Showing papers on "Carbon group published in 1996"

Hexacoordinated Group‐14 Elements with Phosphorus Donor Ligands: Syntheses and Structures of Cl2E[C(PMe2)2(SiMe3)]2 (E = Si, Ge, Sn)

Abstract: The group-14 tetrahalides ECl4 (E = Si, Ge, Sn) react with two equivalents of Li[C(PMe2)2(SiMe3)] to give the trans-hexacoordinated complexes Cl2E[C(PMe2)2(SiMe3)]2, which were characterized spectroscopically and by structure determinations in the solid state. The complexes were found to crystallize with or without tetrahydrofuran (THF) molecules, depending on the presence or absence of this solvent. In the case of the silicon complex, the structures of both crystal forms were determined, showing slightly different molecular structures of the complexes in the solid state. Without cocrystallized THF, Cl2Si[C(PMe2)2(SiMe3)]2 has no crystallographically imposed molecular symmetry, while in the presence of THF its crystallographic symmetry is C2h (2/m). The tin and germanium complexes were crystallized either with and without THF molecules, respectively, their crystal structures being isotypic with the respective ones of the silicon complex. In all cases, small amounts of the cis-hexacoordinated isomers were also observed in solution, but only in the case of the silicon complex, it was isolated in pure form. It rearranges to the trans isomer at ambient temperature. trans-Cl2Si[C(PMe2)3]3, trans-Cl2Si[C(PPh2)2(SiMe3)]2 and cis-Me2-Si[C(PMe2)2(SiMe3)]2 were likewise obtained.

Design, Synthesis, and Electrochemical Behavior of New Electron Donors Based on β‐Effects of Group 14 Elements in Electron Transfer.

Abstract: In a program aimed at new electron donors, we synthesized several silicon- and tin-substituted 1,3-benzodithioles which exhibited much lower oxidation potentials than 1,3-benzodithiole. This effect was supported by the molecular orbital calculations.