High-Valent Manganese in Polyoxotungstates. 3. Dimanganese Complexes of gamma-Keggin Anions.
Dimanganese-substituted gamma-Keggin heteropoly tungstates have been synthesized by reaction of the lacunary species gamma-[(SiO(4))W(10)O(32)](8)(-) with appropriate mixtures of Mn(II) and MnO(4)(-). The crystal structure of [(CH(3))(3)(C(6)H(5))N](4)[(SiO(4))W(10)Mn(III)(2)O(36)H(6)].2CH(3)CN.H(2)O (anion 1) was determined by X-ray diffraction. Crystallographic data: space group P&onemacr;, a = 12.951(3) Å, b = 14.429(3) Å, c = 20.347(4) Å, alpha = 81.95(3) degrees, beta = 88.92(3) degrees, gamma = 67.48(3) degrees, V = 3475.2(13) Å(3), and Z = 2. The final R value is 7.29% for 15861 reflections with I > 2sigma(I). The anion has the anticipated gamma-Keggin structure with virtual C(2)(v)() 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 Mn(III)Mn(IV) (2) and Mn(II)(2) (3) species respectively. The magnetic susceptibility of 1 between 2 and 300 K indicates that the Mn(III) cations are antiferromagnetically coupled, with J = -17.0 cm(-)(1) and g = 1.965. No simple magnetic behavior was observed for 2 or 3.
Zhang
Xiao-Yan
XY
Department of Chemistry, Georgetown University, Washington, D.C. 20057, and Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148.
O'Connor
Charles J.
CJ
Jameson
Geoffrey B.
GB
Pope
Michael T.
MT