Inorganic Chemistry, Vol.46, No.13, 5419-5424, 2007
Neutral hexa- and pentacoordinate Silicon(IV) complexes with SiO6 and SiO4N skeletons
The neutral heteroleptic hexacoordinate silicon(IV) complexes 4 and 5 (SiO6 skeletons) and the neutral pentacoordinate silicon(IV) complexes 7-9 (SiO4N skeletons) were synthesized, starting from the hexacoordinate precursor 2 and the pentacoordinate precursor 6, respectively. In these reactions, two monoanionic cyanato-N ligands are replaced by one dianionic bidentate O,O-chelate ligand. Compounds 4, 5, and 7-9 were characterized by single-crystal X-ray diffraction and solid-state and solution NMR spectroscopy. The chiral silicon(IV) complexes 4, 5, 7, and 8 were obtained as racemic mixtures, whereas 9 was isolated as a cocrystallizate consisting of the two diastereomers, (C,S)-9 and (A,S)-9 (ratio 1:1). The stereodynamics of 5 and 8 were studied by variable-temperature H-1 NMR experiments.