Polyoxo Alkoxides of Vanadium: The Structures of the Decanuclear Vanadium(IV) Clusters [V₁₀O₁₆{CH₃CH₂C(CH₂O)₃}₄]^4- and [V₁₀O₁₃{CH₃CH₂C(CH₂O)₃}₅]⁻

The hydrothermal reaction of a mixture of vanadium oxides with CH₃CH₂C(CH₂OH)₃ in the presence of NH₄Cl yields (NH₄)₄[V₁₀O₁₆{CH₃CH₂C(CH₂O)₃}₄]•4H₂O (I). In contrast, the reaction of vanadium oxides with the same ligand, using Et₄NCl as mineralizer, yields (Et₄N)[V₁₀O₁₃{CH₃CH₂C(CH₂O)₃}₅] (II). Both I and II exhibit structures based on the decavanadium core, {V₁₀O₂₈}. While 12 doubly and triply bridging oxo groups of the [V₁₀O₂₈]^6- prototype are replaced by alkoxy oxygens of the ligands in I, 15 doubly and triply bridging oxo groups are replaced in II. In addition to the incorporation of alkoxy ligands into the {V₁₀O₂₈} core, I and II are unusual in that the vanadium sites exhibit the V(IV) oxidation state rather than V(V) as observed for the parent core. The relatively small structural distortions associated with this reduction of the core are noteworthy. Crystal data for (NH₄)₄[V₁₀O₁₆{CH₃CH₂C(CH₂O)₃}₄]•4H₂O (I): space group, C2/c; a = 17.320 (2) Å; b = 24.904 (3) Å; c= 12.430 (2) Å; β = 106.32 (1)°; V= 5146 (3) ų; Z = 2; D(calc) = 1.840 g/cm³; structure solution and refinement based on 4053 reflections, R = 0.042. Crystal data for (Et₄N)[V₁₀O₁₃{CH₃CH₂C(CH₂O)₃}₅] (II): space group, P2₁/c a = 12.290 (2) Å; b = 19.115 (2) Å; c = 23.701 (4) Å; β = 98.80 (1)°; V = 5502 (2) ų; Z = 4; D(calc) = 1.815 g/cm³; 4436 reflections, R = 0.079. An analogous compound to II, (Me₄N)_2/3(Et₄N)_1/3[V₁₀O₁₃{CH₃C(CH₂O)₃}₅]•0.69H₂O (III) was prepared in a similar fashion. Crystal data for (Me₄N)_2/3(Et₄N)_1/3[V₁₀O₁₃{CH₃C(CH₂O)₃}₅]•0.69H₂O (III): space group, P2₁/n; a = 12.235 (2) Å; b = 22.484 (6) Å; c = 53.439 (13) Å; β = 92.61 (2)°; V= 14685 (6) ų; Z = 12; D(calc) = 1.913 g/cm³; 11994 reflections, R = 0.0851.