Structure of bis-(tetra-ethyl-ammonium) molybdate dihydrate obtained by the reaction between ammonium molybdate and tetra-ethyl-ammonium hydroxide.

Treatment of ammonium molybdate with tetra-ethyl-ammonium hydroxide produces tetra-ethyl-ammonium molybdate that can be recrystallized from aceto-nitrile/ether. The crystal structure reveals the dihydrate compound (C8H20N)2[MoO4]·2H2O. The presence of water mol-ecules in the structure is further supported by FTIR, which demonstrates the corresponding broad signal centered around 3225 cm-1. The supra-molecular structure of (Et4N)2[MoO4]·2H2O demonstrates two-dimensional layers of tetra-hedral molybdate mol-ecules bridged by water mol-ecules, with each Mo-oxo serving as a hydrogen-bond acceptor. The molybdate/water layers are spaced by the layers of disordered tetra-ethyl-ammonium counter-ions. The structural parameters of (Et4N)2[MoO4]·2H2O are presented at 100 and 200 K.