High-Valent Manganese in Polyoxotungstates. 3. Dimanganese Complexes of γ-Keggin Anions

Abstract
Dimanganese-substituted γ-Keggin heteropoly tungstates have been synthesized by reaction of the lacunary species γ-[(SiO4)W10O32]8- with appropriate mixtures of MnII and MnO4-. The crystal structure of [(CH3)3(C6H5)N]4[(SiO4)W10MnIII2O36H6]·2CH3CN·H2O (anion 1) was determined by X-ray diffraction. Crystallographic data: space group P1̄, a = 12.951(3) Å, b = 14.429(3) Å, c = 20.347(4) Å, α = 81.95(3)°, β = 88.92(3)°, γ = 67.48(3)°, V = 3475.2(13) Å3, and Z = 2. The final R value is 7.29% for 15861 reflections with I > 2σ(I). The anion has the anticipated γ-Keggin structure with virtual C2v symmetry. The two Mn cations occupy adjacent, edge-shared octahedra with bridging hydroxo and terminal aqua ligands. Anion 1 can be oxidized and reduced to the corresponding MnIIIMnIV (2) and MnII2 (3) species respectively. The magnetic susceptibility of 1 between 2 and 300 K indicates that the MnIII cations are antiferromagnetically coupled, with J = −17.0 cm-1 and g = 1.965. No simple magnetic behavior was observed for 2 or 3.

This publication has 15 references indexed in Scilit: