REACTIONS OF 5)(MU-DPPM)PD](MU-SC6F5))(4)CENTER-DOT-2O(C2H5)(2) - CRYSTAL-STRUCTURES OF THE COMPLEXES -SC6F5)(MU-DPPM)PD(SC6F5)]CENTER-DOT-1.4CH(2)CL(2) AND F5)(MU-DPPM)PD(PPH3)]SO3CF3-CENTER-DOT-2CH(2)CL(2) AND AB-INITIO MO CALCULATIONS ON THE MODEL SYSTEMS 2PCH2PH2)(MU-SH)PD(PH3)](-H2PCH2PH2)PD(PH3)](2+)() AND [(H3P)PD(MU)

{[Pd(mu-SC6F5)(mu-dppm)Pd](mu-SC6F5)}(4) reacts 1:4 with neutral ligan ds L to give [LPd(mu-SC6F5)(mu-dppm)Pd(SC6F5)] or 1:8 to form [LPd(mu- SC6F5)(mu-dppm)PdL](+) (dppm = bis (diphenylphosphino)methane). These binuclear complexes retain the palladium-palladium bond and the two di ssimilar bridging ligands, as demonstrated by the X-ray structural det erminations carried out on [(Ph3P)Pd(mu-SC6F5)(mu-dppm)Pd(SC6F5)]. 1.4 CH(2)Cl(2) and [(Ph3P)Pd(mu-SC6F5)(mu-dppm)Pd(PPh3)]SO3CF3 . 2CH(2)Cl( 2). Ab initio calculations on the model systems [(H3P)Pd(mu-H2PCH2PH2) (mu-SH)Pd(PH3)](+) and [(H3P)Pd(mu-H2PCH2PH2)Pd(PH3)](2+) show that th e metal-metal bond arises mainly from interactions between palladium s p orbitals, which also play a predominant role in the binding with the sulfur bridge.