CO Substitution and Cluster-Ligand Reductive Coupling in the Reaction of 2,3-Bis(diphenylphosphino)maleic Anhydride (bma) with the Mixed-metal Clusters PhCCo2MCp(CO)8 (where M = Cr, W): Synthesis and X-ray Diffraction Structures of the Phosphido-bridged Clusters Co2MCp(CO)5[μ2,η2,η1-C(Ph)C=C(PPh2)C(O)OC(O)](μ-PPh2)

摘要

The ligand substitution behavior of the mixed-metal tetrahedrane clusters PhCCo2MCp(CO)8 [where M = Cr (1), W (3)] with the diphosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) has been examined, and the phosphido-bridged clusters Co2MCp(CO)5[μ2,η2,η1-C(Ph)C=C(PPh2)C(O)OC(O)](μ-PPh2) [where M = Cr (2), W (4)] have been confirmed as the principal reaction products. Both 2 and 4 have been isolated and characterized in solution by IR and 31P NMR spectroscopies, and the molecular structures established by X-ray diffraction analyses. Clusters 2 and 4 each contain 48e? and exhibit triangular Co2M cores that are bridged by a phosphido moiety across the M–Co bond and face-capped by a six-electron μ2,η2,η1-C(Ph)C=C(PPh2)C(O)OC(O) ligand. The reactivity of clusters 1 and 3 with bma is contrasted to the corresponding molybdenum clusters PhCCo2MoCp(CO)8 and PhCCo2Mo(indenyl)(CO)8 previously investigated by our groups.