THEORETICAL PREDICTION OF THE VIBRATIONAL-SPECTRUM, GEOMETRY, AND SCALED QUANTUM-MECHANICAL (SQM) FORCE-FIELD OF PHENYLSILANE, C6H5SIH3

The optimized geometry and the complete harmonic force field of phenyl silane were determined by using ab initio Hartree-Fock calculations an d the 4-21 gaussian basis set. To remove the systematic deficiencies w hich arise from the use of a finite basis set and neglect of electron correlation and anharmonicity, a set of scaling factors previously opt imized for toluene was applied to obtain the final scaled quantum mech anical (SQM) force field. Frequencies calculated from the SQM force fi eld of phenylsilane confirm most of the previous experimental assignme nts for the infrared and Raman spectra. There are, however, a number o f interesting discrepancies which point to alternative band assignment s. Theoretical infrared intensities reproduce the main features of the spectrum with sufficient accuracy to be helpful in the assignment.