OMS, OM(η2-SO), and OM(η2-SO)(η2-O2S) Molecules (M = Ce, Th) with Chiral Structure: Matrix Infrared Spectra and Theoretical Calculations.

Infrared absorptions of the matrix isolated OMS, OM(η2-SO), and OM(η2-SO)(η2-O2S) (M = Ce, Th) molecules were observed following reactions of laser-ablated Ce and Th metal atoms with SO2 during condensation in excess argon and neon. Band assignments for the main vibrational modes were confirmed by appropriate 34SO2 and S18O2 isotopic shifts. B3LYP, BPW91 density functional, and CASSCF/CASPT2 calculations were performed to characterize these new reaction products and to explore the admixture of f orbitals into the bonding giving stronger M≡O triple bonds. It is very interesting that both OM(η2-SO) and OM(η2-SO)(η2-O2S) molecules show chiral structure.