Publications

Abstract At 298.15 K, the following standard molar enthalpies of formation of the crystalline solids were determined by solution-reaction calorimetry, and the enthalpies of sublimation were measured by microcalorimetry. {A table is presented} (PD, pentan-2,4-dionato; piprm, 2,2-dimethylheptan-3,5-dionato; dibm, 2,6-dimethylheptan-3,5-dionato; ibpm, 2,2,6-trimethylheptan-3,5-dionato; dpm, 2,2,6,6-tetramethylheptan-3,5-dionato.) The mean molar bon-dissociation enthalpy <D>(CuO) was related to D(OH) in the enol form of the diketone, and {<D>(CuO)-0.5D(OH), Hl, enol} was found to equal -(41.8 ± 2.0) kJ · mol-1, constant to within experimental error for all these complexes. Accepting {D(OH), Hl, enol} = (400 ± 20) kJ · mol-1, then <D>(CuO) = (158 ± 10) kJ · mol-1 showing a negligible effect of methyl substitution in the ligand l upon <D>(CuO). © 1984.

Abstract The standard (p^o = 101.325 kPa) molar enthalpies of combustion in oxygen at 298.15 K were measured by static-bomb calorimetry and the standard molar enthalpies of sublimation at 298.15 K were measured by microcalorimetry for 1,2-dihydroxybenzene (catechol) and six alkylsubstituted catechols: {A table is presented}. The increment in the molar enthalpy of formation of the gaseous compound for substitution of alkyl-groups into catechol was found to be approximately the same as the corresponding increment for substitution into benzene. © 1984.

Abstract Standard enthalpies of formation of crystalline samples at 298.15 K were determined by solution calorimetry (oxidative hydrolysis), for ΔH<inf>f</inf>^⊖[Mo<inf>2</inf>(OPrⁱ) <inf>6</inf>, c] = -(1661.8±9) kJ mol^-1 and ΔH<inf>f</inf>^⊖[Mo<inf>2</inf>(OPrⁱ) <inf>8</inf>, c] = -(2292.5±10) kJ mol^-1. The dissociation process [Mo<inf>2</inf>(OPrⁱ)<inf>8</inf>, g] → 2 Mo(OPrⁱ)<inf>4</inf>, g is calculated to be endothermic, ΔH ≈ 184 kJ mol^-1. A bond-enthalpy/bond-length curve is tentatively proposed for Mo-Mo bonds. A similar curve for Mo-O bonds is given, to fit the limited thermochemical data available. It is concluded that the Mo=Mo bond in Mo<inf>2</inf>(OPrⁱ)<inf>8</inf> contributes ca. 200-230 kJ mol^-1 to the binding in this molecule.