Molybdenum(VI) equilibria at high perchloric acid concentration
Equilibria involving the protonation and dimerization of MoO2(OH) (H2O)3+ at high perchloric acid concentration have been investigated. A value for the protonation constant has been determined, log K = -2.23 ± 0.09. Values for the enthalpy and entropy changes for the reaction are ΔH = -21.4 ± 1.8 kJ mol-1 and ΔS = -90 ± 6 J mol-1 K-1 in 6.29 M HClO4. For the dimerization reaction the values pertaining to 3.0 M Na(H)ClO4 are ΔH = -30 ± 5 kJ mol-1 and ΔS = -63 ± 10 J mol-1 K-1 as determined by enthalpimetric titrations. Thermodynamic quantities for the conversion of [MoO4]2- the various mono- and dinuclear cationic species are reported. (C) 2000 Elsevier Science Ltd.