1211544-08-9Relevant articles and documents
Neutral pentacoordinate group 14 compounds with β-diketonato ligands
Bombicz, Petra,Kovacs, Ilona,Nyulaszi, Laszlo,Szieberth, Denes,Terleczky, Peter
, p. 1100 - 1106 (2010)
A stable neutral pentacoordinate germanium compound substituted with three CF3 and a dibenzoylmethane ligand was synthesized. Single-crystal X-ray diffraction structure determination proves the presence of two crystallographically independent molecules in the asymmetric unit, one of them deviating somewhat from planarity. Density functional computations show the isolated molecule to be planar, while the computation of a molecule pair yielded a minimum, where the planarity of the two monomeric units differ from each other, with the resulting structure resembling the unit cell in the crystal. Bader analysis revealed this molecule pair to be bound together by hydrogen bonds. The stability of the pentacoordinate bond in this compound is about 23 kcal/mol at the B3LYP/6-31+G* (31 kcal/mol at the MP2/6-31+G*// B3LYP/6-31+G*) level. The stabilizing effect of the trifluoromethyl substituent on the pentacoordinate structure is comparable to that of the fluorine group. Computations on the analogous Si-containing systems reveal similar pentacoordinate structures, even though the relative stabilities of these structures are somewhat different for the two group 14 elements. For example, germanium substituted by three -OEt moieties forms a stable pentacoordinate structure with the acetylacetone (acac) ligand (explaining the role of acac as hydrolysis inhibitor of tetraethoxygermane), while the hypervalent bond of the silicon analogue is unstable at the B3LYP/6-31+G* level.
