Quantum chemical study of silicon pentacoordination in (aroyloxymethyl) trifluorosilanes and their analogs

Pentacoordinated silicon compounds of the series 4-XC6H4C(O)O(CH2)(m)Si(CH3 )(3-n)F-n (m = 1, 2; n = 1, 2, 3) with an intramolecular O-->Si bond are st udied by ab initio and semiempirical (AM1) quantum chemical methods. The re sults are compared with published experimental data. The C6H5C(O)OCH2SiF3 m olecule for it's geometry optimization is calculated by the MP2 method incl uding electron correlation. This leads to considerable improvement agreemen t between the calculated coordination energy (25.3 kJ/mole) and the experim ental value (28.5 kJ/mole). The geometry and the dipole moment calculated b y both ab initio (HF/6-31G*//HF/6-31G*) methods and by the AM1 method are i n satisfactory agreement with the experimental data.