Thermochemistry of aniline-derivative adducts of nickel(II) acetylacetonate

The compounds [Ni(acac)(2)(L)(2)] (where acac is acetylacetonate and L is a niline (an), 2,6-dimethylaniline (dimean), o- or m-chloroaniline (o- or m-c lan)) were synthesized and characterized by melting points, elemental analy sis, TG-DTG, and DSC curves and electronic and IR spectroscopy. The enthalp ies of dissolution of the adducts, Ni(II) acetylacetonate and ligands in a 1 : 3 (v/v) mixture of aqueous HCl 1.2 M and methanol, were measured and by using thermochemical cycles the following thermochemical parameters for th e adducts have been determined: The standard enthalpies for the Lewis acid/ base reaction (Delta(r)H(theta)), the standard enthalpies of formation (Del ta(f)H(theta)), the standard enthalpies of decomposition (Delta(D)H(theta)) , the lattice standard enthalpies (Delta(M)H(theta)) and the standard entha lpies of the Lewis acid/base reactions ire the gaseous phase (Delta(r)H(the ta)(g)). The mean standard enthalpies of the nickel-nitrogen bonds have bee n estimated. (C) 1999 Elsevier Science B.V. All rights reserved.