LEWIS-ACID CATALYSIS OF THE REARRANGEMENT OF A DIPALLADIUM ACETYLENE ADDUCT TO A VINYLIDENE-BRIDGED COMPLEX

The crystallographically characterized vinylidene complex [Pd2Cl2(mu-d ppm)(2)(mu-sigma-C=C-(SCH3)(2))] (3); dppm = bis(diphenylphosphino)met hane) was prepared by the reaction of [Pd2Cl2(mu-dppm)(2)] with CH3SC drop CSCH3 in the presence of HBF4 . Et(2)O as well as through an isom erization of the acetylene adduct [Pd2Cl2(mu-dppm)(2)(mu-CH3SCCSCH3)] (1) catalyzed by several Lewis acids. Treatment of the related acetyle ne adduct [Pd2Cl2(mu-dmpm)(2)(mu-CH3SCCSCH3)] (2; dmpm = bis(dimethylp hosphino)methane) with HBF4 . Et(2)O yielded the tetranuclear palladiu m complex [Pd-4(mu-Cl)(2)(mu-dmpm)(2)(mu-SCH3)(4)][BF4](2) (4), which was also characterized crystallographically.