Two hybrid transition-alkali metal complexes, K-2[M(DPA)(2)]center dot 7H(2)O(s) (M = Cu and Ni, H(2)DPA = pyridine-2,6-dicarboxylic acid), were structurally determined by X-ray crystallography. In accordance with Hess's law, two reasonable thermochemical cycles were designed and 100 cm(3) of 5% (v/v) dilute aquaammonia was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and products of the supposed reactions in the selected solvent were measured at 298.15K by means of isoperibol solution-reaction calorimeter, respectively. The standard molar enthalpies of formation of K-2[M(DPA)(2)]center dot 7H(2)O(s) (M = Cu and Ni) were derived to be -(3947.7 +/- 4.7) kj mol(-1) and -(4007.8 +/- 4.7) kj mol(-1), respectively. (C) 2011 Elsevier B.V. All rights reserved.