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  • 1
    Electronic Resource
    Electronic Resource
    Rearrangement of Bis(dimethylamino)bis(1-indenyl)diborane(4) into Bis(dimethylamino)bis(3-indenyl)diborane(4) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 505-509 
    Details
    ISSN: 1434-1948
    Keywords: Chlorobis(dimethylamino)(3-indenyl)diborane(4) ; Bis(dimethylamino)bis(1-indenyl)diborane(4) ; Bis(dimethylamino)(1-indenyl)(3-indenyl)diborane(4) ; Bis(dimethylamino)bis(3-indenyl)diborane(4) ; Rearrangement ; X-ray structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Indenyllithium reacts with dichlorobis(dimethylamino)diborane(4) with formation of bis(dimethylamino)bis(1-indenyl)diborane(4) which rearranges on heating to the isomer bis(dimethylamino)bis(3-indenyl)diborane(4). The „mixed” bis(dimethylamino)(1-indenyl)(3-indenyl)diborane(4) is obtained from indenyllithium and chlorobis(dimethylamino)(3-indenyl)diborane(4). The main structural differences between the two isomers 3 and 4 are a slightly shorter B-B bond in 4, as well as a stronger twist about the B-B bond (89.9° vs. 67.4°) and, as expected, a shorter B-C bond. There is, however, no significant B-C π bonding.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and Structures of Dimesityldiboranes(4) (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1519-1527 
    Details
    ISSN: 1434-1948
    Keywords: B,B′-Dimesityldiborane(4) dihalides ; B,B′-Diamino-B,B′-dimesityldiboranes(4) ; B,B′-Di-tert-butyloxy-B,B′-dimesityldiborane(4) ; B,B′-Dimesityl-B,B′-di(organylthio)diborane(4) ; NMR spectroscopy ; X-ray structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient route to B,B′-dihalo-B,B′-dimesityldiboranes(4) is reported, as well as the conversion of these and of B,B′-dimesityl-B,B′-dimethoxydiborane(4) into other B,B′-dimesityldiboranes B2mes2X2 (X = OR, SR, NR2, NHR). The substituents X influence the shielding of the 11B nucleus in the expected manner. Hindered rotation about the B-N bond is observed for X = pyrrolyl, while in solution there is free rotation about the B-C bond. However, X-ray structural results reveal that the mesityl group is almost orthogonal to the B(B)CY plane in the solid state. The shortest B-B bond is observed in mes2B2I2, indicating that the iodide is the strongest Lewis acid in the reported series of mes2B2Y2 compounds. This is also reflected in short B-C bonds. Moreover, the two mes(Y)B units also approach orthogonality in these diborane(4) compounds, and thus enforce this as a typical structural feature of diborane(4) derivatives. For this reason, the planar C(N)B-B(N)C unit of B,B′-di(benzylamino)-B,B′-dimesityldiborane(4) is regarded as exceptional for aminodiboranes(4).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    A Boron-Boron Double Bond in the Dianions of Tetra(amino)diborates (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1931-1937 
    Details
    ISSN: 1434-1948
    Keywords: Diboron compounds ; B-B double bond ; Dilithium tetra(amino)diborates(2-) ; Structure elucidation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of mixed tetraaminodiborane(4) compounds bearing pyrrolyl, indolyl, and carbazolyl substituents besides dimethylamino groups has been prepared and subjected to reduction with elemental Li in the presence of diethyl ether. Tetraaminodiborates(2-) are formed, which feature a boron-boron double bond. The diborate anion acts as a double bidentate ligand coordinating pairwise through two of its nitrogen atoms to an Li center, which is tricoordinated by one O and the two N atoms. The new diborates are isoelectronic with tetraaminoethylenes and are expected to be electron-transfer reagents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Tetrasupersilyl-tristannaallene and -tristannacyclopropene (tBu3Si)4Sn3 - Isomers with the Shortest Sn=Sn Double Bonds to Date (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1211-1218 
    Details
    ISSN: 1434-1948
    Keywords: Double Bonds ; NMR Spectroscopy ; Silicon ; Tin ; X-ray structure analyses ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dark blue, air- and moisture-sensitive, thermolabile tristannaallene R*2Sn=Sn=SnR*2 (5) (R* = SitBu3) is prepared by reaction of Sn(OtBu)2 or Sn[N(SiMe3)2]2 with R*Na in pentane/benzene at -25°C. The dark red-brown, air-sensitive, moisture-insensitive, and thermostable cyclotri-stannene R*4Sn3 (6) with a -R*Sn=SnR*- moiety as part of a Sn3 ring is obtained from the reaction of Sn(OtBu)2 or Sn[N(SiMe3)2]2 with R*Na in pentane at 25°C or from the isomerization of 5 at room temperature (τ1/2 = 9.8 h). According to the result of X-ray structural analyses the Sn3 framework of chiral 5 is bent (156°) and the terminal Sn atoms have pyramidal surroundings. The SnSn double bonds in 5 (2.68 Å) are shorter than those found for the hitherto structurally investigated distannenes (2.77-2.91 Å). Even shorter is the double bond in 6 (2.59 Å). The unsaturated Sn atoms here have nearly planar surroundings in perfect analogy to the carbon atoms in CC double bonds. The SnSn double bond in 6 can therefore be considered as the first “true” Sn=Sn bond. The structures of 5 and 6 can be deduced also from 119Sn- and 29Si-NMR studies in solution.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and Homomolecular Metalation of Trialkylsilylphosphanides of Calcium and Barium (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 743-750 
    Details
    ISSN: 1434-1948
    Keywords: Arsenic ; Barium ; Calcium ; Metalations ; NMR spectroscopy ; Phosphorus ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metalation of triisopropylsilylphosphane with bis(tetrahydrofuran-O)calcium bis[bis(trimethylsilyl)amide] in tetrahydropyran (thp) in a molar ratio of 3:2 yields (Me3Si)2NCa[μ-P(H)SiiPr3]3Ca(thp)3 (1) containing a trigonal-bipyramidal Ca2P3 core, the metal atoms occupying apical positions. Reaction of two equivalents of triisopropylsilylphosphane or -arsane with bis(tetrahydrofuran-O)barium bis[bis(trimethylsilyl)amide] in tetrahydrofuran gives the corresponding bis(phosphanide) 2 and bis(arsanide) 3, compounds of the type (thf)3Ba[μ-E(H)SiiPr3]Ba(thf)2E(H)SiiPr3 with E = P, As. The equimolar reaction of (tri-tert-butylsilyl)phosphane with (thf)2Ba[N(SiMe3)2]2 in toluene yields heteroleptic dimeric (thf)2Ba[N(SiMe3)2][P(H)SitBu3] (4). Addition of a further equivalent of H2PSitBu3 leads to the formation of homoleptic (thf)nBa[P(H)SitBu3]2 (5). Dissolution of the latter in aromatic hydrocarbons leads to the elimination of H2PSitBu3, yielding dimeric (thf)Ba3(PSitBu3)2[P(H)SitBu3]2 (6). The inner core of 6 consists of the tetramer (BaPSitBu3)4 based on a Ba4P4 heterocubane unit, two opposite faces being capped with (thf)Ba[P(H)SitBu3]2 molecules.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation and Structural Characterization of Lithium Silylborates (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 817-823 
    Details
    ISSN: 1434-1948
    Keywords: Lithium (triphenylsilyl)trihydridoborate ; Lithium (tert-butyldiphenylsilyl)trihydridoborate ; Lithium tris(trimethylsilyl)methylborate ; Lithium tetrakis(trimethylsilyl)borate ; X-ray structure analysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Borane triethylamine reacts with lithium triphenylsilanide or lithium tert-butyldiphenylsilanide with formation of lithium (triphenylsilyl)trihydridoborate or lithium (tert-butyldiphenylsilyl)trihydridoborate. Complexation of the lithium cation with various ligands allows the isolation of compounds 1, 2a, and 2b. Trimethoxyborane reacts with lithium trimethylsilanide to form lithium tetrakis(trimethylsilyl)borate 3 and lithium tris(trimethylsilyl)methylborate 4. Mixed single crystals of 3 and 4 show an unexpected coordination of the lithium cation due to the lack of any supporting donor molecule. All silylborates exhibit short Si-B bond lengths compared to tricoordinated silylboranes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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