Experimental IR, Raman and ab initio molecular orbital study of the 4-methylbenzenesulfonate anion

The 4-methylbenzenesulfonate (p-toluenesulfonate) anion was studied by ab i nitio quantum chemical methods, and the IR and Raman spectra of oxonium p-t oluenesulfonate were recorded. The geometry of the anion was fully optimize d at the HF SCF/3-21+G(d) level of theory. The theoretically predicted stru cture was in very good agreement with the crystallographic results. Harmoni c vibrational analysis was performed for the optimized structure (at the sa me level of theory). The predicted harmonic vibrational frequencies based o n the ab initio force field were shown to be very valuable for an accurate assignment of the internal vibrational modes of the anion in 4-methylbenzen esulfonate salts. (C) 1999 Elsevier Science B.V. All rights reserved.