Formation of Pd2X2(mu-S)(mu-dpm)(2) by reaction of PdX2(dpm) with H2S in the presence of alumina (X = halogen, dpm = diphenylphosphinomethane)

Alumina promotes the reaction of PdX2(dpm) (3) (X = Cl, Br, I) with H2S to form Pd2X2(mu-S)(dpm)(2) (2)(1) and HX, with chemisorption of the HX (quant ified by titration) providing the driving force; although no intermediate s pecies are detected, the reaction likely proceeds via mercapto species form ed via 'alumina activated H2S'. XPS studies show interactions of species 2 and 3 with alumina, these interactions being weak as demonstrated by recove ry of the species on dissolution using an appropriate solvent. For the iodi de system, adsorbed HI on alumina undergoes partial photodecomposition to g ive I-2 and H atoms. (C) 1999 Elsevier Science B.V. All rights reserved.