AN INFRARED STUDY ON MATRIX-ISOLATED BENZOIC-ACID

The infrared spectra of benzoic acid and deuterobenzoic acid embedded in Ar matrices were obtained. The only benzoic acid conformer with syn . position of O-H and C=O groups was found to fix in the matrices. We have demonstrated that both a raise of benzoic acid concentration and a matrix annealing lead to formation of H-bonded benzoic acid dimers. The results of semiempirical AMI calculations allowed us to determine probable structures of the dimers observed. The interpretation of the experimental IR spectra was carried out by normal-coordinate analysis for benzoic acid monomer and dimer.