Synthesis and spectroscopic properties of some new bi-, tri- and tetrametallic complexes of the type [M(CO)(5)L], [M(CO)(4)L-2] and [M(CO)(3)L-3] {M=Cr, Mo, W; L=[(WI2(CO){Ph2P(CH2)(2)P)over-bar-Ph(CH2)(2)PPh2-P,P'}(eta(2)-RC2R')] (R=R'=Me, Ph; R=Me, R'=Ph)}

Reaction of L {L=[WI2(CO){Ph2P(CH2)(2)PPh(CH2)(2)PPh2-P,P}(eta(2)-RC2R')] (R=R'=Me, Ph; R=Me, R'=Ph)} with an equimolar quantity of [M(CO)(5)(NCMe)] (M=Cr, Mo, W) (prepared in situ) gives high yields of the bimetallic complexes [M(CO)(5)L] {L=[WI2(CO){Ph2P(CH2)(2)PPh(Ch(2))(2)PPh2-P,P')(eta(2)-RC2R')] (M=Cr, W, R = R' = Me; M = Cr, Mo, R = Me, R' = Ph; M = Mo, W; R = R' R = ph)} (1--6). Treatment of cis-[M(CO)(4)(piperidine)(2)] (M = Mo, W) with two equivalents of L (as above) in refluxing Ch(2)Cl(2) affords the trimetallic complexes [M(CO)(4)L-2] {L = [WI2(CO){Ph2P(CH2)(2)PPh2-PP}(eta(2)-RC2R')] (M = Mo, W, R = R' = Me; M = W, R = Me, R' = Ph)} (7-->9). The cis-trans isomerism of complexes 7 and 8 has been investigated by infrared spectroscopy. Reaction of fac-[Mo(CO)(3)(NCMe)(3) (prepared in situ) with three equivalents of L in reflxing acetonitrile yields the tetrametallic complexes [Mo(C)(3)L-3{L=[WI2(CO){Ph2P(CH)(2)PPh(CH2)(2)PPh2-P,P'}(eta(2)-RC2R')](R = R'= Me, Ph; Me, R' = Ph)} (10-->12). All the new complexes have been characterised by elemental analysis (C, H and N), infrared H-1 NMR spectroscopy and in selected cases by P-31 NMR spectroscopy. (C) 1997 Elsevier Science S.A.