CARBON-DIOXIDE INSERTION INTO THE FE-ZR AND RU-ZR BONDS OF THE HETEROBIMETALLIC COMPLEXES CP(CO)2M-ZR(CL)CP2 - DIRECT PRODUCTION OF THE MU-ETA(1)(C)ETA(2)(O,O')-CO2 COMPOUNDS CP(CO)2M-CO2-ZR(CL)CP2

The Fe-Zr and Ru-Zr heterobimetallic compounds Cp(CO)2M-Zr(Cl)CP2 inco rporate carbon dioxide under mild conditions and give their respective mu-eta1(C): eta2(O,O') bimetallocarboxylates Cp(CO)2M-CO2-Zr(Cl)Cp2. With Cp(CO)2Fe-Zr(Cl)Cp2,1 equiv of CO2 or (CO2)-C-13 (99% labeled) qu antitatively adds at above 0-degrees-C in THF. The resulting CO2 adduc t, Cp(CO)2Fe-CO2-Zr(Cl)CP2, was independently synthesized and fully ch aracterized. Cp(CO)2Fe-(CO2)-C-13-Zr(Cl)Cp2 equilibrates with its isot opomer Cp((CO)-C-13)(CO)Fe-CO2-Zr(Cl)CP2 at room temperature. Results of control experiments preclude ionization of Cp(CO)2Fe-Zr(Cl)CP2 to C P(CO)2Fe-/+(THF)Zr(Cl)Cp2 in order to add CO2. Operation of a CO2 inse rtion pathway that requires bifunctional activation of the CO2 is disc ussed. Analogous Ru-Zr CO2 insertion chemistry requires more forcing c onditions: 3-5 atm of CO2 and 3 days.