STRUCTURE AND BONDING OF ORGANOSILICON COMPOUNDS CONTAINING SILICON-SILICON AND SILICON-GERMANIUM BONDS - AN X-RAY-ABSORPTION FINE-STRUCTURE STUDY

Si K-edge X-ray Absorption Fine Structures (XAFS) spectroscopy has bee n used to study the structure and bonding of a series of highly symmet ric organosilicon compounds, Si(CH3)(4), Ge[Si(CH3)(3)](4), Si[Ge(CH3) (3)](4), and Si[Si(CH3)(3)](4), in the gas phase. It was found that th ere is a significant difference in the absorption coefficient in the n ear-edge region between local Si-Si interactions-in these compounds an d long-range Si-Si interactions in crystalline solids and that the Si- Si bond length in the molecule Si[Si(CH3)(3)](4) is 2.364(10) Angstrom and the Si-Ge bond lengths in Si[Ge(CH3)(3)](4) and Ge[Si(CH3)(3)](4) are 2.38(3)Angstrom and 2.396(15) Angstrom, respectively. These resul ts and their comparison to Si-Si and Si-Ge interatomic distances in cr ystalline solids are discussed.