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

Pentacoordinated silicon compounds of the series 4-XC₆H₄C(O)O(CH₂)_mSi(CH₃)_3-nF_n (m = 1, 2; n= 1,2,3) with an intramolecular 0→Si bond are studied by ab initia and semiempirical (AMI) quantum chemical methods. The results are compared with published experimental data. The C₆H₅C(O)OCH₂SiF₃ molecule is calculated in an RHF approximation using the 6–31G*basis set. The total energy of the molecule for its geometry optimization is calculated by the MP2 method including electron correlation. This leads to considerably improved agreement between the calculated coordination energy (25.3 kJ/mole) and the experimental value (28.5 kJ/mole). The geometry and the dipole moment calculated by both ab initio (HF/6-31G*//HF/6-31G*, MP2/6-31G*//MP2/6-31G*) methods and by the AMI method are in satisfactory agreement with the experimental data.