Triammonium hexahydroxidooctadecaoxidohexamolybdogallate(III) heptahydrate

Abstract

The title compound, (NH4)3[GaMo6(OH)6O18]·7H2O, contains two centrosymmetric GaMo6 B-type Anderson cluster units consisting of central GaO6 octahedra surrounded by a hexagonal assembly of MoO6 edge-sharing octahedra. Like other B-type Anderson clusters, where the central Mo atom is substituted with a di- or trivalent metal ion, the central six μ3-oxido bridges are protonated. The average Ga—O bond length is 1.97 (1) Å, whereas the average Mo—O distances are 2.29 (2), 1.94 (1) and 1.709 (5) Å, respectively, for Mo—(μ3-OH), Mo—(μ2-O) and Mo=O bonds. In the crystal structure, the Ga(μ3-OH)6Mo6O183− polyanionic clusters are surrounded by NH4+ cations and solvent water molecules, forming an extended network of hydrogen bonds.