Formation and Subsequent Reactivity of a N2‑Stabilized Cobalt–Hydride Complex

The reduced heterobimetallic Co/Zr complex N2Co­( i Pr2PNMes)3Zr­(THF) (1) has been previously reported to react with the CO bonds of CO2 and benzophenone to generate Zr/Co μ-oxo complexes OC-Co­( i Pr2PNMes)2(μ-O)­Zr­( i Pr2PNMes) (1-CO 2 ) and Ph2CCo­( i Pr2PNMes)2(μ-O)­Zr­( i Pr2PNMes) (1-Ph 2 CO), respectively. Herein, we report a similar reaction of 1 with pyridine-N-oxide to form an analogous complex (pyridine)­Co­( i Pr2PNMes)2(μ-O)­Zr­( i Pr2PNMes) (2) with a more labile ligand bound to cobalt. Much like 1-CO 2 and 1-Ph 2 CO, compound 2 reacts with Ph3SiH via formation of a Si–O linkage to form (N2)­(H)­Co­( i Pr2PNMes)3ZrOSiPh3 (5). The dinitrogen ligand in 5 is weakly bound and can be readily removed in vacuo or displaced by other L-type ligands. This allows complex 5 to undergo insertion reactions with unsaturated substrates, including diphenyldiazomethane, CO2, benzonitrile, and phenylacetylene to give hydrazonato (Ph2CNNH)­Co­( i Pr2PNMes) 3 ZrOSiPh3 (7), formate (OC­(H)­O)­Co­( i Pr2PNMes)3ZrOSiPh3 (8), ketimide (PhHCN)­Co­( i Pr2PNMes)3ZrOSiPh3 (9), and ylide Co­(PhHCCHP i Pr2NMes)­( i Pr2PNMes)2ZrOSiPh3 (10) products, respectively. Compound 5 was also found to catalyze the isomerization of 1-hexene to internal isomers.