Theoretical study of the interaction of the Ti atom with CO2: Cleavage of the C-O bond

The interaction of s(2)d(2) and s(1)d(3) Ti atoms with the CO2 molecule has been studied using density functional theory at the gradient-corrected level. The ground state Ti inserts with no energy barrier into a CO bond resulting in an OTiCO insertion product. The intrinsic reaction coordinate for the insertion process has been defined and the reaction mechanism has been investigated by analyzing various structures along this path. The singlet and triplet states of the final product are very close in energy. The comparison of the predicted vibrational frequencies and isotopic shifts for both states with those from matrix isolation infrared data reveals that the insertion product formed in low-temperature argon matrix corresponds to singlet state OTiCO. Ti(CO2) complexes in various coordination modes have also been located on the triplet and quintet potential energy surfaces, from which the triplet state (0,0) coordination mode is the most stable one lying, however, about 30 kcal/mol above the OTiCO molecule.