HETEROBIMETALLIC DIBRIDGED COMPLEXES [CP(2)TA(MU-CO)(MU-PME(2))M'(CO)(4)] (M'=CR,W) - SYNTHESIS AND REACTIVITY TOWARD 2-ELECTRON DONOR LIGANDS L (L=PR(3), ME(2)P(CH2)(N)PME(2), CNR)

The heterobimetallic phosphido-bridged complexes Cp(2)Ta(CO)(mu-PMe(2))M'(CO)(5) (M' = Cr, Mo, W) (2a-c) were prepared by the reaction of the terminal phosphido complex Cp(2)Ta(CO)-(PMe(2)) with M'(CO)(5)(THF). Photolytic elimination of one CO from the monobridged complexes produced the dibridged compounds Cp(2)Ta(mu-Co)(mu-PMe(2))M'(CO)(4) (M' = Cr, W) (3a,b). Addition reactions between 3a and 3b and Lewis bases L (L = phosphines, diphosphines, isonitriles) lead to Cp(2)Ta(CO)(mu-PMe(2))M'(CO)(4)(L) (4a,b-10a,b, 11) with L regiospecifically coordinating to M'. Depending upon the nature of L and M', the reaction may be stereospecific, since the coordination oft can lead to cis or trans arrangements (with respect to the PMe(2) bridge) on the M' site. All new bimetallic complexes have been characterized by H-1 and P-31 NMR and IR spectroscopy and elemental analyses.