Crystal and molecular structure, hydrogen bond and electrostatic interactions of bis(1-methylisonicotinate)hydrogen perchlorate studied by X-ray diffraction, DFT calculations, FT-IR, Raman and NMR spectroscopes

The crystal structure of bis(1-methylisonicotinate)hydrogen perchlorate, (MIN)(2)H center dot ClO4, has been studied by X-ray diffraction, DFT calculations, FT-IR, Raman, H-1 and C-13 NMR spectra. The crystals are monoclinic, space group P2(1)/n, with a pair of MIN molecules bridged by a short asymmetrical O center dot H center dot O hydrogen bond of 2.461(5) angstrom. The COO groups are twisted by 80.55 degrees with respect to the plane of the pyridine ring. The ClO4 anion interacts electrostatically with the positively charged nitrogen atoms of the neighbouring MIN molecules. The most stable conformer of isolated (MIN)(2)H center dot ClO4 and two homoconjugated cations, (MIN)(2)H, have been analyzed by the B3LYP/6-31G(d,p) calculations in order to determine the influence of the anion on the hydrogen bonds in MIN center dot H center dot MIN unit. The FT-IR spectrum of the (MIN)(2)H center dot ClO4 shows a broad and intense absorption in the 1500-400cm(-1) region, typical of short hydrogen bonds. The isotopic ratio, nu OHO/nu ODO, is close to unity, indicating that the hydrogen bond is acentric (pseudo-type A). (c) 2007 Elsevier B.V. All rights reserved.