Reaction of pentacarbonyl-manganese(-I) and -rhenium(-I) with metal carbonyl halide derivatives

Studies are reported related to the reaction of M(CO)₅^- (M = Mn, Re) with XM(CO)₃L, XM(CO)₅, and XRe(CO)₃(pyridine)₂ (X = Cl, Br, I; M = Mn, Re; L = 2,2′-bipyridine, 1,10-phenanthroline, 1,2-bis(diphenylphosphino)ethane, 2,2′-biquinoline, 4,7-diphenyl-1,10-phenanthroline, o-phenylenebis(dimethylarsine), and cis-1,2-bis(diphenylphosphino)ethylene) which may yield metalmetal bonded complexes. Neither XM(CO)₅ nor XRe(CO)₃(pyridine)₂ react at 25°C, and for XM(CO)₃L only those complexes which are easily reduced (L = 2,2′-bipyridine, 1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, and 2,2′-biquinoline) readily yield products of the formula M₂(CO)₈L. The data suggest that the metalmetal bond formation is not via a simple nucleophilic attack mechanism but likely involves prior electron transfer to generate XM(CO)₃L^-.