Three N2O2 ligands derived from the condensation of 1,2-cyclohexanediaminewith salicylaldehyde, acetylacetone and benzoylacetone.

The standard ( p ⁰=0.1 MPa) molar enthalpies of formation, at T=298.15 K, in the gaseous phase, for three tetradentate Schiff bases involving a N₂O₂ set, N, N’-bis(salicylaldehydo)cyclohexanediimine (H₂salch), N, N’-bis(acetylacetone)cyclohexanediimine (H₂acacch) and N, N’-bis(benzoylacetone)cyclohexanediimine (H₂bzacch), were determined from their enthalpies of combustion and sublimation, obtained by static bomb calorimetry in oxygen and by the Knudsen effusion technique, respectively. The results are compared with identical parameters for related compounds previously studied, resulting from the condensation of salicylaldehyde or β-diketone with aliphatic diamines. [ABSTRACT FROM AUTHOR]