Tripotassium hexahydrogen hexamolybdocobaltate(III) heptahydrate, K3[H6CoMo6O24]·7H2O

The very stable title crystals, K3[H6CoMo6O24]·7H2O, that include the well known B-type Anderson–Evans heteropolyoxometalate, were obtained by recrystallization of powder K3[H6CoMo6O24]·nH2O at pH 3.5. The unit cell consists of two different crystallographically discrete [H6CoMo6O24]3− polyanions. The two anions have the Co atoms at inversion centers and have close to \overline 3m symmetry, with Co—O bond lengths in the range 1.898 (3)–1.912 (3) Å, Mo—O bond lengths in the ranges 1.700 (4)–1.726 (4), 1.895 (3)–1.960 (3) and 2.259 (3)–2.313 (3) Å.