Abstract
Infrared spectra from complexes of 2-chloro-4-nitrobenzoic acid and some amines with proton affinities (PA) ranging from 205.9 to 229.4 kcal mol
−1 are studied. A characteristic relationship between the center of gravity of the infrared protonic vibrational band and proton affinity is obtained. A theoretical study using the atom superposition and electron delocalization molecular orbital method (ASED-MO) is performed. A good correlation between the theoretical and experimental results is found, both theoretical and experimental results showing that the 3,5-dimethylpyridine complex represents the critical point at which 50% proton transfer is obtained.