Terminal and bridged diphenyl phosphido complexes derived from niobocene and Group 6 metal carbonyls (Cr, Mo, W). Structures of Cp 2NB(L) (μ-PPH 2)Cr(CO) 5, S (L = CO, S = CH 3COCH 3; L = P (OMe) 3, S = C 6H 5CH 3)

Abstract

New terminal monophosphido complexes derived from bent niobocene Cp 2Nb(L)PPh 2 (L = P(OMe) 3, PMe 2H) have been prepared by a procedure described earlier for Cp 2Nb(CO)PPh 2. These metallophosphines have been used to bind the M(CO) 5 (M = Cr, Mo, W) fragments The expected dimetallic monobridged complexes of the type Cp 2Nb(L) (μ-PPh 2)M(CO) 5 (L = CO, P(OMe) 3, PMe 2H; M = Cr, Mo, W) are formed. When L = CO the dibridged compounds Cp 2Nb(μ-PPh 2) (μ-CO)M(CO) 4 (M = Cr, W) are also obtained. All new mono- and dimetallic complexes have been characterized by 1H and 31PNMR and IR spectroscopies. X-ray diffraction studies of solvated Cp 2Nb(CO) (μ-PPh 2)Cr(CO) 5 and Cp 2Nb(P(OMe) 3) (μ-PPh 2)Cr(CO) 5 indicated that the metallic centers in both complexes are thethered by a single bridge. The large Nb-P-Cr angles (125.94(8) and 129.11(5)▾, respectively) and the long Nb-Cr distances (4.653(1) and 4.7575(9) Å, respectively) clearly show the absence of metal-metal interaction.