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⁺.