CO SUBSTITUTION AND DIPHOSPHINE LIGAND CHELATION IN THE REACTION BETWEEN S(DIPHENYLPHOSPHINO)-4-CYCLOPENTEN-1,3-DIONE(BPCD) AND RE-2(CO)(8)(MU-H)(MU-ETA(1),ETA(2)-C-CPH)

The reaction between the redox-active diphosphine ligand 4,5-bis(diphe nylphosphino)-4-cyclopenten-1,3-dione (bpcd) and the dirhenium compoun d Re-2(CO)(8)(mu-H) (mu-eta(1), eta(2)-C=CPh) in CH2Cl2 at room temper ature proceeds by CO loss to give the dirhenium complex Re-2(CO)(7)(bp cd)(mu-H)(eta(1)-C=CPh) (1). This new complex was characterized in sol ution by IR and NMR (H-1 and P-31) spectroscopy and in the solid state by X-ray diffraction analysis. Re-2(Co)(7)(bpcd)(mu-H)(eta(1)-C=CPh) crystallizes in the triclinic space group P (1) over bar: a = 11.3900( 9), b = 13.3921(9), c = 14.275(1) Angstrom, alpha = 84.280(6)degrees, beta = 89.678(6)degrees, gamma = 69.240(6)degrees, V = 2024.9(3) Angst rom(3), Z = 2, d(calc) = 1.862 g cm(-3), R = 0.0221, R(W) = 0.243 for 4066 observed reflections. The bpcd ligand in 1 adopts a chelating mod e with a linear phenylacetylide ligand being located on the adjacent r henium center cis to the bpcd ligand. This complex represents the firs t structurally characterized example of a hydride-bridged dirhenium co mplex possessing both a linear acetylide ligand and a chelating diphos phine ligand.