Synthesis and characterization of perhalophenyltin derivatives. Study of their reactivity toward phosphine gold(I) chlorides

The (perhalophenyl)tin derivatives [SnR4] (1–3) and [SnR3Cl] (4–6) (R = C6F5, C6F3Cl2, C6Cl5) were prepared from SnCl4 and LiR or [SnR4] in the appropriate molar ratio, while the dinuclear complexes [SnR3]2 (7–9) were obtained by treatment of [SnR3Cl] with potassium under toluene reflux. Complexes 2, 6·0.5toluene and 7 were structurally characterized, the latter displaying a Sn–Sn bond of 2.808(7) Å, which indicates a strong tin–tin bond with covalent character in solid state. The hexaaryldistannanes 7–9 undergo transmetallation reactions with gold(I) derivatives, such as [AuCl(PPh3)] or [(AuCl)2(μ-dppm)], affording the neutral species [AuR(PPh3)] (10–12) or [(AuR)2(μ-dppm)] (13–15) or the ionic product [Au3Cl2(μ-dppm)2][Sn(C6F5)3Cl2] (16). The crystal structures of 14·CH2Cl2, 15 and 16·2CH2Cl2 were determined by X-ray diffraction, the latter showing a Au3 nearly equilateral triangular core in the cation with gold–gold contacts of 3.128(7) and 3.227(12) Å. The main difference between the molecular structures of 14·CH2Cl2 and 15 (both of them displaying intramolecular gold–gold contacts of 3.142(6) and 3.160(4) Å, respectively) is the presence of an intermolecular Au⋯Au interaction of 3.2126(8) Å in the case of the C6F3Cl2 complex that gives rise to a tetranuclear unit.