Pure rotational spectrum, ab initio anharmonic force field, and equilibrium structure of silyl chloride

The ground state rotational spectra of H₃Si³⁵Cl, H₃Si³⁷Cl, and D₃Si³⁵Cl have been measured from the microwave to the submillimeterwave ranges and accurate rotational parameters have been determined. For H₃Si³⁷Cl, they are in good agreement with the values obtained from the ground state combination differences. The quadratic, cubic, and semi-diagonal quartic force field has been calculated at the MP2 level of theory employing a basis set of polarized valence quadruple-zeta quality. This force field has been used to predict the spectroscopic constants. The calculated values are found to be in good agreement with the available experimental data. The equilibrium structure has been derived from the experimental ground state rotational constants and either the ab initio or the experimental rovibrational interaction parameters. These experimental and semi-experimental structures are in excellent agreement with the ab initio equilibrium geometry.