THE STRUCTURE AND IR-SPECTRUM OF THE HYDROGEN-BONDED ADDUCT OF 2,6-DICHLORO-4-NITROPHENOL WITH 3,4-DIMETHYLPYRIDINE

The adduct of 2,6-dichloro-4-nitrophenol with 3,4-dimethylpyridine crystallizes in the space group P1BAR with a = 7.124(4), b = 13.469(3), c = 15.797(3) angstrom, alpha = 103.80(2), beta = 97.94(3), gamma = 102.16(3)-degrees, Z = 4. Two crystallographically non-equivalent molecules of the adduct occur in the lattice. The OHN intermolecular hydrogen bridges are very short, with values of 2.532(3) and 2.529(3) angstrom. The geometry of the molecules and the localization of the bridge proton indicate that the proton is transferred to the N atom although the IR spectrum is close to those of ''critical'' hydrogen bridges where the proton is shared between the 0 and N atoms.