Ab initio quartic force field of stannane and rotational analysis of the ν1 infrared band of H120SnD3

Stannane, SnH4, has been studied both theoretically, using high-level ab initio methods, and experimentally, using high-resolution spectroscopy to analyze the Sn-H stretching fundamental band of the (HSnD3)-Sn-120 isotopologue. The geometry and the anharmonic force field of the molecule have been calculated ab initio, using the coupled-cluster with single, double, and perturbative triple excitations level of theory. (HSnD3)-Sn-120, present as minor isotopologue in (SnD4)-Sn-120, has been studied by Fourier transform spectroscopy at an effective resolution of ca. 0.005 cm(-1) near 1900 cm(-1) and the nu(1) band was identified. About 360 ro-vibration transitions with J' up to 18 and K up to 10 have been assigned. Since the spectrum evidenced the existence of some perturbations, the transitions were analyzed either neglecting, or including in the model A(1)/E Coriolis-type interactions with nearby dark states. The standard deviation of the fits, ca. 1.5 x 10(-3) cm(-1), is about one order of magnitude larger than the estimated experimental precision, and is only slightly dependent on the adopted model. The spectroscopic parameters obtained from this and from previous analyses of stannane isotopologues have been compared with the theoretical results. The theoretical force field is also used to obtain semi-experimental harmonic frequencies and the equilibrium geometry.