Molecular structure of N-(4-carboxybutyl)pyridinium perchlorate studied byX-ray diffraction, FTIR spectroscopy, PM3 and SAM1 calculations

The crystal structure of N-(4-carboxybutyl)pyridinium perchlorate was deter mined by X-ray diffraction as triclinic, space group P (1) over bar with a = 7.351(1), b = 8.673(2), c = 10.673(2) Angstrom, alpha = 99.84(3)degrees, beta = 102.07(3)degrees, gamma = 105.11(3)degrees and Z = 2. The molecules are present as a centrosymmetric hydrogen-bonded dimer and the ClO4- anions interact electrostatically with the positively charged nitrogen atoms and additionally with some H-C groups. The FTIR spectrum of the compound shows a broad absorption with many sub-maxima between 3000 and 2500 cm(-1), typic al for the dimeric form of carboxylic acids. The PM3 and SAM1 calculations confirmed the dimeric structure for two isolated ionic pairs. (C) 1999 Else vier Science B.V. All rights reserved.