CLEAVAGE OF BIS(THIOPHOSPHINYL)DISULFANES, R(2)P(S)SSP(S)R(2) (R=ET, PH), BY A LOW-VALENT PALLADIUM DIMER

The reaction of Pd-2(mu-dcpe)(2) (dcpe = 1,2-bis(dicyclohexylphosphino )ethane) with the bis(thiophosphinyl)disulfanes, R(2)P(S)SSP(S)PR(2) ( R = Et, Ph), give the ionic complexes [(dcpe)Pd(SPR(2)S)](+)[SPR(2)S]( -) in 60% (1; R = Et) and 72% (2; R = Ph) yields. An unusual dimer, {( Et(2)PS(2))Pd}(2)(mu-Et(2)PS(2))(2), is also isolated in low yield for R = Et. The X-ray structure of a benzene solvate of 1 (C50H68P4S4Pd . 1.5C(6)H(6); monoclinic, a = 14.628(1) Angstrom, b = 16.662(3) Angstr om, c = 21.612(4) Angstrom, beta = 107.66(1), P2(1)/n, Z = 4, R = 0.04 7(F-0), R(w) = 0.056(F-0)) shows a nearly planar spirocyclic palladium atom in the cation and a free SPR(2)S(-) anion, Variable-temperature P-31 NMR spectra of 1 indicate rapid interchange of the coordinated an d free SPR(2)S(-) counterion in solution at room temperature.