Thermal reactivity of Group 9 transition metal pinacolate complexes: heterocumulene cleavage and CO bond formation

The reactions of Group 9 transition metal pinacolate complexes Cp*M(pin) (M=Co (1), Rh (2), Ir (3)) with heterocumulenes (YCZ) are described. In these transformations the CZ bond of the heterocumulene is cleaved, and the pinacolate ligand is incorporated into an organic heterocycle (pin)CY. In some cases a clean organometallic product of the general formula Cp*MZ2CY is also produced. The regiochemistry of these reactions has been explored and found to follow expected trends, and evidence suggests a mechanism involving initial heterocumulene insertion into an MO bond yielding a 7-membered metallacycle, followed by 1,2 elimination.