Palladium(II) phosphine thiocarboxylates. Structures of cis-Pd(κS-SOCMe)2(dppf) [dppf=1,1′-bis(diphenylphosphino)ferrocene] and trans-Pd(κS-SOCMe)2(PPh3)2

Although palladium phosphine acetates are generally unstable and served as catalytic precursors, their monothioacetate analogues can be isolated and structurally characterized. Spectroscopic and X-ray single-crystal crystallographic analyses suggested that Pd(κS-S{O}CMe)2(P2) [P2=dppf, I; P=PPh3, II] are mononuclear with thioacetate coordinates in a unidentate manner through sulfur. Dppf imposes a cis configuration on I whereas PPh3 promotes a trans-structure for II. The compounds are obtained in isomerically pure form—there is no evidence for chelating or bridging thioacetate or bridging diphosphine. The Me group of thioacetate is significantly more shielded in II than I by the Ph rings of the neighboring phosphine.