REACTION OF BIS (DIMETHOXYPHOSPHINO)DIMETHYLHYDRAZINE (DMPDMH) WITH PHCCO3(CO)(9) - SYNTHESIS AND X-RAY CHARACTERIZATION OF THE DMPDMH-BRIDGED POLYMORPHS OF PHCCO3(CO)(7)[(MEO)(2)PN(ME)N(ME)P(OME)(2)]

The tricobalt cluster PhCCo3(CO)(9) reacts with the bis(phosphanyl)hyd razine ligand bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) to giv e the monosubstituted cluster [PhCCo3-(CO)(8)](2)(dmpdmh) and the disu bstituted cluster PhCCo3(CO)(7)(dmpdmh) as the major products. This la tter cluster contains a bridging dmpdmh ligand. Both IR and NMR spectr oscopies (P-31 and H-1) have been employed in the solution characteriz ation of these two clusters. The solid-state structure of PhCCo3(CO)(7 )(dmpdmh) was unequivocally established by X-ray diffraction analysis, which has revealed the presence of two different polymorphs for this particular cluster. The first polymorph crystallizes in the monoclinic space group P2(1)/n, a = 9.7127(7) Angstrom, b = 17.025(2) Angstrom, c = 16.894(1) Angstrom, beta = 96.245(5)degrees, V = 2777.0(4) Angstro m(3), Z = 4, and d(calc) = 1.689 g/cm(3); while the second polymorph c rystallizes in the orthorhombic space group Pbca, a = 16.925(2) Angstr om, b = 16.208(2) Angstrom, c = 20.541(3) Angstrom, V = 5635(1) Angstr om(3), Z = 8, and d(calc) = 1.665 g/cm(3).