Abstract
Resulting from a collaboration among three departments, the standard enthalpies of formation of some crystalline bis(8-hydroxyquinolate) metal complexes were determined by reaction-solution calorimetry. Enthalpies of hydrolysis were measured for several samples of each complex using various acidic solvents. 8-hydroxyquinoline is written as Hox. At 298.15 K, Δ f H θ m(M(ox) 2,cr)/(kJ mol −1) values are: Mg(ox) 2, −516.0 ± 4.0; Ca(ox) 2, −607.7 ± 4.4; Sr(ox) 2, −585.9 ± 4.1; Ba(ox) 2, −573.4 ± 4.5; Cu(ox) 2, −103.3 ± 3.3; Zn(ox) 2, −271.5 ± 3.6; Cd(ox) 2, −179.6 ± 4.3; Pb(ox) 2, −145.3 ± 3.8; Mn(ox) 2, −307.1 ± 3.7; Fe(ox) 2, −219.7 ± 4.5; Co(ox) 2, −160.4 ± 4.2; Ni(ox) 2, −165.5 ± 5.6. Where feasible, standard enthalpies of sublimation at 298.15 K were determined by measuring vapour pressures as functions of temperature. Δ g cr H θ m(M(ox) 2)/(kJ mol −1) values are: Mg(ox) 2, 230.2 ± 4.0; Cu(ox) 2, 168.7 ± 7.3; Zn(ox) 2, 183.2 ± 6.3; Cd(ox) 2, 201.7 ± 7.5; Pb(ox) 2, 187.1 ± 6.2; Mn(ox) 2, 194.6 ± 10.4; Co(ox) 2, 205.3 ± 4.0; Ni(ox) 2, 175.4 ± 6.7. From the standard enthalpies of formation in the gaseous state, the mean metal-ligand dissociation enthalpies were derived and compared with corresponding values for other complexes of these metals.
Published Version
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