THE CRYSTAL-STRUCTURES AT 80 K AND IR-SPECTRA OF THE COMPLEX OF 4-METHYLPYRIDINE WITH PENTACHLOROPHENOL AND ITS DEUTERATED ANALOG

The crystal structures of the complex of 4-methylpyridine with pentach lorophenol (MP-PCP) and its deuterated analogue (MP-PCP-d) were determ ined at 80 K by X-ray diffraction. The MP-PCP complex crystallizes in the space group P (1) over bar with a = 7.267(7), b = 8.966(9), c = 13 .110(14) Angstrom, alpha = 99.70(8), beta = 118.16(9), gamma = 103.38( 8)degrees and Z = 2 and the MP-PCP-d complex in the monoclinic Cc spac e group with a = 3.826(2), b = 27.54(2), c = 13.209(12) Angstrom, beta = 101.38(9)degrees and Z = 4. The O ... H ... N bridge bond distance of 2.515(4) Angstrom is significantly shorter than that determined at room temperature (2.552(4) Angstrom) and the O-D .. N bond length of 2 .628(6) Angstrom is only slightly shorter than at room temperature (2. 638(3) Angstrom). The temperature dependence of the IR spectra confirm s the symmetrization of the OHN hydrogen bond.