Synthesis and characterisation of new binuclear complexes containing a relatively strong Pt to Hg donor bond. Molecular structure of complex [Pt(C^P)(μ-O2CCH3)2Hg(O2CCH3)]

Abstract

[{Pt(C^P)(μ-O₂CCH₃)}₂] (1A) (C^P = CH₂-C₆H₄-P(o-tolyl)₂-κC,P) reacts with Hg(O₂CCH₃)₂ and [{Pt(C^P)(μ-O₂CCF₃)}₂] (1B) reacts with Hg(O₂CCF₃)₂ in a 1 ∶ 2 molar ratio to afford the neutral complexes [Pt(C^P)(μ-O₂CCH₃)₂Hg(O₂CCH₃)] (2) and [Pt(C^P)(μ-O₂CCF₃)₂Hg(O₂CCF₃)] (3) respectively. They also react with equimolar amounts of HgX₂ (X = Cl, Br, I) to give mixtures of the corresponding neutral complexes [Pt(C^P)(μ-O₂CR)₂HgX] (R = CH₃, X = Cl 4, Br 5, I 6; R = CF₃, X = Cl 7, Br 8, I 9) and [{Pt(C^P)(μ-X)}₂] (X = Cl, Br, I). Complexes 4–6 could be isolated from the mixtures as pure samples but complexes 7–9 could not. Complexes [Pt(C^P)(μ-O₂CR)₂HgX] (R = CH₃, X = Cl 4, Br 5, I 6; R = CF₃, X = Cl 7, Br 8, I 9) can also be prepared by treatment of the carboxylate derivatives [Pt(C^P)(μ-O₂CR)₂Hg(O₂CR)] (R = CH₃2, CF₃3) with methanol solutions of HX (X = Cl, Br, I) in 1 ∶ 1 molar ratio, this being the only way to obtain pure samples of complexes 7–9. The study of the molecular structure of 2 by X-ray diffraction reveals the existence of a very strong Pt to Hg donor bond (Pt–Hg = 2.6131(6) Å ). The NMR data of 2 are in agreement with its observed structure in the solid state. The similarity of the NMR data of all complexes leads us to propose the same structure for all of them, which seems to be retained in solution at room temperature.