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  • 1
    Digitale Medien
    Digitale Medien
    A Methylene-Bridged Dialuminium Compound as a Chelating Lewis Acid: Complexation of Nitrite and Nitrate Anions by R2Al-CH2-AlR2[R = CH(SiMe3)2]⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 921-926 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Aluminium ; Chelates ; Lewis acids ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Sodium nitrite (NaNO2) dissolves readily in THF, when the methylene-bridged dialuminium compound R2Al-CH2-AlR2 [R = CH(SiMe3)2] 1 with two coordinatively unsaturated aluminium atoms is added. Compound 1 reacts as a chelating Lewis acid, and, as shown by a crystal structure deter-mination of the [Na([18]crown-6)(Et2O)]+ derivative 5c, a compound (5) is formed, in which one oxygen atom and the nitrogen atom of the nitrite ion are each coordinated by one aluminium atom to form a five-membered Al2CNO hetero-cycle. The second oxygen atom of the nitrite anion is not affected. Similarly, lithium nitrate (LiNO3) reacts with 1 to yield a THF soluble product (6a). Single crystals were obtain-ed of the [Li(N,N′,N′′-trimethyltriazinane)2]+ derivative 6c, whose structure shows each aluminium atom to be coordinated by one oxygen atom of the nitrate ion to give a six-membered Al2CNO2 heterocycle.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    The Formation of Macrocyclic Compounds Containing Two Ga-Ga Bonds by the Reaction of Tetraalkyldigallane(4) R2Ga-GaR2 [R = CH(SiMe3)2] with Dicarboxylic Acids (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1661-1665 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Gallium ; Low-valent compounds ; Macrocycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Tetrakis[bis(trimethylsilyl)methyl]digallane(4) 1 reacts with dicarboxylic acids like 1,4-benzenedi(methylcarboxylic) acid, 1,4-cyclohexanedicarboxylic acid, 1,6-hexanedicarboxylic acid, and 1,4-butanedicarboxylic acid (adipinic acid) by the release of two equivalents of bis(trimethylsilyl)methane and the retention of the Ga-Ga bond. Products are formed, in which the very short Ga-Ga bonds (237.7 pm on average) are bridged by two carboxylato groups. Two of these moieties are connected in each compound by two spacers (dimethylbenzene, cyclohexane, hexane, or butane) to form macrocyclic compounds with up to 22 atoms in the resultant heteroatomic rings. The dimeric form is also observed in solution. For comparison, the synthesis and structure of the product of the reaction of 1 with 1-adamantanecarboxylic acid is included, which also has the Ga-Ga bond (239.1 pm) bridged by two carboxylato groups.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Diazomethane Derivatives Bearing Dialkylaluminium or DialkylgalliumSubstituents - The Isomeric Diazomethane and Nitrile Imine Structures Realized by the Different Coordination Behavior of Aluminium and Gallium (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 771-776 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Aluminium ; Gallium ; Diazo compounds ; Dimerization ; Coordination modes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Lithium trimethylsilyldiazomethanide Li(SiMe3)CN2 reacted with the dialkylaluminium or -gallium halides R2AlCl and R2GaBr [R = CH(SiMe3)2] by the elimination of lithium halide and the formation of the corresponding aluminium or gallium diazo compounds. As shown by a crystal structure determination, the gallium derivative 1 adopts the nitrile imine structure, in which the gallium atom is coordinated by the terminal nitrogen atom of the diazo group. The N-N-C-Si moiety is almost ideally linear with N-N and C-N bond lengths of 125.5 and 115.9 pm on average. In contrast, the diazomethane structure was formed with dialkylaluminium chloride, and the aluminium atom in 2 is attached to the carbon atom of diazomethane. The almost linear N-N-C group (174.1°) has N-N and N-C distances of 120.0 and 126.4 pm, respectively, inverse to that of the gallium derivative. The bonding situations can best be described by the resonance structures R-C≡N+-N--GaR2 for 1 and R2Al-(R)C=N+=N- for 2. The nitrile imine isomer of the aluminium compound could be detected by NMR spectroscopy as a by-product. Both compounds gave dimers in the solid state, a Ga2N2 four-membered heterocycle was formed of 1, while an eight-membered Al2C2N4 heterocycle resulted with 2.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Silylene Reactions with Nitrogen Multiple Bonds: Additions and Rearrangements (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1755-1758 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Silicon ; Silylene ; Azobenzene ; 1-Adamantyl azide ; Addition reactions ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactions of the sterically encumbered silylenes R2Si: (R = 2,4,6-Me3C6H2, 2,4,6-iPr3C6H2) with azobenzene are thought to proceed via the [2+1] cycloaddition products, followed by insertion of the N-N single bond into the ortho-C-H bond of one of the phenyl rings or into the C-HMe2 bond of one of the ortho-isopropyl groups to furnish the 1,3-diaza-2-silaindan (4) or 1-aza-2-silaindan (5) derivatives, respectively. The reactions of these silylenes with 1-adamantyl azide seem to proceed through the silanimines and 4-azahomoadamantene intermediates which, by [2+2] cycloadditions, afford the 1,3-diaza-2-silacyclobutane derivatives 11 and 12. The structures of 4, 5, 11, and 12 were determined by X-ray crystallography.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    A Heteroleptic Diplumbene and a Magnesium Dibromide Stabilized Plumbylene Dimer (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 579-582 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Lead ; Plumbylenes ; Plumbanediyles ; Diplumbene ; Plumbylene dimers ; Double-bond systems ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Treatment of the diarylplumbylene R2Pb: (R = 2,4,6-iPr3C6H2) with the disilylplumbylene R′2Pb: [R′ = Si(SiMe3)3] furnishes the heteroleptic plumbylene RR′Pb: which exists as the diplumbene RR′Pb=PbRR′ (7) in the solid state. The X-ray structure analysis of 7 reveals a trans-bent angle of 42.7° and a Pb-Pb bond length of 298.99(5) pm, the shortest observed so far for diplumbenes with a lead-lead double bond. Reaction of mesitylmagnesium bromide with PbCl2 yielded black crystals of an MgBr2 stabilized dimesitylplumbylene dimer with a large trans-bent angle of 71°, a lead-lead separation of 335.49(6) pm, and long Pb···Br contacts of 315.71(8) pm.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Silylene Reactions with Buta-1,3-diynes: Cycloadditions, Insertions, and Rearrangements (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2301-2307 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Multiple bonds ; Silicon ; Silylene ; Cycloadditions ; Insertions ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Di-tert-butylsilylene, generated by photolysis of hexa-tert-butylcyclotrisilane 1 or 1,1-di-tert-butyl-trans-2,3-dimethyl-silirane (2), reacts with the 1,3-diyne (tBu-C≡C-)29 to furnish the dialkynylsilane 11 via the isolable alkynylsilirene 10. Photolysis of excess 1 in the presence of 9 furnishes the C-C linked 2,2′-disilirene 12 which, upon prolonged irradiation, rearranges to the 2,5-disilabicyclo[2.2.0]hexa-1(6),3-diene (13). Treatment of 9 with diarylsilylenes, formed by irradiation of hexamethyl-2,2-dimesityltrisilane (3) or hexamethyl-2,2-bis(2,4,6-triisopropylphenyl)trisilane (4), gives the corresponding alkynylsilirenes 14 and 15, respectively. Photolysis of 1 or 2 in the presence of (Me3Si-C≡C-)216 yields the dialkynylsilane 17 which, on further reaction with 2, yields the 2,5-disilabicyclo[2.2.0]hexa-1(6),3-diene (18). Irradiation of 3 in the presence of 16 affords the cis- and trans-isomeric 1,3-dimethylene-2,4-disila-cyclobutane derivatives cis-21 and trans-21, presumably via a 1-silaallene intermediate. The structures of 12, 15, 18, cis-21, and trans-21 have been determined by X-ray crystallography.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Hexakoordinierte Schwefel(VI)- und Ψ-hexakoordinierte Schwefel(IV)-Anionen (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 427-432 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Pentafluorooxosulfate ion ; Sulfur anions, fluorine-containing ; Sulfur tetrafluoride derivatives ; Tris(dimethylamino)sulfonium difluorotrimethylsilicate ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Hexacoordinated Sulfur(VI) and Ψ-Hexacoordinated Sulfur(IV) Anions(Me2N)3S+OSF-5 (3) was prepared from OSF4 and (Me2N)3S+Me3SiF-2 („TAS fluoride“, 1). From 1 and SF4, CF3SF3, and (CF2)2CFSF3, TAS+SF-5 (5a), TAS+CF3SF-4 (5b), and TAS+ (CF3)2CFSF-4 (5c) were obtained. Spectroscopic data of these salts and the crystal structure of 3 are reported.
    Notizen: (Me2N)3S+OSF-5 (3) wurde aus OSF4 und (Me2N)3S+ Me3SiF-2 („TAS-Fluorid“, 1) dargestellt. Aus SF4, CF3SF3, (CF3)2CFSF3 und 1 entstehen TAS+SF-5 (5a), TAS+CF3SF-4 (5b) und TAS+ (CF3)2CFSF-4 (5c). Die spektroskopischen Daten dieser Salze und die Kristallstruktur von 3 werden mitgeteilt.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19891220306
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  • 8
    Digitale Medien
    Digitale Medien
    Bis[tris(trimethylsilyl)methyl]diselenid: Ein ungewöhnliches Dichalkogenid mit sterisch erzwungener trans-C2h-Konformation (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2325-2327 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Diselenide, torsion angle/NMR, 77Se/Selenenyl halide ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bis[tris(trimethylsilyl)methyl] Diselenide: An Unusual Diselenide with Sterically Enforced trans-C2h ConformationDeselenation of bis[tris(trimethylsilyl)methyl] triselenide (1) with copper occurs with formation of bis[tris(trimethylsilyl)-methyl] diselenide (2) and minor amounts of 3,3,5,5-tetrakis(trimethylsilyl)-1,2,4-triselenolane (3). The structures of 2 and 3 have been studied by multinuclear NMR spectroscopy and by X-ray crystallography. The C—Se—Se—C moiety of 2 adopts an unusual antiperiplanar conformation. Cleavage of the Se — Se bond by iodine providing iodo[tris(trimethylsilyl)-methyl]selane (5) is complete with 2, but reversible with 1.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19901231215
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  • 9
    Digitale Medien
    Digitale Medien
    Lithium-(2,4,6-tri-tert-butylphenylselenid); Erzeugung, Struktur und Reaktionen unter Knüpfung von Se -P-, Se - C-, Se - Si-, Se - Sn- und Se - Au-Bindungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1315-1320 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chalcogen-chalcogen bonds ; Selenium ; Selenide (2,4,6-tri-tert-butylphenyl)- ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Properties of Chalcogen-Chalcogen Bonds, XV1). - Lithium 2,4,6-Tri-tert-butylphenylselenide: Synthesis, Structure, and Reactions with Formation of Se - P, Se - C, Se - Si, Se - Sn, and Se - Au BondsBis(2,4,6-tri-tert-butylphenyl)diselenide (1) is reduced by lithium triethylhydridoborate to give lithium 2,4,6-tri-tert-butyl-phenylselenide (2) in high yield. 2 crystallizes with three molecules of tetrahydrofuran coordinated to lithium ([2(THF)3] ≡ 2a, space group P&1macr; Z =4). The monomeric compound 2a contains four-coordinate lithium bonded to two-coordinate selenium. 2 (LiSeR) reacts with the nonmetal and metal halides tBu2PCl, CH2Cl2, Me3SiCl, Me3SnCl, and Ph3PAuCl to give tBu2PSeR (3), RSeCH2Cl (4), (RSe)2CH2 (5), Me3SiSeR (6), Me3SnSeR (7), and the novel gold(I) selenophenolate derivative Ph3PAuSeR (8)(R = 2,4,6-tri-tert-butylphenyl).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240602
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  • 10
    Digitale Medien
    Digitale Medien
    Siliciumverbindungen mit starken intramolekularen sterischen Wechselwirkungen, 47. Trisilacyclobutanimine (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1043-1046 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Trisilacyclobutanimines ; Cyclotrisilane, hexa-tert-butyl- ; Isocyanide insertion reactions ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Silicon Compounds with Strong Intramolecular Steric Interactions, 47[1]. - TrisilacyclobutaniminesTreatment of hexa-tert-butylcyclotrisilane (4) with aryl isocyanides leads to the trisilacyclobutanimines 5-8. Reaction of the 1,4-diisocyanobenzene derivative 7 with two molecules of 4 leads to the double insertion product 9, the X-ray structure analysis of which shows the Si3CN framework atoms to be almost exactly coplanar. The planes of the two four-membered rings are strictly parallel whereas the linking phenylene group forms a 71.67° angle with these planes. The most striking features of these and of related compounds are their dark colours with longest wavelength absorptions between 500 and 540 nm.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19921250510
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