Energetics of formation of adducts of N-methyl-2-pyrrolidone with zinc(II) family metal halides - A thermochemical study

Article abstract of DOI:10.1016/S0040-6031(97)00313-4

Thermochemical data for adducts of N-methyl-2-pyrrolidone (NMP) with zinc(II), cadmium(II) and mercury (II) halides have been obtained from solution calorimetry. The technique provided the values for the dissolution enthalpies (Δ_iH⁰) of MX₂ (M = Zn, Cd, Hg; X = Cl, Br, I) metal halides, the NMP lactam and MX₂.nNMP adducts, which were used to determine the standard molar enthalpies of acid-base reaction in the condensed state (Δ_rH⁰) for the adducts, by using appropriate thermodynamic cycles. From Δ_rH⁰ values and literature data, the following thermochemical parameters have been calculated: standard enthalpy of formation (Δ_fH⁰), standard enthalpy of decomposition (Δ_dH⁰), standard lattice enthalpy (Δ_lattH⁰), standard enthalpy of acid-base reaction in the gaseous phase (Δ_gH⁰) and the mean dissociation enthalpy of the metal-oxygen bond, D (M-O) have been established. In order to evaluate the methyl group influence on the donor oxygen strength of the NMP lactam, the obtained thermochemical data are compared with those previously published for analogous 2-pyrrolydone (BuL) compounds. The influence of the ionic and covalent character of the metal halides has been taken into account in the metal-oxygen interaction processes.