Water soluble platinum(II) and palladium(II) complexes of alkyl sulfonatedphosphines

The reactions of the alkylsulfonated phosphines LM = Ph2P(CH2)(n)SO3Na/K (n = 2, 3, 4) with K2PtCl4 and K2PdCl4 have been studied in homogeneous aqueo us solution as a function of pH. In homogeneous acidic solution the protona ted phosphines react to give cis- and trans-PtCl2(LH)(2). The biphasic reac tion between 1,5-cyclooctadiene platinum(II) chloride in dichloromethane an d acidified aqueous LNa/K gives a higher proportion of the cis isomer. In n eutral solution the initial reaction to give [PtCl(LNa/K)(3)](+) Cl- is fol lowed by slow formation of cis-PtCl2(LNa/K)(2). K2PdCl4 reacts more rapidly to give PdCl2(LNa/K)(2). In homogeneous alkaline solution rapid oxidation of the phosphine occurs with only small amounts of platinum complex being o bservable. The biphasic reaction yields phosphine oxide in the aqueous laye r and a small amount of the chelate complexes PtL2 in the organic. Represen tative complexes have been isolated and characterised and the mechanisms fo r the reactions discussed. The electrospray mass spectra of solutions of th e isolated complexes have been recorded in both positive and negative ionis ation modes. The positive ionisation spectra are complicated, but platinum and palladium containing ions derived from loss of chloride, H+ and HCl are observed in the negative ionisation spectra. (C) 1999 Elsevier Science S.A . All rights reserved.