Analysis of the Rotational Spectra of SiH3CN and Its Isotopomers: Experimental and Ab Initio Determinations of the Dipole Moment and the Structure.

The ground state rotational spectra of SiH3CN and its 29Si, 30Si, 13C, 15N, d1, d2, and d3 isotopic species have been measured by Fourier transform microwave spectroscopy and by millimeterwave spectroscopy. Accurate rotational, centrifugal distortion, and 14N and D nuclear quadrupole coupling constants have been derived. The dipole moment of the parent species has also been measured, µ = 3.4400(42) D. The structure, force field, dipole moment, and nuclear quadrupole coupling constants have been calculated ab initio at the SCF, MP2, and B3LYP levels using triple zeta polarized basis sets. The experimental ro, rs, and rz structures have been determined. An approximate equilibrium structure has been obtained by combining the experimental results and the ab initio calculations: re(C&tbond;N) = 1.159 Å, re(Si&sbond;C) = 1.848 Å, re(Si&sbond;H) = 1.470 Å, and angle(HSiC) = 107.4 degrees. Copyright 1998 Academic Press.