THERMODYNAMICS OF TRIMETHYLINDIUM ADDUCTS OF N,N',N -TRIALKYL-1,3,5-TRIAZACYCLOHEXANES

Adducts of formula InMe3·C3H6N3R3, where R = Me, Pri or But, have been prepared. The adduct bonding of three lone pairs is shown to be only slightly stronger than a standard one lone-pair adduct bond, and estimated to be between 85 and 90 kJ mol–1. The vapour pressures of these adducts have been determined and interpreted by statistical mechanical techniques to show the presence of disorder within the molecules, both in the alkyl groups and in the adduct bonding. The former is shown to affect the solid phases; its use in modelling the disorder in a crystal structure and in predicting the entropy of phase change to disordered phases is outlined. The latter appears in the liquid and vapour phases and is used to explain melting points and entropies of vaporisation.