Preparation, Structure, and Reactivity of Heterometallic Sn-Containing Single- and Double-Cube Derivatives of [Mo₃Se₄(H₂O)₉]⁴⁺ and [W₃Se₄(H₂O)₉]⁴⁺

The preparation and properties of Sn-containing derivatives of trinuclear MIV3Se44+ incomplete cuboidal clusters [Mo3Se4(H2O)9]4+ and [W3Se4(H2O)9]4+ are described. Addition of SnII to [Mo3Se4(H2O)9]4+ gives the single-cube [Mo3SnSe4(H2O)12]6+ in 2 M Hpts (pts- = p-toluenesulfonate) and [Mo3(SnCl3)Se4(H2O)9]3+ in 2 M HCl. The structure has been determined by X-ray crystallography on (NH2Me2)6 [Mo3(SnCl3)Se4(NCS)9]·0.5H2O. The reaction of Sn metal with [Mo3Se4(H2O)9]4+ gives the first example of an Se-containing corner-shared double cube, characterized by X-ray crystallography as [Mo6SnSe8(H2O)18](pts)8·2Hpts·28H2O. The clusters [Mo3SnSe4 (H2O)12]6+ and [Mo6SnSe8(H2O)18]8+ are also characterized by the ease of elution in Dowex chromatography, ICP elemental analyses, and the stoichiometries of the oxidation with [Co(dipic)2]-. The preparation of the single-cube [W3SnSe4(H2O)12]6+ in 2 M Hpts, [W3(SnCl3)Se4 (H2O)9]3+ in 2 M HCl, is also described. Conversion of [Mo3SnSe4(H2O)12]6+ into corner-shared double-cubes [Mo6SnSe8 (H2O)18]8+, [Mo6SnSe4S4(H2O)18]8+, [Mo3W3SnSe8(H2O)18]8+, and [Mo3W3SnSe4S4(H2O)18]8+ was achieved by reductive addition of [Mo3Se4(H2O)9]4+, [Mo3S4(H2O)9]4+, [W3Se4(H2O)9]4+, and [W3S4(H2O)9]4+ using BH4-. A similar procedure was used for the conversion of [W3Se4(H2O)9]4+ into [W6SnSe8(H2O)18]8+. Transfer of SnII is observed in the reaction of [Mo3S4(H2O)9]4+ with [Mo3SnSe4(H2O)12]6+, [W3SnSe4(H2O)12]6+, and [W3SnS4(H2O)12]6+. With the inclusion of similar reactions of [Mo3Se4(H2O)9]4+ etc., the order of affinities for SnII uptake is Mo3S44+ > Mo3Se44+ > W3Se44+ > W3S44+. The displacement of InI from [W3InSe4(H2O)12]5+ by SnII is also consistent with equilibrium processes involving dissociation of the heteroatom.