CHEMISTRY OF VINYLIDENE COMPLEXES .11. SYNTHESIS OF TRINUCLEAR MNFEPTCOMPLEXES BY MEANS OF CONSECUTIVE ASSEMBLING OUT OF MONOMETAL AND DIMETAL VINYLIDENE PRECURSORS

The dimetal mu-vinylidene complexes Cp(CO)(2)MnPt(mu-C=CHPh)L(2) (L=te rt.-phosphine or -phosphite), which have been obtained by coupling of the mononuclear complex Cp(CO)(2)Mn=C=CHPh and unsaturated PtL(2) unit , add smoothly the Fe(CO)(4) moiety to produce trimetal MnFePt compoun ds. The mu(3)-vinylidene cluster CpMnFePt(mu(3)-C=CHPh)(CO)(6)(PPh(3)) was prepared in quantitative yields from the reactions of Cp(CO)(2)Mn Pt(mu-C=CHPh)(PPh(3))L (L=PPh(3) or CO) with Fe-2(CO)(9) in benzene at 20 degrees C. The phosphite-substituted complexes Cp(CO)(2)Mnpt(mu-C= CHph)L(2) (L=P(OEt)(3) or P(OPri)(3)) react under analogous conditions with Fe-2(CO)(9) to give mixtures (2:3) of the penta- and hexacarbony l clusters, CpMnFePt(mu(3)-C= CHPh)(CO)(5)L(2) and CpMnFePt(mu(3)-C=CH Ph)(CO)(6)L, respectively. The similar reaction of the dimetal complex Cp(CO)(2)MnPt(mu-C=CHPh)(dppm), in which the Pt atom is chelated by d ppm=Ph(2)PCH(2)PPh(2) ligand, gives only a 15% yield of the analogous trimetal mu(3)-vinylidene hexacarbonyl product CpMnFePt(mu(3)-C=CHPh)( CO)(6)(dppm), but the major product (40%) is the tetranuclear mu(4)-vi nylidene cluster (dppm)PtFe3(mu(4)-C=CHPh)(CO)(9). The IR and H-1, C-1 3 and P-31 NMR data for the new complexes are reported and discussed.