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)2PtIII(μ-PPh2)2PtIII(μ-PPh2)2PtII(C6F5)2](Pt–Pt), 1, gives rise to three different types of complexes: (i) the Pt(II),Pt(II),Pt(II) complex [NnBu4][(C6F5)2PtII(μ-PPh2)2PtII{κ2-S,P-μ-(PhS)PPh2}(μ-PPh2)PtII(C6F5)2], 2a; (ii) the Pt(II),Pt(IV),Pt(II) mixed valence complexes [NnBu4][(C6F5)2PtII(μ-PPh2)2PtIV(κ2-S,S′-EtOCS2)(μ-PPh2)2PtII(C6F5)2], 3b, and [NnBu4][(C6F5)2PtII(μ-PPh2)2PtIV{κ2N,P-(pymS)PPh2}(μ-PPh2)2PtII(C6F5)2], 3d; and (iii) the Pt(II),Pt(II),Pt(II) derivatives [NnBu4][(C6F5)2PtII(μ-PPh2)2PtII{κ2N,P-μ-(pyS)PPh2}(μ-PPh2)PtII(C6F5)2], 4c, and [NnBu4][(C6F5)2PtII(μ-PPh2)2PtII{κ2N,P-μ-(pymS)PPh2}(μ-PPh2)PtII(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)2PtII(μ-PPh2){κ2-P,N-μ-(Pym)PPh2}PtII(κ2-S,P-μ-SPPh2)(μ-PPh2)PtII(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.