Mixed Valence Pt(II),Pt(IV),Pt(II) Complexes from a Diplatinum(III) Synthon and Sulfur-Based Anions

The coordination of the S-based anions, thiophenoxide (PhS^–, a), ethyl xanthogenate (EtOCS₂^–, b), 2-mercaptopyridinate (pyS^–, c), and 2-mercaptopyrimidinate (pymS^–, d), to the central platinum atom of the trinuclear Pt­(III)₂,Pt­(II) complex [(C₆F₅)₂Pt^III(μ-PPh₂)₂Pt^III(μ-PPh₂)₂Pt^II(C₆F₅)₂]­(Pt–Pt), 1, gives rise to three different types of complexes: (i) the Pt­(II),Pt­(II),Pt­(II) complex [NⁿBu₄]­[(C₆F₅)₂Pt^II(μ-PPh₂)₂Pt^II{κ²-S,P-μ-(PhS)­PPh₂}­(μ-PPh₂)­Pt^II(C₆F₅)₂], 2a; (ii) the Pt­(II),Pt­(IV),Pt­(II) mixed valence complexes [NⁿBu₄]­[(C₆F₅)₂Pt^II(μ-PPh₂)₂Pt^IV(κ²-S,S′-EtOCS₂)­(μ-PPh₂)₂Pt^II(C₆F₅)₂], 3b, and [NⁿBu₄]­[(C₆F₅)₂Pt^II(μ-PPh₂)₂Pt^IV{κ²N,P-(pymS)­PPh₂}­(μ-PPh₂)₂Pt^II(C₆F₅)₂], 3d; and (iii) the Pt­(II),Pt­(II),Pt­(II) derivatives [NⁿBu₄]­[(C₆F₅)₂Pt^II(μ-PPh₂)₂Pt^II{κ²N,P-μ-(pyS)­PPh₂}­(μ-PPh₂)­Pt^II(C₆F₅)₂], 4c, and [NⁿBu₄]­[(C₆F₅)₂Pt^II(μ-PPh₂)₂Pt^II{κ²N,P-μ-(pymS)­PPh₂}­(μ-PPh₂)­Pt^II(C₆F₅)₂], 4d. Complexes 2a, 4c, and 4d display new Ph₂P­(SL) ligands stemming from the reductive coupling of a PPh₂ group and the S-based anions. Complex 2a exhibits a κ²-S,P bridging coordination mode while 4c and 4d exhibit a κ²-N,P mode in the solid state. In acetone solution, an equilibrium between the κ²-N,P and the κ²-S,P forms was ascertained for complexes with 2-mercaptopyrimidinate and 2-mercaptopyridinate by NMR techniques. Complex 4d evolved, in acetone solution at 323 K, to the Pt­(II),Pt­(II),Pt­(II) complex [NⁿBu₄]­[(C₆F₅)₂Pt^II(μ-PPh₂)­{κ²-P,N-μ-(Pym)­PPh₂}­Pt^II(κ²-S,P-μ-SPPh₂)­(μ-PPh₂)­Pt^II(C₆F₅)₂], 5d. The X-ray diffraction structures of the trinuclear complexes 3′b (the complex having the same anion as 3b but Ph₃PNPPh₃⁺ as the countercation instead of NⁿBu₄) and 4d are described.