Infrared absorptions of the matrix isolated OMS, OM(eta(2)-SO), and OM(eta(2)-SO)(eta(2)-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 (SO2)-S-34 and (SO2)-O-18 isotopic shifts. B3LYP, BPW91 density functional, and CASSCF/CASPT2 calculations were performed to characterize these new reaction products and to explore the admixture off orbitals into the bonding giving stronger M (math)O triple bonds. It is very interesting that both OM(eta(2)-SO) and OM(eta(2)-SO)(eta(2)-O2S) molecules show chiral structure.