydropyridazines 6. In most cases, a temperature- and solvent-dependent equilibrium 5 ⇄ 6 maintained by an N →N′ silyl shift exists in solution. With cyclopropene 10, only the 1-silyl-1,4-dihydropyridazines 11 are obtained. None of the 1:1 adducts corresponds to the product expected from a [3 + 2] cycloaddition reaction between the components. Evidence is presented that 1-diazo-2-siloxy-1-alkenes 2 are initially formed from 1 by a 1,3-(C → O) silyl shift and are then trapped by the cyclopropene in a 1,3-dipolar cycloaddition reaction.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250532
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  • 173
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    (Tetracyannaphthalocyaninato)eisen(II) mit Isocyaniden als axialen LigandenHerrn Professor Dr. Horst Prinzbach zum 60. Geburtstag gewidmet. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1243-1247 
    Details
    ISSN: 0009-2940
    Keywords: (Tetracyanonaphthalocyaninato)iron(II) ; Isocyanide complexes ; Semiconductors ; organic ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Tetracyanonaphthalocyaninato)iron(II) with Isocyanides as Axial Ligands(Tetracyanonaphthalocyaninato)iron(II) [(CN)4-2,3-NcFe; 6] is obtained by treating 2,3,6-tricyanonaphthalene (5) with iron(II) acetate. Compound 5 is synthesized according to the route given in Scheme 1. The mononuclear bisaxial isocyanide complexes (CN)4-2,3-NcFeL2 7-9 with L = tBuNC, cHxNC and AdNC as well as the bridged complex [(CN)4-2,3-NcFe(dib)]n (10) are formed as stable compounds by treating 6 with the neat ligands L. The spectroscopic properties of the complexes are described and compared with the analogous compounds (CN)4PcFeL2, 2,3-NcFeL2, 1,2-NcFeL2, and with PcFeL2. The bridged complex [(CN)4-2,3-NcFe(dib)]n (10) exhibits only poor semiconducting properties as compared to [2,3-NcFe(dib)]n. The oligomer 10 can be doped with iodine, and the resulting product [(CN)4-2,3-NcFe(dib)I1.4]n shows a powder conductivity s̰RT = 2 × 10-5 S/cm at room temperature.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250534
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  • 174
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    Erste röntgenographische Charakterisierung N-lithiierter 4-Alkyliden-1,4-dihydropyridine des Typs [{4-(CH3CR)C5H4N}Li(TMEDA)]2: Vergleich von Kristall- und MNDO-Strukturdaten sowie Untersuchungen zur Lithium-Koordination in Lösung (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1267-1271 
    Details
    ISSN: 0009-2940
    Keywords: 4-Alkylpyridines, lithiated ; Lithium coordination in solution ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The First X-ray Structures of N-Lithiated 4-Alkylidene-1,4-dihydropyridines [{4-(CH3CR)C5H4N}Li(TMEDA)]2: Comparison of the X-ray and MNDO Geometries and Investigation of Lithium Coordination in SolutionThe 4-ethyl- and -isopropylpyridines 5a and b were transformed into the lithiated compounds [{4-(CH3CH)C5H4N}-Li(TMEDA)]2 (6a) and [{4-(CH3CCH3)C5H4N}Li(TMEDA)]2 (6b) by reaction with LDA and in the presence of TMEDA. These compounds were recrystallized from a toluene/hexane solution to obtain suitable crystals for X-ray investigations. Both structures are dimeric containing nonstoichiometric amounts of toluene in the crystals. The structural parameters of the heterocyclic moieties of 6a or b are typical of N-lithiated 4-alkylidene-1,4-dihydropyridines. MNDO geometries compare quite well with the X-ray structure of 6a. The lithium atom of 6a in solution prefers the same type of coordination as in the crystal: Two-dimensional 6Li,1H-HOESY showed Li contacts only to ortho-hydrogen atoms (Figure 3). 6a and b react differently with chlorotrimethylsilane (8). The variations of the alkylidene moieties of 6a and b, although seemingly small, are decisive: While the α,α-dimethyl compound 6b reacts exclusively as an N nucleophile, the α-methyl compound 6a functions also exclusively as a Cα nucleophile.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250537
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  • 175
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    2-Oxabicyclo[3.2.1]oct-7-yl-Kationen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1295-1296 
    Details
    ISSN: 0009-2940
    Keywords: Wagner-Meerwein rearrangement ; Oxonium ions ; n Participation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Oxabicyclo[3.2.1]oct-7-yl Cations2-Oxabicyclo[3.2.1]octan-7-one (10) was prepared in five steps, starting from 3-cyclopenten-1-ol (5). The tosylhydrazone 11, derived from 10, was photolyzed in 0.5 N NaOD/D2O to give 〉99% of 2-oxabicyclo[3.2.1]octan-exo-7-ol (9) with equal distribution of D at C-1 and C-7. In contrast to the parent 6-bicyclo[3.2.1]octyl cation (1), the oxa analog 14 exhibits the same symmetry as was observed with the 6-oxa-2-norbornyl cation (13). The conformational effects that are evident in 1 are overruled by strong n participation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250541
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    Masthead (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250601
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    The unusual oxidation of a 1,5,2,4-diazadiphosphorinan-6-one with tetrachloro-ortho-benzoquinone (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1325-1332 
    Details
    ISSN: 0009-2940
    Keywords: 1,5,2,4-Diazadiphosphorinan-6-one ; Tetrachloro-ortho-benzoquinone ; Oxidation ; Spirophosphorane ; Spirophosphorate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of 2,4-bis(diethylamino)-1,5-dimethyl-1,5,2,4-diazadiphosphorinan-6-one (1b) with two equivalents of tetrachloro-ortho-benzoquinone (TOB) (2) leads to the cleavage of the original heterocycle and to the formation of a mixture of compounds, including the 1,3,2-diazaphosphetidine 6 (“λ6P-”) and the spirophosphorane 7. Compound 7 exists as two isomers that undergo slow spontaneous transformation in solution to compound 9, containing a six-coordinate phosphorus atom. When the oxidation of 1b is carried out in two stages, with the second equivalent of TOB being added after an interval of four days, the cleavage of the original molecule does not occur, and compound 17, containing a seven-membered ring with two phosphorus atoms of opposite formal charge and different coordination number (“λ4P+,λ6P-”) is formed. The structures of 6, 7, 9, and 17 were established by low-temperature X-ray analysis. Compound 6 displays crystallographic twofold symmetry; the coordination at phosphorus is octahedral, but distorted by the phosphetidine ring. The phosphorus atom in 7 possesses square pyramidal coordination geometry, the pyramid base being defined by the four oxygen atoms. Compound 9 (“λ6P-”) crystallized with two molecules of CDCl3. Compound 17 crystallized as a dichloromethane solvate. Distorted octahedral and tetrahedral geometries were observed for P1 and P2, respectively. The four-membered ring is planar. The bridging hydroquinone ligand displays much wider O-C-C(-O) and C-O-P angles than the chelating hydroquinone.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250605
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    Substituierte 2,5-Dihydro-1,2,5-oxoniadiboratole, cis-1,2-Diborylalkene und 1,2,5-Oxadiborolane - Herstellung und Charakterisierung (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1351-1362 
    Details
    ISSN: 0009-2940
    Keywords: 1,2,5-Oxoniadiboratoles, 2,5-dihydro-, organo-substituted ; 1,2,5-Oxadiborolanes, organo-substituted ; 1,3,2-Diboroxanes, substituted with unsaturated residues ; Boryl-germyl exchange ; cis-1,2-Diborylalkenes, organo-substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted 2,5-Dihydro-1,2,5-oxoniadiboratoles, cis-1,2-Diborylalkenes, and 1,2,5-Oxadiborolanes - Preparation and CharacterizationThe potassium salts (A: R = R′ = Et; B: R2 = C8H14, R′ = Me; C: R2 = C8H14, R′ = Et) react with various electrophiles (H+, R+, Me3ElIV+) to form substituted 1,3,2-diboroxanes (1, iso8b) including 1,2,5-oxadiborolanes (2, 4, 6, 9, 10), dialkylvinylboranes (1'), 2,5-dihydro-1,2,5-oxoniadiboratoles (3, 5) and cis-1,2-diborylalkenes (7, 8). In particular, A-C react with HCl (as Me3NHCl/THF or HCl/Et2O) to give O[B(Et)C(Et) = CHR]2 (1a: R = Me; 1b: R = Et), R2BCR′ = CHEt (1'a: R = R′ = Et; 1'b: R2 = C8H14, R′ = Me; 1'c: R2 = C8H14, R′ = Et) and (2a: R,R′ = Et; 2b: R2 = C8H14, R′ = Me; 2c: R2 = C8H14, R′ = Et). With MeI in THF the cyclic compounds (3a) or (4b/4'b: R = Me; 4c/4'c: R = Et) and with Et3O · BF4 in CH2Cl2 the heterocycle - (5a) and cis-EtOB(C8H14)C(Et) = C(Et)BEt (5c) and/or (6b: R = Me; 6c: R = Et) are obtained. The reactions of A with ClElIVMe3 (ElIV = Si, Ge, Sn) lead to cis-Et2BC(Et) = CB(Et)OE1IVMe3 [ElIV=Si(7a), Ge (8a)] and to cyclic (9a). The salts B and C react with ClElIVMe3 (ElIV = Si, Ge) to form cis-C8H14BC(R) = C(Et)B(Et)OElIVMe3 (ElIV = Si: 7b: R = Me; 7c: R = Et; ElIV = Ge: 8b: R = Me, 8c: R = Et). On heating 8b isomerizes to cis-Me3GeC(Me) = C(Et)B(Et)OBC8H14 (iso8b). From B and C with ClSnMe3 the substituted 1,2,5-oxadiborolanes (10b/10'b: R = Me; 10c: R = Et) are obtained together with (C8H14B)2O.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19921250608
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    Spektroskopischer Nachweis eines Bis(amino)silylens (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1375-1377 
    Details
    ISSN: 0009-2940
    Keywords: Silicon(IV) diazide ; Photolysis ; Matrix isolation ; Silylene, bis(amino)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectroscopic Identification of a Bis(amino)silyleneThe photolysis of the silicon diazide 3a in benzene solution and in an Ar matrix is described. Both irradiations cause the elimination of 3 equivalents of N2. Loss of N2 from 3a in benzene leads to the formation of the analytically investigated product or products 4 of uncertain structure. However, the matrix photolysis of 3a results in a compound which is stable up to 77 K and has been identified as the bis(amino)silylene 2d by comparison of its IR spectra with those of the homologous Sn and Ge compond.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250611
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  • 180
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    Synthesewege zu neuen ionischen Ozoniden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1383-1388 
    Details
    ISSN: 0009-2940
    Keywords: Phase-transfer catalysis ; Ozonides, ionic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic Routes to New Ionic OzonidesNew synthetic routes to tetraorganylammonium ozonides involving exchange reactions with alkali metal ozonides were investigated. The previously reported reaction between tetraalkylammonium hyperoxides R4N+O2- (R = Me, Et) and alkali metal ozonides in liquid ammonia is severely hampered by the difficult synthesis of these hyperoxides; they are unknown for other quaternary ammonium cations. A similar reaction between the easily accessible chlorides of trialkylbenzylammonium ions and KO3 yields mixed ozonides/chlorides due to some solubility of KCl in liquid ammonia. The new compounds BzlMe3N+ (O3-)0.6Cl-0.4 (3), BzlEt3N+ (O3-)0.8Cl0.2- (4) and Bzl(nBu)3N+(O3-)0.5Cl0.5- (5) were prepared by this route. - The by far superior route to new ozonides utilizes macroreticular cation exchange resins in liquid ammonia. Batch equilibration between an excess of the appropriate ionic form of the resin and CsO3 produced Me3PhN+O3- (6), BzlMe3N+O3- (7), Bzl(nBu)3N+O3- (8), and (nPr)4N+ O3- (9) in almost quantitative yield. Compounds 4, 6, and 7 were studied by single-crystal X-ray analysis; the shortening of the ozonide bond length and the widening of the bond angle in comparison to the alkali metal ozonides as well as the possibility of C-H…O hydrogen bonding are discussed. Thermal stabilities were determined by DTA/TG methods, rapid decomposition starts at 59-79°C for 3, 6, and 7 and at 28-56°C for the remaining new ozonides which contain detachable β-H atoms.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250613
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  • 181
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    Hexasilylbenzene, C6(SiH3)6 (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1401-1403 
    Details
    ISSN: 0009-2940
    Keywords: Benzene, hexasilyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound was obtained in a four-step synthesis starting from (4-methoxyphenyl)silane. Owing to the presence of activating p-methoxy groups in the key intermediate hexakis[(4-methoxyphenyl)silyl]benzene (4), the peripheral aryl groups can be cleaved selectively from the silicon atoms with trifluoromethanesulfonic acid, leaving the Si-C bonds to the central benzene ring intact. LiAlH4 reduction of the resulting hexakis[(trifluoromethylsulfonyloxy)silyl]benzene (5) finally leads to crystalline, sublimable, air-stable C6(SiH3)6 (6), m.p. 165°C. In the crystals (triclinic, space group P&1macr;) the structure of the centrosymmetrical molecules approaches very closely point group D3d, as predicted from theoretical considerations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250616
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  • 182
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    Elektroreduktion organischer Verbindungen, 20[ Darstellung von Bicyclo[n.1.0]alkanen durch elektrochemische Reduktion von 1,3-Dibromcycloalkanen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1415-1419 
    Details
    ISSN: 0009-2940
    Keywords: Electrochemical reduction ; Bicyclo[n.1.0]alkanes ; Cycloalkanes, 1,3-dibromo ; Hunsdiecker reaction ; 1,3-Cycloalkanedicarboxylic acids ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Bicyclo[n.1.0]alkanes by Electrochemical Reduction of 1,3-DibromocycloalkanesGood yields of bicyclo[2.1.0]pentane (17) and bicyclo[3.1.0]-hexane (3) are obtained on electroreduction of the corresponding 1,3-dibromocycloalkanes. The results do not depend upon the stereochemistry of the starting material (14 vs. 15 or 11 vs. 12).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250619
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  • 183
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    Wasserstoffübertragungen, 21[1] Pericyclische Wasserstoff-Übertragung von 1,2-Dihydroarenen auf ein Cycloheptin (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1439-1447 
    Details
    ISSN: 0009-2940
    Keywords: Hydrogen transfer, pericyclic ; Aromatization ; Isotope effects ; Ring strain ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrogen Transfer Reactions, 21. - On the Pericyclic Hydrogen Transfer from 1,2-Dihydroarenes to a CycloheptyneThe aromatization of 1,2-dihydroarenes by thiacycloheptyne 1 takes place by a pericyclic process. This mechanism is supported by the dependence of the reactivity on the π system, absence of both substituent and solvent effects, a strong negative entropy of activation, high stereoselectivity of hydrogen abstraction, as well as size and consistency of primary isotope effects and semiempirical calculations of the transition state.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250622
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  • 184
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    Asymmetric induction in reductively initiated [2,3]-Wittig and retro [1,4]-brook rearrangements of secondary carbanions (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1471-1484 
    Details
    ISSN: 0009-2940
    Keywords: Rearrangement, sigmatropic ; Brook rearrangement ; [2,3]-Wittig rearrangement ; Metalation, reductive ; Asymmetric induction ; 1,3-Diol synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of O,S-acetals and the lithium naphthalenide initiated rearrangement reactions thereof are described. O,S-Acetal 8a resulted from trapping of the 1,4-dipole 7 with thiophenol. O,S-Acetals 16a and b were obtained from aldehydes 14a/b by a one-pot reaction with (trimethylsilyl)prenol, (tri-methylsilyl)thiophenol, and trimethylsilyl triflate. Upon reduction with lithium naphthalenide all O,S-acetals delivered α-lithiated ethers. They rearranged either in a [2,3]-Wittig mode furnishing the 1,3-diol derivatives 20a-h/21 with moderate stereoselectivity (syn:anti = 35:65 to 78:22) or underwent retro [1,4]-Brook rearrangements yielding the α-silyl ethers 23i-k/24 with still less stereocontrol (syn:anti = 34:66 to 50:50). The mechanistic implications are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250625
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    Synthesis of new soluble triphenodithiazines and investigation of their donor properties (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1495-1500 
    Details
    ISSN: 0009-2940
    Keywords: Triphenodithiazines ; Organic donor molecules ; Charge-transfer complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of 6 and 7, starting from 3,6-dichloro-2,5-bis(2-thioanisido)-1,4-benzoquinone (4), are reported. The solid-state conformations of 6 and 7 are elucidated by X-ray structure analysis, and the cyclovoltammetric investigation of 6 and 7 in solution shows low and reversible oxidation half-waves for both compounds. The relatively high oxidation potentials of 7 compared to 6 are related to their conformational features. EPR measurements on the radical cations derived from 6 and 7 both suggest a planarized conformation of these species. Oxidation of 6 with strong oxidants leads quantitatively to the quinoid triphenodithiazine 8, whereas the charge-transfer complex formed between 7 and DDQ exhibits semiconducting properties.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250627
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    Masthead (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250701
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  • 187
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    CO2-Aktivierung an Übergangsmetallzentren: Simulation enzymatischer CO2-Fixierungs- und Transferreaktionen durch elektronenreiche (Diazadien)magnesium- und -mangan-Komplexe (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1529-1536 
    Details
    ISSN: 0009-2940
    Keywords: Carbon dioxide fixation ; Metal complexes ; Diazadiene ligands ; Carboxylation ; Enzyme models ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Activation of CO2 at Transition-Metal Centres: Simulation of Enzymatic CO2 Fixation and Transfer Reactions by Electron-Rich (Diazadiene)magnesium and -manganese ComplexesElectron-rich diazadiene complexes of Mg and Mn can be used as model compounds for enzymatic carboxylation reactions e.g. the „dark reaction“ of the photosynthesis or in biotinedependent CO2 conversion reactions. The activity of the complexes to fix and transfer carbon dioxide strongly depends on the nature of the metal (Mg and Mn are active central atoms, other transition metals are inactive), the π aciditiy of the chelate ligand, and the structure of the complexes. The dimeric manganese complex IIa, the structure of which could be determined by X-ray structure analysis, is one of the most active compounds. NMR studies reveal that the CO2 transfer to substrates with active C - H bonds takes place in the coordination sphere of the metal atom. Carrier of activated CO2 is the N - COO group.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250703
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  • 188
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    Metallcarbonyl-Synthesen, XXI. Einfache Synthese eines präparativ nützlichen Alkoxy(carbonyl)metallats (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1795-1799 
    Details
    ISSN: 0009-2940
    Keywords: Carbonyl complexes ; Rhenium complexes ; Alkoxy carbene, structure of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Carbonyl Syntheses, XXI. - Straightforward Synthesis of a Synthetically Useful Alkoxy(carbonyl)metallateAnionic methoxy complexes are formed upon carbonylation of ammonium perrhenate in methanol at 230-240°C. Thus, the dinuclear ionic complex [N(CH3)4][Re2(CO)6(μ-OCH3)3] (2) results in 80% yield at CO pressures of ca. 100 bar, while the trinuclear derivative [N(CH3)4][Re3(CO)9(μ3-OCH3)3(μ3-OCH3)] (3) is due to lower pressure conditions (ca. 50 bar); 2 yields the bis(carbene) complex 4 of formula fac-Re(CO)3L2I upon treatment with a bis(imidazolium) iodide, thus demonstrating that carbonylrhenium chemistry not necessarily depends on the availability of Re2(CO)10.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250803
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    Zur Darstellung von Nonafluorbutansulfonsäureestern (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1763-1767 
    Details
    ISSN: 0009-2940
    Keywords: Nonafluorobutanesulfonic acid, alkyl and silyl esters ; Alkylation ; Silylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Esters of Nonafluorobutanesulfonic AcidA series of new alkyl (2a-e), silyl (6a-1), germyl (7) and stannyl esters (8a, b) of nonafluorobutanesulfonic acid has been prepared by different methods (A-I) e.g. C4F9SO2OR [R = Me,Et, CH2CF3, CH2CCl3, CF3, GeMe3, SnMe3, SnEt3] and C4F9SO2OSiR3 [R = Me, Et, iPr, Bu, H, F, Cl, Ph, Ph2Me, PhMe2, Cl2Me]. These compounds are useful and extremely powerful alkylating or silylating reagents.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250731
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    Polar Effects in Halogen Abstraction Reactions of Alkyl Radicals (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1777-1779 
    Details
    ISSN: 0009-2940
    Keywords: Polar effects ; Radical clock ; Cobaloximes, alkyl ; Radicals, alkyl ; Chlorine abstraction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a series of structurally similar alkyl radicals 1a-c the tertiary 1,1-dimethyl-5-hexenyl radical 1c reacts 30 times faster with carbon tetrachloride than the primary 5-hexenyl radical 1a. The reactivity of the secondary 1-methyl-5-hexenyl radical 1b aligns itself in between the primary and the tertiary radical 1a and 1c. The results indicate that the increasing nucleophilicity of the alkyl radicals is the major factor contributing to the reactivity.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250734
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  • 191
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    Reaktionen koordinierter Liganden, XVIII. Templatsynthesen und Peripheriereaktionen makrocyclischer Multiphosphanliganden mit funktionellen Gruppen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1785-1794 
    Details
    ISSN: 0009-2940
    Keywords: Template synthesis ; Phosphane complexes, macrocyclic, tetradentate ; Periphery reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Coordinated Ligands, XVIII. - Template Syntheses and Periphery Reactions of Macrocyclic Multiphosphane Ligands with Functional GroupsCyclisation of the tridentate phosphanes PhP([CH2]3PRH)2 (R = H, Me) with the divinyl components R′P(CH=CH2)2 [R′ = Ph, NEt2, O(iPr)] within Ni(II) templates affords complexes NiBr2L (3a-f) of functionalised macrocyclic tetraphosphanes (L) in almost quantitative yields. An X-ray structural analysis of the cyano complex [Ni(CN)L]PF6 (5a), obtained by metathetical reactions, reveals a folded 14-membered macrocyclic ligand L. The P atoms occupy axial and equatorial positions within the trigonal-bipyramidal ligand arrangement with an equatorial CN group. By periphery reactions at the P-NEt2 function of the 14-membered ring system P—OH, P—O-, P—Cl, P—OR″ derivatives (R″ = Me, iPr, CH2CH=CH2) are formed. Addition of methyl acrylate to the P—H functions in 3d and 3f leads to macrocyclic diesters 12a, 12b. By cleavage of the P—N bond in 3a with concentrated aqueous HBr a complex of composition 7a · HBr · 3 H2O is obtained. An X-ray structural analysis of the latter shows a P—OH functionalised macrocyclic tetraphosphane occupying the four basal positions within a square pyramidal coordination geometry at Ni(II).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19921250802
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    Derivate des Borols, XVIII. Tricarbonyl[η5-(1-phenylborol)]eisen: Zur Reaktivität der koordinierten Liganden (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1801-1805 
    Details
    ISSN: 0009-2940
    Keywords: (Borole)carbonyliron derivatives, electrophilic substitution, nucleophilic addition, reduction ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of Borole, XVIII. - Tricarbonyl[η5-(1-phenylborole)]iron: Reactivity of the Coordinated LigandsThe borole complex (C4H4BPh)Fe(CO)3 (1) undergoes Friedel-Crafts acetylation (MeCOCl/AlCl3) at the meta-position of the phenyl substituent while the derivatives (C4H4BPh)Fe(CO)2L (3, a: L = NMe3′ b: L = PMe3) are acetylated at the 2-position of the borole ring. Organolithium reagents (LiMe, LiBu) add to 1 at the boron atom below - 50°C while nucleophilic attack at the carbonyl C atom takes place at higher temperature with formation of acyl anions [(C4H4BPh)Fe(CO)2(COR)]- (6a,b-). The Fischer carbene complex (C4H4BPh)Fe(CO)2[C(OMe)Me] (7) is obtained from 6a-/[Me3O]BF4. Complex 1 reacts with LiN(SiMe3)2 to give [(C4H4BPh)Fe(CO)2(CN)]- (8-) and with 5 M NaOH/C6H6/NBu4HSO4 to produce the hydride NBu4-[(C4H4BPh)FeH(CO)2] (NBu4 · 9). A highly reactive dianion [(C4H4BPh)Fe(CO)2]2- (102-) is obtained by deprotonation of 9- or by reduction of 1 or 3a in THF at -70°C. Treatment of 102- with Ph3SnCl gives [(C4H4BPh)Fe(CO)2(SnPh3)]- (11-) which is isolated as NEt4 · 11. Slow reduction of 3a with sodium amalgam in THF at -30°C produces doubly CO-bridged cis-[{(C4H4BPh)Fe(CO)2}2]2- (122-) which is protonated to the μ2-hydrido anion [μ-H-{(C4H4BPh)Fe(CO)2}2]- (13-).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250804
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    Conformation in the Solid State and in Solution of 3,3′(4H,4′H)-Spirobi[2H-1,5-benzodioxepin] (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1837-1841 
    Details
    ISSN: 0009-2940
    Keywords: Circular dichroism ; Spiranes, absolute configuration and conformation of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The “spiro-coplanar” conformation of 6,6′-methoxycarbonyl-3,3′(4H,4′H)-spirobi[2H-1,5-benzodioxepin] (1b) and the 3P configuration of the corresponding menthol ester 1c have been determined from chiroptical data by application of the exciton theory. The solid-state conformation of the central part of the menthol ester molecule is “spiro-coplanar”, too, with nearly D2 symmetry. The menthol moieties have chair conformations, and the absolute configurations at their chiral centers have been assigned using enantiomer-sensitive Bijvoet pairs; they are in agreement with the known absolute configuration of menthol.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250809
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    Carbonyl O-Oxides and Dioxiranes: The Influence of Substituents on Spectroscopic Properties (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1851-1859 
    Details
    ISSN: 0009-2940
    Keywords: Carbonyl oxides ; Quinone oxides ; Dioxiranes ; Substituent effects ; Matrix isolation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triplet 4-oxocyclohexadienylidenes 6, matrix-isolated in Ar/ 2% O2 at 10 K, react with triplet O2 on annealing the matrix. Primary reaction products are quinone oxides 4, which have been characterized by IR and UV/Vis spectrometry. They are very photolabile; long-wavelength irradiation converts them into spiro-dioxiranes 5, which in turn yield lactones 10 upon irradiation with visible light. Experimental data have been obtained for quinone oxides 4a-g; additionally, ground-state properties and UV/Vis absorptions of quinone oxides 4a,b and 4e-1 have been calculated by the MINDO-3/UHF and CNDO/S methods. Since the theoretical and experimental maxima of the π → π* transitions are in good agreement, we conclude that our semiempirical calculations give an adequate picture of quinone oxides 4 which may best be described as dipolar diradicals.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250811
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    Makrobicyclische Endorezeptoren: Synthese, Kristallstruktur und Einschluß organischer Gastmoleküle (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1873-1880 
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    ISSN: 0009-2940
    Keywords: Complex formation ; Endoreceptors ; Macrobicyclic ligands ; Phenanthroline derivatives ; Supramolecular chemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Macrobicyclic Endoreceptors: Synthesis, Crystal Structure, and Inclusion of Organic GuestsThe macrobicyclic ligand 2 is synthesized in a one-step cyclization procedure. According to an X-ray structure analysis three dichloromethane guest molecules are included inside the cavity, whereas water and methanol are found outside the cavity. The rigid endo preorganization of the nitrogen donors allows the complexation of three 2,9-disubstituted 1,10-phenanthrolines inside the cavity.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250814
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    Synthesis and Diels-Alder Reactions of 1,2-Dimethylene- and 1,2,9,10-Tetramethylene[2.2]paracyclophane: New Routes to Bridge-Anellated [2.2]ParacyclophanedienesDedicated to Professor Hans-Friedrich Grützmacher on the occasion of his 60th birthday. (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1895-1898 
    Details
    ISSN: 0009-2940
    Keywords: Bisdienes ; Diels-Alder reaction with p-benzoquinone ; p-Cyclophanes, bridge-anellated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 8 and 1 have been synthesized in three steps each from 1,2-dibromo[2.2]paracyclophan-1-ene (2) and 1,2,9,10-tetrabromo[2.2]paracyclophane-1,9-diene (4), respectively. Copper-mediated coupling of vinyl bromides 2 and 4 with methyl- and phenylmagnesium bromide gives substituted [2.2]paracyclophanes 3-CH3, 3-Ph, 5-CH3, and 5-Ph in good yields. The high reactivity of the [2.2]paracyclophane-1,2-dimethylene moieties in 8 and 1 in Diels-Alder reactions has been verified in cycloadditions with p-benzoquinone to give 10 and 13 and with naphthalene 1,4-endoxide to yield 12.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250817
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  • 197
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    Stereochemie der Denitrogenierung von optisch aktivem 9,10-Dihydro-5,6-diazalumibullvalen zu optisch aktivem 3,4-Dihydrosemibullvalen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1927-1937 
    Details
    ISSN: 0009-2940
    Keywords: Azo compounds, polycyclic ; Denitrogenation ; Pyrrolidines ; Semibullvalenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereochemical Course of the Denitrogenation of Optically Active 9,10-Dihydro-5,6-diazalumibullvalene to Optically Active 3,4-DihydrosemibullvaleneThermal decomposition of optical active diazalumibullvalene derivative (+)-6 gives optical active dihydrosemibullvalene (+)-5. The absolute configurations of optical active 6 and 5 were determined by correlation to tricyclooctanone 9 and 2-cyclopentene-1-acetic acid (21), respectively. From these results it is concluded that thermal denitrogenation of 6 occurs by concerted six-electron cycloreversion competing most likely to a multi-step N2 elimination via the symmetrical diradical intermediates 8 and 7.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250821
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  • 198
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    Imidazole Derivatives, VII. Reaction of 1-Acylimidazoles with Dialkyl Acetylenedicarboxylates: Synthesis of Imidazo[1,2-a]pyridines, (2-Imidazolyl)maleates, 1,5-Dihydroimidazo[1,2-a]pyridines, Furo[2′,3′: 2,3]pyrrolo[1,2-a]imidazoles, Furo[2′,3′: 2,3]pyrrolo[1,2-a]benzimidazoles and 7H-Pyrrolo[1,2-a]imidazoles (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1939-1951 
    Details
    ISSN: 0009-2940
    Keywords: 1-Acylimidazoles ; Dimethyl acetylenedicarboxylate ; 7H-Pyrrolo[1,2-a]imidazoles ; 1,5-Dihydroimidazo[1,2-a]pyridines ; Furo[2′,3′: 2,3]pyrrolo[1,2-a]imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 1-acylimidazoles with dialkyl acetylenedicar-boxylates provides novel functionalized imidazole derivatives by a sequence of electrophilic attack on the imidazole azine nitrogen atom and subsequent transprotonations and trans-acylations of the ylide generated in the first step. Based on this methodology we described a condensation of 1-arylacetylimid-azoles with DMAD in acetonitrile providing imidazo[1,2-a]pyridines. We have now achieved a control of the cyclization mode leading to a different ring system simply by varying the acyl side chain. Solvent and reaction temperature influence these cyclizations strongly, thus allowing the preparation of further novel imidazole derivatives including the hitherto unknown furo[2′,3′:2,3]pyrrolo[1,2-a]imidazole framework. Changing the parameters of the reaction of 1-alkanoylimidazoles with electron-deficient acetylenes allows the synthesis of (2-imidazolyl)maleates 1,5-dihydroimidazo[1,2-a]pyridines, furo[2′,3′:2,3]pyrrolo[1,2-a]imidazoles, furo[2′,3′: 2,3]pyrrolo[1,2-a]benzimidazoles, and 7H-pyrrolo[1,2-a]imidazoles. The crystal structures of compounds 14a, 26, and 31d have been determined by X-ray analysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250822
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  • 199
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    Masthead (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250901
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  • 200
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    Lanthanoiden-Komplexe, I Solvensfreie Alkoxid-Komplexe des Neodyms und Dysprosiums. Kristall- und Molekülstruktur von trans-Bis(acetonitril)tris(tri-tert-butylmethoxy)neodym (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1971-1979 
    Details
    ISSN: 0009-2940
    Keywords: Lanthanide alkoxides, siloxides ; Neodymium complexes ; Dysprosium complexes ; Thermochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes of the Lanthanides, I. - Solvent-Free Alkoxide Complexes of Neodymium and Dysprosium. Crystal and Molecular Structure of trans-Bis(acetonitrile)tris(tri-tert-butylmethoxy)neodymium The first lanthanide complex 3a is obtained from the sterically demanding silanol (tC4H9)3SiOH (, „silox“, 1a) and Nd-[N{Si(CH3)3}2]3 (2a). Similarly, the bulky alcohols, „tritox-H“, tri-tert-butylmethanol (1b), and, „ditox-H“, di-tert-butylmethanol (1c), react with 2a to give the corresponding alkoxide complexes Nd(tritox)3 (3b) and [Nd(ditox)3]2 (3c), respectively. Under the same conditions Dy[N{Si(CH3)3}2]3 (2b) yields the homoleptic ditox derivative 6. The new complexes are all very soluble in aliphatic hydrocarbons. They show a very different thermal stability as, for example, expressed in their sublimation behaviour.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250902
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