Preparation and Properties of Group 13 (Ga, In, Tl) Heterometallic Single and Corner-Shared Double Cube Derivatives of [Mo₃S₄(H₂O)₉]⁴⁺ and Related Studies

Abstract

New routes are described for the preparation of cuboidal complexes [Mo(3)InS(4)(H(2)O)(12)](5+), [Mo(3)GaS(4)(H(2)O)(12)](5+), and [Mo(6)InS(8)(H(2)O)(18)](8+) from the incomplete cuboidal [Mo(3)S(4)(H(2)O)(9)](4+). A comparison of the aqueous solution properties of the single cubes, [Mo(3)GaS(4)(H(2)O)(12)](5+) and [Mo(3)InS(4)(H(2)O)(12)](5+), and the double cubes, [Mo(6)InS(8)(H(2)O)(18)](8+) and [Mo(6)TlS(8)(H(2)O)(18)](8+), the total listing of group 13 derivatives, is reported. The single cube [Mo(3)InS(4)(H(2)O)(12)](5+) can be quantitatively converted into the double cube by reductive (H(3)PO(2) or BH(4)(-)) addition of [Mo(3)S(4)(H(2)O)(9)](4+). The double cubes are O(2) sensitive, much more so in HCl than Hpts (pts(-) = p-toluenesulfonate), and are oxidized by H(+) in HCl solutions with the formation of H(2) (detected by gas chromatography). The single cubes are less reactive in air, and are only oxidized by H(+) at higher ( approximately 4 M) levels. Stoichiometry measurements with [Co(dipic)(2)](-) and [Fe(H(2)O)(6)](3+) as 1e(-) oxidants were used to confirm charges on the clusters. In the absence of reduction potentials, rate constants for outer-sphere [Co(dipic)(2)](-) oxidations give a measure of redox properties. Oxidation of [Mo(6)InS(8)(H(2)O)(18)](8+) with [Co(dipic)(2)](-) provides a route back to the single cube [Mo(3)InS(4)(H(2)O)(12)](5+). Properties of [W(3)InS(4)(H(2)O)(12)](5+) and [Mo(6)InO(2)S(6)(H(2)O)(18)](8+) obtained from [W(3)S(4)(H(2)O)(9)](4+) and [Mo(3)OS(3)-(H(2)O)(9)](4+) are also considered. The single cube [W(3)InS(4)(H(2)O)(12)](5+) is >10(3) times more reactive with [Co(dipic)(2)](-) than [Mo(3)InS(4)(H(2)O)(12)](5+), consistent with reducing properties W > Mo. No evidence was obtained in these studies for [Mo(3)TlS(4) (H(2)O)(12)](5+), [Mo(6)GaS(8)(H(2)O)(18)](8+), or the recently proposed 6+ analogue of [Mo(3)GaS(4)(H(2)O)(12)](5+).