Transformation of carbon dioxide to methoxide by the complex [(C5H(5))Ti](2)(mu-H)(2)(mu-C10H8)

Hydrogenation of carbon dioxide by the complex (CpTi)(2)(mu -H)(2)(mu -C10H 8) (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 H-2, CO2, H2O, M eOH, and (CpTi)(2)(mu -Cl)(2)(mu -C10H8). The amount of H-2 formed reveals that one of the two bridging hydrides reacts with CO2. The unreacted bridgi ng hydride becomes a terminal hydride, as indicated by infrared spectroscop y. Carbon dioxide released during protonation stems from the complexes form ed between CO2 and reaction products. Protonation also converts the oxo lig and originated from CO2 to H2O. The labeling study with DCl in D2O yields D OCH3, indicating that the complex 1 transforms CO2 to methoxide, not formal dehyde. (C) 2000 Elsevier Science B.V. All rights reserved.