BRIDGED DERIVATIVES OF THE HETERONUCLEAR CARBONYL-COMPLEXES [COM(CO)9] (M = MN,RE)

The new heterobinuclear complexes [CoM(CO)5(mu-dppm)2], 1, and [CoM(CO)6(mu-dppm)(eta1-dppm)], 2, where M = Mn or Re and dppm = Ph2PCH2PPh2, have been prepared by reaction of [COX(CO)2(eta1-dppm)2], X = halogen, with Na[M(CO)5]. Complexes 1 and 2 have been characterized by spectroscopic methods and, for 1a (M = Mn), by an X-ray structure determination. The nature of the fluxionality of the carbonyl ligands in la has also been studied; at room temperature, a merry-go-round mechanism leads to equivalence of all carbonyl ligands.