The title compound was prepared upon irradiation of acetonitrile solutions of the readily available hexacarbonyl [MoReCp(mu-H) (mu-PCy2) (CO)(6)]. The acetonitrile ligand in this compound could be replaced easily by donor molecules or displaced upon two-electron reduction. In most cases, the substitution step was followed by additional processes such as insertion into the M-H bonds, E-H bond cleavage, H-2 elimination, and other transformations.