CRYSTAL-STRUCTURE AND VIBRATIONAL-SPECTRA OF THE 1 1-COMPLEXES AND 1/2-COMPLEXES OF PYRIDINE BETAINE WITH PENTACHLOROPHENOL/

Crystalline complexes of pyridine betaine (PBET) with pentachloropheno l (PCP) have been synthesized and characterized by X-ray diffraction a nd FTIR spectroscopy: PBET .(PCP)(2) (space group P (1) over bar with a=8.748(4), b=11.855(6), c=13.221(6) Angstrom, alpha=66.70(5), beta=74 .06(4), gamma=77.97(4)degrees), PBET . PCP . H2O (space group P2(1)/c with a=8.616(2), b=27.610(6), c=7.0760(10), a=90, beta=104.82(3), gamm a=90 degrees), PBET . PCP . HOMe and PBET . PCP. In PBET .(PCP)(2) the betaine carboxylate group is linked to two phenol molecules by hydrog en bonds of 2.582(6) and 2.611(6) Angstrom. In PBET . PCP . H2O a cent rosymmetric molecular complex is formed by two formula units, where tw o carboxylate groups are bridged by two water molecules to form an eig ht membered ring with four O-H ... O hydrogen bonds of 2.703(4) and 2. 715(5) Angstrom, respectively; each water molecule, in rum, forms a hy drogen bond of 2.580(4) Angstrom to PCP. The IR spectrum of PBET . PCP . HOMe is consonant with a structure in which the betaine carboxylate group accepts both PCP and HOMe. (C) 1997 Elsevier Science B.V.