CO 2 cleavage by tantalum/M (M = iridium, osmium) heterobimetallic complexes.

A novel Ta/Os heterobimetallic complex, [Ta(CH 2 t Bu) 3 (μ-H) 3 OsCp*], 2, is prepared by protonolysis of Ta(CH t Bu)(CH 2 t Bu) 3 with Cp*OsH 5 . Treatment of 2 and its iridium analogue [Ta(CH 2 t Bu) 3 (μ-H) 2 IrCp*], 1, with CO 2 under mild conditions reveal the efficient cleavage of CO 2 , driven by the formation of a tantalum oxo species in conjunction with CO transfer to the osmium or iridium fragments, to form Cp*Ir(CO)H 2 and Cp*Os(CO)H 3 , respectively. This bimetallic reactivity diverges from more classical CO 2 insertion into metal-X (X = metal, hydride, alkyl) bonds.