Hydrogen bonds and conformational analysis of bis(1-methylisonicotinate) hydrochloride monohydrate by X-ray diffraction, vibrational spectra and B3LYP calculations

摘要

In the crystal structure of bis(1-methylisonicotinate) hydrochloride monohydrate, (MIN)(2)H.Cl-H2O, 1-methylisonicotinate betaines are hemiprotonated and form a homoconjugated cation through a short asymmetric O . H . O hydrogen bond of length 2.456(3) angstrom. Water molecules and Cl- anions are linked alternatively by hydrogen bonds of lengths 3.202(3) and 3.282(2) angstrom into planar zigzag chains along the [c] direction. The Cl- anion additionally interacts electrostatically with two positively charged nitrogen atoms of the neighboring MIN molecules. The most stable conformers of (MIN)(2)H . Cl . H2O, (MIN)(2)H . Cl, (MIN)(2)H . H2O and (MIN)(2)H have been analyzed by the B3LYP/6-31G(d,p) calculations in order to determine the influence of the anion and water molecule on the hydrogen bond in the homoconjugated MIN . H . MIN unit. The FTIR spectrum of (MIN)(2)H . Cl . H2O shows a broad and intense absorption in the 1500-400 cm(-1) region, typical for short hydrogen bonds. The bands at 3416 and 3378 cm(-1) confirm the presence of medium-strong hydrogen bonds between water molecules and Cl- anions. (c) 2006 Elsevier B.V. All rights reserved.