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  • Articles: DFG German National Licenses  (7)
  • Boranes  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Electron-Poor 2,3-Dihydro-1,3-diborolyl Ruthenium Compounds: Synthesis, Complexation, Oxidative Addition, Capping, and Stacking Reactions (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1685-1692 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; Ruthenium ; Sandwich Complexes ; Diboroles ; Triple-decker ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition products of lithium alkyls and the pentaalkyl-2,3-dihydro-1,3-diborole derivatives 5a-f react with [{(C5Me5)RuCl}4] and [{(C5Me4Et)RuCl}4] to form the violet sandwich compounds 2*c-f and 2∧c, f. These formally 16 VE complexes are in fact electron-poor 18 VE species, because a high-lying combination of σ(B-C) orbitals interacts with the dxz orbital of the Ru atom. Addition of tert-butyl isocyanide to 2*a, or 2*d leads to the isonitrile complexes 6*a, and 6*d, as indicated by the spectroscopic data and X-ray structure analyses. At low temperature the interaction of 2*a, c, or e with H2 yields the classic dihydride complexes 7*a, c, and e, respectively, which have been studied by NMR. Oxidative addition of H3B·THF to the ruthenium atom of 2*a or c, followed by a reductive elimination of H2 and migration of the boranediyl group gives the yellow closo-RuC3B3 ruthenacarboranes 8*a and 8*c, respectively. The reaction of [(C2H4)2RhCl]2 and 2*c generates the tetranuclear complex 9*c.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of Tetraborylethenes and 1,1,1′,1′-Tetra- and Hexaborylethanes; Electronic Interactions in Tetraborylethenes and 1,1,1′,1′-Tetraborylethanes, and HF-SCF Calculations (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1693-1700 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; Homogeneous catalysis ; Ab initio calculations ; Donor-acceptor systems ; X-ray analysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The catechol-substituted diboranes(4) 1 react with the catechol-substituted diborylacetylenes 2, in the presence of [Pt(PPh3)2(C2H4)] or [Pt(PPh3)4], to give tetra- and hexaborylethane derivatives. When [Pt(cod)2] is used as catalyst, the tetraborylethene 5a is formed exclusively. Catalytic hydrogenation of 5a affords the 1,1,1′,1′-tetraborylethane 4a, which has been studied by an X-ray structure analysis. Natural Bond Orbital (NBO) analyses for the RHF/3-21G optimized geometries of 4a and 5a reveal intramolecular stabilization of the boron pz orbital. This covers B-O, B-B, and agostic interactions. The photoelectron spectrum of 5a is reported
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Syntheses, Structures, and Coordination of Diborylbipyridines and Bipyridinediborates (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 393-398 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; Bipyridine ; Crystal structures ; Donor-acceptor interaction ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 6,6′-Bis(diethylboryl)-2,2′-bipyridine (1a) was obtained in low yield by in situ deprotonation of 2,2′-bipyridine in the presence of diethyl(methoxy)borane. 6,6′-Dilithio-2,2′-bipyridine reacts with various alkoxyboranes leading to bipyridinediborates 2 in good yields. The derivatives 2b and 2c allow the formation of the free diborylbipyridines 1b and 1c. The coordination properties of the diboryl-bipyridines as tetrafunctional donor-acceptor compounds have been used for the formation of the copper complex 4 and of the adduct 5 which is built from diborylbipyridine and a dihydroxydiboroxan derivative. The composition of the products follows from spectroscopic data and from X-ray structure analyses for 2f, 4, and 5.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Cyclic Ketiminoboranes (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 7-9 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; Diazaboroles ; Heterocycles ; Ketiminoboranes ; Crystal Structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclocondensation reaction of benzil-bis(trimethylsilylimin) (3) and Cl2B-NiPr2 via silicon-boron exchangeresults in the solvent-dependent formation of the 1,3,2-diazaborole 1a or the 1,3,6,8,2,7-tetraazadiborecin 2a. Using the more rigid 9,10-bis(trimethylsilylimino)phenanthrene instead of 3 only the five-membered heterocycle 4,5-biphenylene-2-diisopropylamino-1,3,2-diazaborole (1b) is formed. The cyclic ketiminoboranes are characterized by NMR and X-ray diffraction data. The 1,3,2-diazaborole ring is almost planar, while the conformation of the 1,3,6,8,2,7-tetraazadiborecin has the shape of a figure-eight loop.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Syntheses, Structures, and Reactivity of 2,5-Diboryl-1-alkylpyrroles and Di(1-alkyl-2-pyrrolyl)boranes (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 399-404 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; 1-Alkylpyrroles ; Porphyrinogenes ; Lithiation ; Tin-boron exchange ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 2,5-dilithiated 1-methylpyrrole (1a) with ClB(NR2)2 lead to the novel 2,5-diboryl-1-methylpyrroles 2a and 2b. Accordingly, 2,5-diboryl-1-benzylpyrrole 2d is obtained. 1a and Cl2BNiPr2 form the aminochloroboryl-substituted derivative 2c and the di(5-boryl-2-pyrrolyl)borane 4 in 29% and 15% yield, respectively. The 2,5-distannyl-1-methylpyrrole 1c is used for the synthesis of the aryloxy-boryl derivative 2e. Reacting monolithiated 1-methyl- and 1-benzylpyrroles with Cl2BNiPr2 yields the di(2-pyrrolyl)boranes 3e and 3f, respectively. NMR and MS data are in agreement with the compositions of the compounds, which are confirmed by X-ray structure analyses for 2a, 2b, 2d, und 3e.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Nucleophilic Substitution Reactions with the 3-Borane-1,4,5-trimethylimidazol-2-ylidene Anion. - Unexpected Formation of an Imidazabole Isomer (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 789-793 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; Carbenes ; Heterocycles ; Imidazoles ; X-ray structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nucleophilic carbene 3-borane-1,4,5-trimethylimidazol-2-ylidene anion (1-) reacts with the electrophiles CH3I, (CH3)3SiCl, (CH3)3SnCl, and the bromodiazaboroline 7 to form the 2-substituted imidazoles 4, 5, 6, and 8. With triethylborane, the anionic carbene borane adduct 9- is obtained. An unexpected result was achieved when chlorodimethoxyborane and HBCl2 · S(CH3)2 were used as electrophiles. In both cases only the imidazabole 14a could be isolated. Imidazole 5, the imidazole borane adduct 3a and the imidazabole 14a were characterized by X-ray structure analyses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Borane-Substituted Imidazol-2-ylidenes: Syntheses, Structures, and Reactivity⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 843-849 
    Details
    ISSN: 1434-1948
    Keywords: Boranes ; Carbenes ; Carbene complexes ; Heterocycles ; Imidazoles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of the Lewis acids BH3 and BEt3 with trimethylimidazole (1) lead to the borane adducts 2a and 2b. Deprotonation of 2a with n-butyllithium results in the formation of the novel N-borane-substituted imidazol-2-ylidene anion 3a- whereas deprotonated 2b rearranges unexpectedly to the anionic compound 3b-. This can be transformed into the carbene-borane adduct 4 by methylation. The reaction of 3a- with [Mn(CO)5Br] yields the carbene complex 5. Surprisingly, 3a- attacks Fe(CO)5 at a carbon atom which leads to the iron acyl complex anion 6-. The compositions of the products follow from spectroscopic and analytical data and from X-ray structure analyses for Li(thp)+3a-, Li(thf)2+3b- and Li(thp)3+6-.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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