Terminal and bridged diphenyl phosphido complexes derived from nioboceneand Group 6 metal carbonyls (Cr, Mo, W). Structures of Cp2Nb(L)(μ-PP h2)Cr(CO)5, S (L=CO, S=CH3COCH3; L=P(OMe)3, S=C6H5CH3)

Article abstract of DOI:10.1016/0020-1693(95)04667-X

New terminal monophosphido complexes derived from bent niobocene Cp2Nb(L)PPh2(L=P(OMe)3, PMe2H) have been prepared by a procedure described aerlier for Cp2Nb(CO)PPh2. These metallophosphines have been used to bind the M(CO)5 (M = Cr, Mo, W) fragments. The expected dimetallic monobridged complexes of the type Cp2Nb(L)(μPPh2)M(CO)5 (L=CO, P(OMe)3, PMe2H; M = Cr, Mo, W) are formed. When L=CO the dibridged compounds Cp2Nb(μ-PPh2)(μ-CO)M(CO)4 (M = Cr, W) are also obtained. All new mono- and dimetallic complexes have been characterized by (1)H and (31)P NMR and IR spectroscopies. X-ray diffraction studies of solvated Cp2Nb(CO)(μ-PPh2)Cr(CO)5 and Cp2Nb(P(OMe)3)(μ-PPh2)Cr(CO)5 indicate that the metallic centers in both complexes are tethered by a single bridge. The large Nb-P-Cr angles (125.94(8) and 129.11(5)°, respectively) and the longNb-Cr distances (4.653(1) and 4.7575(9)?, respectively) clearly sho w the absence of metal-metal interaction.