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

Although palladium phosphine acetates are generally unstable and served as catalytic precursors, their monothioacetate analogues can be isolated and s tructurally characterized. Spectroscopic and X-ray single-crystal crystallo graphic analyses suggested that Pd(KS-S{O}CMe)(2)(P-2) [P-2 = dppf I; P = P Ph3 II] are mononuclear with thioacetate coordinates in a unidentate manner through sulfur. Dppf imposes a cis configuration on I whereas PPh3 promote s a trans-structure for II. The compounds are obtained in isomerically pure form-there is no evidence for chelating or bridging thioacetate or bridgin g diphosphine. The Me group of thioacetate is significantly more shielded i n II than I by the Ph rings of the neighboring phosphine. (C) 2001 Elsevier Science B.V. All rights reserved.