Ab-initio study of OCCS, OCCS+ and related species

Calculations on OCCS and OCCS+ are reported at the G1, G2, G2(MP2) and CCSD(T) levels of theory. Optimised geometric parameters, ionisation potentials, enthalpies of formation and dissociation energies have been calculated. The results are compared with those for OCCO and SCCS species. CCSD(T)/aug-cc-pvtz energies give better agreement with experimental energies than do the G2 energies. The calculated ionisation potential of OCCO suggests that the (CO)2 species observed experimentally is not OCCO.