Extending knowledge on the nucleophilicity of the {Pt2S2} core: Ph2PCH2CH2PPh2 as an alternative terminal ligand in [L2Pt(µ-S)2PtL2] metalloligands†

Abstract

The reaction of [Pt₂(dppe)₂(µ-S)₂] 1, with metal complexes or metal salts gave different types of complexes depending on the nature of the heterometal and of the stoichiometric ratios employed. Thus, a trinuclear complex of formula [Pt(dppe){Pt₂(dppe)₂(µ₃-S)₂}]Cl₂ 2 and an apparently mixed Pd_xPt_3-x product 3 have been prepared and characterised. Alternatively, dissolution of 1 in chlorinated solvents affords 2 easily and 3 is formed from 1 with [PdCl₂(dppe)]. The pentanuclear complexes of formula [M{Pt₂(dppe)₂(µ₃-S)₂}₂]X₂ (M = Zn 4 or Cd 5, X = ClO₄; M = Cd, X₂ = [CdCl₄] 5′; M = Hg, X₂ = [PF₆][HgCl₄]_0.5 6) have been obtained. The structures of complexes 2, 3, 4, 5, 5′ and 6 have been determined crystallographically. Complex 2 comprises three slightly distorted square-planar cis-PtP₂S₂ co-ordination planes sharing two µ₃-S ligands. X-Ray data and NMR studies in solution of different crops of crystals support that 3 is essentially a simple solid-solution mixture of pure complexes [Pd(dppe){Pt₂(dppe)₂(µ₃-S)₂}][BPh₄]₂ 3′ and [Pt(dppe){Pd₂(dppe)₂(µ₃-S)₂}][BPh₄]₂ 3″ in variable proportions with at most a minor component of the homometallic complex 2. The structure of the cations of complexes 4, 5, 5′ and 6 comprises two {Pt₂S₂} butterflies linked through sulfur to the metal(II) ion, which shows a significantly distorted tetrahedral environment. All complexes have been fully characterised by multinuclear NMR techniques and the corresponding parameters are reported.