Ab initio

Minimum-energy geometries, harmonic vibrational frequencies, and relative electronic energies of some low-lying singlet and triplet electronic states of stannous dichloride, SnCl2, have been computed employing the complete-active-space self-consistent-field/multireference configuration interaction (CASSCF/MRCI) and/or restricted-spin coupled-cluster single-double plus perturbative triple excitations [RCCSD(T)] methods. The small core relativistic effective core potential, ECP28MDF, was used for Sn in these calculations, together with valence basis sets of up to augmented correlation-consistent polarized-valence quintuple-zeta (aug-cc-pV5Z) quality. Effects of outer core electron correlation on computed geometrical parameters have been investigated, and contributions of off-diagonal spin-orbit interaction to relative electronic energies have been calculated. In addition, RCCSD(T) or CASSCF/MRCI potential energy functions of the 1A1, ã 3B1, and 1B1 states of SnCl2 have been computed and used to calculate anharmonic vibrational wave functions of these three electronic states. Franck-Condon factors between the 1A1 state, and the ã 3B1 and 1B1 states of SnCl2, which include anharmonicity and Duschinsky rotation, were then computed, and used to simulate the ã- and - absorption and corresponding single-vibronic-level emission spectra of SnCl2 which are yet to be recorded. It is anticipated that these simulated spectra will assist spectroscopic identification of gaseous SnCl2 in the laboratory and/or will be valuable in in situ monitoring of SnCl2 in the chemical vapor deposition of SnO2 thin films in the semiconductor gas sensor industry by laser induced fluorescence and/or ultraviolet absorption spectroscopy, when a chloride-containing tin compound, such as tin dichloride or dimethyldichlorotin, is used as the tin precursor