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Germanium Compounds (germanium + compound)
Selected AbstractsNovel Hypervalent Complexes of Main-Group Metals by Intramolecular Ligand,Metal Electron Transfer*CHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2004Matthias Driess Prof. Dr. Abstract New fascinating electronic features of the simple diketoamine chelate ligand HN[CH2C(tBu)O]2 (1) are described. Unexpectedly, the corresponding trianionic amido-dienolate form of 1 is capable of reducing main-group metal atoms M after initial coordination and intramolecular L,M two-electron transfer and of stabilizing main-group elements in unusual low oxidation states. This is impressively shown by the synthesis and structural characterization of the novel Ge and Sn complexes 4,6 by redox reactions of lithiated 1 with the corresponding metal halides GeCl4 and MCl2 (M=Ge, Sn). Surprisingly, conversion of tris-lithiated 1 with GeCl4 readily consumes two molar equivalents of GeCl4 and results in the formation of the neutral GeCl3 complex 4 and GeCl2. The former represents the second example of a structurally characterized neutral octahedrally coordinated germanium compound. Reaction of dilithiated 1 with GeCl2 does not lead to the expected ClGe(+2) complex but affords the novel dimeric germylene 5, whereas similar reaction using SnCl2 furnishes the monomeric stannylene (ClSn(+2) complex) 2 and elemental tin due to the higher oxidation potential of Sn(+2). Unexpectedly, a similar redox reaction of dilithiated 1 with PbCl2 furnishes the first air- and water-stable lithium 1,2-diketoimine,enolate 7 and elemental lead. Compound 7 is tetrameric in the solid state and consists of a strongly distorted Li4O4 cubic core with trigonal-bipyramidal coordinated Li+ ions. [source] High-resolution solid-state 73Ge NMR spectra of hexacoordinated germanium compoundsMAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2004Yoshito Takeuchi Abstract High-resolution solid-state magic angle spinning 73Ge NMR spectra of hexavalent germanium compounds, i.e. diiodogermylene (1a) and bis(1-pyrrolyl)(meso -tetraphenylporphyrinato)germanium (3a), were determined. To the best of our knowledge, this is the first example of high-resolution solid-state 73Ge NMR spectra of hexacoordinated germanium nuclei. The symmetry requirement for observation of high-resolution solid-state 73Ge NMR spectra is discussed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Stable N-Heterocyclic Carbene Adducts of Arylchlorosilylenes and Their Germanium HomologuesCHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2010Alexander Abstract The first N-heterocyclic carbene adducts of arylchlorosilylenes are reported and compared with the homologous germanium compounds. The arylsilicon(II) chlorides SiArCl(Im-Me4) [Ar=C6H3 -2,6-Mes2 (Mes=C6H2 -2,4,6-Me3), C6H3 -2,6-Trip2 (Trip=C6H2 -2,4,6- iPr3)] were obtained selectively on dehydrochlorination of the arylchlorosilanes SiArHCl2 with 1,3,4,5-tetramethylimidazol-2-ylidene (Im-Me4). The analogous arylgermanium(II) chlorides GeArCl(Im-Me4) were prepared by metathetical exchange of GeCl2(Im-Me4) with LiC6H3 -2,6-Mes2 or addition of Im-Me4 to GeCl(C6H3 -2,6-Trip2). All compounds were fully characterized. Density functional calculations on ECl(C6H3 -2,6-Trip2)(Im-Me4), where E=Si, Ge, at different levels of theory show very good agreement between calculated and experimental bonding parameters, and NBO analyses reveal similar electronic structures of the two aryltetrel(II) chlorides. The low gas-phase Gibbs free energy of bond dissociation of SiCl(C6H3 -2,6-Trip2)(Im-Me4) (,=28.1,kJ,mol,1) suggests that the carbene adducts SiArCl(Im-Me4) may be valuable transfer reagents of the arylsilicon(II) chlorides SiArCl. [source] | ||||||||||