Stability and structures of gaseous In2MoO4, In2WO4 and In2W2O7

Abstract

A number of gaseous oxyacid salts have been identified by Knudsen effusion mass spectrometry by vaporizing In₂O₃ from molybdenum or tungsten double two-temperature cells. The stability of gaseous molecules In₂MoO₄, In₂WO₄, and In₂W₂O₇ was deduced from the measurements. The structures and molecular parameters of all investigated salts were obtained using quantum chemical calculations. On the basis of equilibrium constants measured for gas-phase reactions, the standard enthalpies of formation were determined to be −855 ± 33, −773 ± 30, and −1565 ± 30 kJ mol⁻¹ for In₂MoO₄, In₂WO₄, and In₂W₂O₇ respectively. Overall the results obtained allowed us to estimate the standard formation enthalpy of In₂MoO₃, In₂WO₃, and In₂Mo₂O₇ to be −519, −467 and −1530 kJ mol⁻¹, respectively, with an accuracy of ±40 kJ mol⁻¹.