Tetraammonium hexahydrogen hexamolybdonickelate(II) tetrahydrate, (NH4)(4)[H6(N)iMo(6)O(24)]center dot 4H(2)O

Crystals of the title compound, (NH4)(4)[H6NiMo6O24]. 4H(2)O containing the well known B-type Anderson-Evans heteropolyoxometalate, were obtained by recrystallization of powder (NH4)(4)[H6NiMo6O24]. nH(2)O. The anion has the Ni atom at an inversion center and has close to (3) over barm symmetry, with Ni-O bond lengths in the range 2.046 (5)-2.052 (6), Mo-O bond lengths in the ranges 1.701 (6)-1.720 (6), 1.932 (6)-1.954 (7) and 2.216 (6)-2.258 (5) Angstrom.