Transformation of carbon dioxide to methoxide by the complex [(C5H5)Ti]2(μ-H)2(μ-C10H8)

Hydrogenation of carbon dioxide by the complex (CpTi)2(μ-H)2(μ-C10H8) (1), in a ratio of 1.5 to 1, affords a mixture of products. Reaction of the product mixture with 2 equiv. of HCl in THF results in H2, CO2, H2O, MeOH, and (CpTi)2(μ-Cl)2(μ-C10H8). The amount of H2 formed reveals that one of the two bridging hydrides reacts with CO2. The unreacted bridging hydride becomes a terminal hydride, as indicated by infrared spectroscopy. Carbon dioxide released during protonation stems from the complexes formed between CO2 and reaction products. Protonation also converts the oxo ligand originated from CO2 to H2O. The labeling study with DCl in D2O yields DOCH3, indicating that the complex 1 transforms CO2 to methoxide, not formaldehyde.