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

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journal contribution
posted on 24.04.2019, 00:00 by Consuelo Fortuño, Antonio Martín, Piero Mastrorilli, Stefano Todisco, Mario Latronico
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)2PtII2-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)2PtIV2-S,S′-EtOCS2)­(μ-PPh2)2PtII(C6F5)2], 3b, and [NnBu4]­[(C6F5)2PtII(μ-PPh2)2PtIV2N,P-(pymS)­PPh2}­(μ-PPh2)2PtII(C6F5)2], 3d; and (iii) the Pt­(II),Pt­(II),Pt­(II) derivatives [NnBu4]­[(C6F5)2PtII(μ-PPh2)2PtII2N,P-μ-(pyS)­PPh2}­(μ-PPh2)­PtII(C6F5)2], 4c, and [NnBu4]­[(C6F5)2PtII(μ-PPh2)2PtII2N,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}­PtII2-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.

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