Synthesis, structure, and decomposition of (NH4)2[Mo6Cl14] • H2O

Abstract

(NH4)2[Mo6Cl14] · H2O (1) was prepared from reactions of MoCl2 in ethanol with aqueous NH4Cl solution. It crystallizes in the monoclinic space group I2/a (no. 15), Z = 4 with a = 912.3(1), b = 1491.2(2), c = 1724.8(2) pm, β = 92.25(1)̊; R1 = 0.023 (based on F values) and wR2 = 0.059 (based on F2 values), for all measured X-ray reflections. The structure of the cluster anion can be given as [(Mo6Cli6)Cla6] 2- (i = inner, a = outer ligands). Thermal stability studies show that 1 loses crystal water followed by the loss of NH4Cl above 350 °C to yield MoCl2. The water-free compound (NH4)2[Mo6Cl14] (2) was synthesized by solid state reaction of MoCl2 and NH4Cl in a sealed quartz ampoule at 270 °C. No single-crystals could be obtained. Decompositions of 1 and 2 under nitrogen and argon exhibited the loss of NH4Cl at about 350 °C. Decomposition under NH3 resulted in the formation of MoN and Mo2N at 540 °C and 720 °C, respectively.