STRUCTURE AND IR SPECTROSCOPIC PROPERTIES OF THE ANHYDROUS 4-N,N-DIMETHYLAMINOPYRIDINIUM PENTACHLOROPHENOLATE

The structure of the anhydrous 4-N,N-dimethylaminopyridinium pentachrorophenolate has been determined by X-ray diffraction. The crystals are triclinic, space group P (1) over bar with a = 8.637(1), b = 8.865(1), c = 10.235(1) Angstrom, alpha = 83.80(1), beta = 86.88(1), gamma = 89.37(1)degrees and Z = 2. The structure was solved by direct methods and refined to R = 0.031 for 1874 non-zero reflections. The N+-H ... O- hydrogen bond length is 2.579(4) Angstrom and bond angle 165(3)degrees. The pyridinium ring plane is almost perpendicular to the phenolate ring plane (83.9(5)degrees). The ionic character and strongly asymmetric proton position in the hydrogen bond has been confirmed by the IR spectrum.