Aqueous and non-aqueous soluble salts of manganese(IV)-containing Kegg
in polyoxotungstates [(XO(4))(W11MnO36H)-O-IVx](n-) (X = Si, B, and Zn
) have been prepared by chemical and electrolytic oxidation of corresp
onding manganese(II) or manganese(III) anions, and have been character
ized by magnetic susceptibilities, ESR and X-ray absorption near-edge
spectroscopy (XANES), in addition to conventional elemental and spectr
oscopic analyses. The crystal structure of dark brown K-7[(ZnO4)(W11Mn
O36H)-O-IV].19H(2)O (I) was determined by X-ray diffraction and reveal
s a disordered Keggin anion. Manganese EXAFS investigation of I and th
e corresponding manganese(II) complex, which contains a terminal Mn-II
-OH2 group, strongly indicates that I contains Mn-IV-OH (r(Mn-O) simil
ar to 1.82 Angstrom) rather than Mn-IV=O.