Metal complexes of sulphur ligands. Part 22. Reaction of platinum(II) and palladium(II)NN-dialkyldithiocarbamates with diphenylphosphine chalcogenides

Abstract

Reaction of [Pt(S₂CNR₂)₂](R = Et or Prⁱ) with either Ph₂P(O)H or prehydrolysed Ph₂PCl in alcohols give high yields of [Pt(S₂CNR₂){(Ph₂PO)₂H}](1). In contrast, reaction of [Pt(S₂CNR₂)₂] with Ph₂P(S)H in alcohols give a variety of products, depending on the amount of sulphide used, the amount of water present in the reaction mixture, and the duration of reaction. Thus with an excess of Ph₂P(S)H in dry methanol, [NR₂H₂][Pt(S₂CNR₂)(Ph₂PS)₂](2) are formed and the structure of (2a)(R = Et) has been verified by X-ray analysis. The crystals are orthorhombic, space group P2₁2₁2₁ with a= 21.098(18), b= 11.679(8), c= 14.816(18)Å. Prolonged reaction in dry methanol gives [Pt(S₂CNR₂){Ph₂P(OMe)}(Ph₂PS)](5) whereas with 1 : 1 mol ratios of Pt : Ph₂P(S)H, small amounts of the binuclear [{ Pt(S₂CNEt₂)(Ph₂PS)}₂](6a) are formed. These are obtained in much higher yield by reaction of compound (2) with HCl gas in dry CHCl₃ and the structure of (6b)(R = Prⁱ) confirmed by X-ray analysis. The crystals are monoclinic, space group P2₁/c with a= 12.192(7), b= 9.272(6), c= 24.958(15)Å, and β= 116.232(28)°. Small amounts of the secondary phosphine complexes [Pt(S₂CNR₂)(Ph₂PH)(Ph₂PS)](4) are also formed in all these reactions and these can be synthesised in high yield by direct reaction of compound (2) with Ph₂PH. Finally, in wet methanol, the neutral complexes [Pt(S₂CNR₂)(Ph₂POHSPPh₂)](3) are formed together with some of compound (2). The corresponding reaction of [Pd(S₂CNEt₂)₂] with an excess of Ph₂P(S)H in dry methanol gives [NEt₂H₂][Pd(S₂NEt₂)(Ph₂PS)₂] and [{Pd(S₂CNEt₂)(Ph₂PS)}₂] whereas the reaction of [Pt(S₂CNR₂)₂] with Ph₂P(Se)H gives only [Pt(S₂CNR₂)(Ph₂PH)(Ph₂PSe)] in high yield. All these compounds have been characterised by a variety of physicochemical methods and a reaction scheme to account for the formation of compounds (2)–(6) from reaction of [Pt(S₂CNR₂)₂] with Ph₂P(S)H is suggested.