DIBRIDGED BIMETALLIC COMPLEXES DERIVED FROM BENT NIOBOCENE AND GROUP 6 METAL CARBONYLS - TRANSMETALLATION OF THE PME(2)H LIGAND AND CRYSTAL STRUCTURE OF CP(2)NB(MU-PPH(2))(MU-CO)CR(CO)(3)(PME(2)H)

摘要

The bimetallics Cp(2)Nb(mu-PPh(2))(mu-CO)M(CO)(3)(PMe(2)H) (M = Cr, W) were prepared by UV irradiation of the dinuclear monobridged complexes Cp(2)Nb(PMe(2)H)(mu-PPh(2))M(CO)(5). These compounds may also be obtained in good yield directly from metallophosphine Cp(2)Nb(PPh(2))(PMe(2)H) and Cr(CO)(4)(eta(4)-norbomadiene) or W(CO)(4)(piperidine)(2). Their formations are accompanied by the transfer of the PMe(2)H ligand from Nb to M (M=Cr, W). The Nb-Cr distance of 3.02(1) Angstrom observed in the structure of Cp(2)Nb(mu-PPh(2))(mu-CO)Cr(CO)(3)(PMe(2)H) indicates the presence of a direct metal-metal bond and agrees with the P-31 NMR data. [References: 10]