Tp*Cu(I)-CN-SiL2-NC-Cu(I)Tp*--a hexacoordinate Si-complex as connector for redox active metals via π-conjugated ligands

Hexacoordinate silicon complexes L2SiX2 (L = a 2-benzoylpyrrol-1-yl derivative, X = CN, NCS) were synthesized from L2SiCl2 by ligand exchange with trimethylsilyl reagents Me3SiX. In the presence of [Tp*CuNCMe] and Me3SiCN the silicon complex L2Si(NC(CuTp*))2 was obtained, which contains a linear Cu-CN-Si-NC-Cu unit (Tp* = hydrotris(3,5-dimethylpyrazolyl)borato).

Five-coordinate silicon(II) compounds with Si-M bonds (M = Cr, Mo, W, Fe): Bis[N,N'-diisopropylbenzamidinato(-)]silicon(II) as a ligand in transition-metal complexes

Reaction of the donor-stabilized silylene 1 with [Cr(CO)6], [Mo(CO)6], [W(CO)6], or [Fe(CO)5] leads to the formation of the transition-metal silylene complexes 2-5, which contain five-coordinate silicon(II) moieties with Si-M bonds (M = Cr, Mo, W, Fe). These compounds were characterized by NMR spectroscopic studies in the solid state and in solution and by crystal structure analyses. These experimental investigations were complemented by computational studies to gain insight into the bonding situation of 2-5. The nature of the Si-M bonds is best described as a single bond.

Novel neutral hexacoordinate silicon(IV) complexes with two bidentate monoanionic benzamidinato ligands

The novel neutral hexacoordinate bis(benzamidinato)silicon(iv) complexes 1-10 (SiN(4)X(2) skeletons; X = F, Cl, Br, C, N, S, Se) were synthesised and characterised by elemental analyses, single-crystal X-ray diffraction (except for 2) and NMR spectroscopy in the solid state and in solution. The dynamic behavior of 1 (SiN(4)Cl(2) skeleton) and 3 (SiN(4)F(2)) was additionally studied by variable-temperature NMR experiments. Compounds 1 and 2 (SiN(4)Br(2)) were obtained by reaction of SiCl(4) and SiBr(4), respectively, with two molar equivalents of the corresponding lithium amidinate. Compound 1 served as the starting material in the syntheses of 3-10, in which the two chloro ligands of 1 were substituted by two (pseudo)halogeno or one bidentate dianionic S,S, S,Se or Se,Se ligand. Compound 4 contains an SiN(4)C(2) skeleton and 5-7 contain an SiN(6) skeleton. With the preparation of 8 (SiN(4)S(2) skeleton), 9 (SiN(4)SSe) and 10 (SiN(4)Se(2)) it could be demonstrated that syntheses of hexacoordinate silicon(iv) complexes with soft chalcogeno ligand atoms are indeed feasible. Compounds 9 and 10 are the first hexacoordinate silicon(iv) complexes with Si-Se bonds.