Vanadogermanate Cluster Anions

Three novel vanadogermanate cluster anions have been synthesized by hydrothermal reactions. The cluster anions
are derived from the {V18O42} Keggin cluster shell by substitution of VO2+ “caps” by Ge2O(OH)24+ species. In
Cs8[Ge4V16O42(OH)4]·4.7H2O, 1, (monoclinic, space group C2/c (No. 15), Z = 8, a = 44.513(2) Å, b = 12.7632(7)
Å, c = 22.923(1) Å, β = 101.376(1)°) and (pipH2)4(pipH)4[Ge8V14O50·(H2O)] (pip = C4N2H10), 2 (tetragonal, space
group P42/nnm (No. 134), Z = 2, a = 14.9950(7) Å, c = 18.408(1) Å), two and four VO2+ caps are replaced,
respectively, and each cluster anion encapsulates a water molecule. In K5H8Ge8V12SO52·10H2O, 3, (tetragonal,
space group I4/m (No. 87), Z = 2, a = 15.573(1) Å, c = 10.963(1) Å), four VO2+ caps are replaced by Ge2O(OH)24+ species, and an additional two are omitted. The cluster ion in 3 contains a sulfate anion disordered over
two positions. The cluster anions are analogous to the vanadoarsenate anions [V18-nAs2nO42(X)]m- (X = SO3,
SO4, Cl; n = 3, 4) previously reported.