Syntheses and ligand interconversions of copper(II) derivatives of the metalloligand [Pt₂(µ-S)₂(PPh₃)₄]

Abstract

The reactivity of the metalloligand [Pt₂(µ-S)₂(PPh₃)₄] towards a variety of copper(II)–ligand systems has been studied. Reaction of [Pt₂(µ-S)₂(PPh₃)₄] with copper(II) halide complexes [CuCl₂L](L = 2,2 -bipyridine and 1,10-phenanthroline) gave trinuclear dicationic products [Pt₂(µ-S)₂(PPh₃)₄CuL]²⁺, and the 8-hydroxyquinolinate (hq) complex [Cu(hq)₂] gave [Pt₂(µ-S)₂(PPh₃)₄Cu(hq)]⁺, isolated as their BPh₄⁻ or PF₆⁻ salts. Related cationic complexes with other ancillary amine ligands (1,2-diaminoethane, 1,2-diaminopropane, 1,2-diaminocyclohexane) were obtained by reactions of [Pt₂(µ-S)₂(PPh₃)₄] with CuCl2 and the amine. In contrast, reaction of [Pt₂(µ-S)₂(PPh₃)₄] with CuCl₂ and NH₃ in methanol gave the intensely blue methoxy-bridged dicopper complex [{Pt₂(µ-S)₂(PPh₃)₄Cu(OMe)}₂]²⁺, isolated as its hexafluorophosphate salt. Copper β-diketonate complexes reacted with [Pt₂(µ-S)₂(PPh₃)₄] giving [Pt₂(µ-S)₂(PPh₃)₄Cu(β-diketonate)]⁺PF₆⁻ complexes, with the CH₃COCHCOCH₃(acac) and CF₃COCHCO(2-thienyl)(tta) derivatives characterised by X-ray structure determinations. The local Cu(II) environment ranges from distorted square-planar to an intermediate form of square-planar and tetrahedral. The β-diketonate derivatives show varying stability towards methanolysis, giving [{Pt₂(µ-S)₂(PPh₃)₄Cu(OMe)}₂]²⁺.