AN ABINITIO STUDY OF SIMPLE 1,3-CYCLODISILOXANE DERIVATIVES

Ab initio geometry optimizations on some simple cyclodisiloxane derivatives (R2SiO)2 (R = CH3, OH and OCH3) and on their radical cations have been carried out at the restricted Hartree-Fock (RHF) level using the basis set 3-21G*. Mayer's bond orders and valences have been calculated for all these species using the STO-3G* basis set, employing geometries determined at the RHF/3-21G* level. It was found that the geometries of the neutral and charged species are quite different, but the geometry of the ring and Mayer's bond indices are affected relatively slightly by the substituents. The small but characteristic Si...Si bond orders in neutral cyclodisiloxanes indicate a weak Si...Si bond. While this bond is considerably weaker in the molecular ions, the O...O bond orders are increased in the charge species.