AN UNUSUAL GEOMETRICAL AND SPECTROSCOPIC ISOTOPIC EFFECT IN THE SOLID COMPLEX OF 4-METHYLPYRIDINE WITH PENTACHLOROPHENOL

Article abstract of DOI:10.1016/0022-2860(90)80495-6

The structure of the complex of 4-methylpyridine with deuterated pentachlorophenol (MP PCP-d) has been determined by X-ray diffraction.The crystals are monoclinic, space group Cc, with a = 3.942(3), b = 27.73(3), c = 13.297(9) Angstroem, β = 101.81(6) deg and Z = 4.The structure, solved by direct methods, has been refined to R = 0.036 for 3600 non-zero (hkl) and (<*>) reflections.The crystals of MP PCP-d are non-isomorphous with the complex MP PCP.The OD group is engaged in a bifurcated interaction to give O-D...N and O-D...Cl(6) hydrogen bonds with lengths 2.638(3) and 3.002(3) Angstroem and angles 141(4) and 115(4) deg, respectively.The anomalous spectroscopic isotopic ratio ν(OHN)/ν(ODN) is lower than 1 and has been explained by drastic changes in the hydrogen bridge geometry.