HETEROPOLYNUCLEAR SYSTEMS - SYNTHESIS OF BIMETALLIC AND TRIMETALLIC COMPLEXES INVOLVING BIS(ETA(5)-CYCLOPENTADIENYL)TUNGSTEN DERIVATIVES

A new convenient route to a series of heteropolymetallic complexes has been developed in which mono- and dichloro tungstenocene complexes re act with [PPh2M(CO)(5)]Li salts (with M = Cr, W). When monohydride mon ochloride compounds (eta(5)-C5H5)[eta(5)-C5H4PPh2M(CO)(5)]W(H)Cl, 1, a re used as starting metallocenes, a substitution reaction takes place at the metal center and heterotrimetallics 5)-C5H5)[eta(5)-C5H4PPh2M(C O)(5)]W(H)[PPh2M(C)(5), 2, are obtained; in contrast, using dichloride compounds (eta(5)-C5H5)[eta(5)-C5H4PPh2M(CO)(5)]WCl2, 3, trinuclear c omplexes [eta(5)-C5H4PPh2M(CO)(5)](2)W(H)(Cl), 4, are isolated, in whi ch both of the cyclopentadienyl groups are substituted. The reactivity of the intramolecular hydride-bridged complex (eta(5)-C5H5)[eta(5)-C5 H4PPh2Cr(CO)(4)]W(mu-H)(H), 8a, towards Lewis bases has also been stud ied; the reaction of 8a with PMe3 (or PMe2Ph) affords a mixture of the two trans and cis isomers 9a+9'a (or 10a+10'a). Addition of the metal lophosphine Cp2Nb(CO)(PMe2) does not lead to the expected heterotrinuc lear complex, but yields the phosphido mononuclear tungsten complex (e ta(5)-C5H5)[eta(5)-C5H4PPh2]WH2, 11a. The X-ray structure of 4a is rep orted.