Syntheses and crystal structures of zinc(II) complexes with three kinds of piperidine carboxylic acids

Zinc(II) complexes with dl-piperidine-2-carboxylic acid (Hpipe-2), dl-piperidine 3-carboxylic acid (Hpipe-3), and piperidine-4-carboxylic acid (Hpipe-4):ZnCl2(Hpipe 2)2, ZnCl2(Hpipe-3)2(H2O)3, and ZnCl2(Hpipe-4) have been prepared and characterized by means of IR spectra and thermal analysis. The crystal structures of [ZnCl2(Hpipe-3)2]·3H2O and [ZnCl2(Hpipe-4)] have been determined by X-ray diffraction. The crystal of [ZnCl2(Hpipe-3)2]·3H2O is monoclinic with the space group P21/c. The zinc atom is in a tetrahedral geometry, ligated by two carboxylato oxygen atoms and two chlorine atoms. The crystal of [ZnCl2(Hpipe-4)] is triclinic with space group P1̄. This complex consists of a binuclear molecule bridged by two carboxylato oxygen atoms. The zinc atom is in a tetrahedral geometry ligated by two carboxylato oxygen atoms and two chlorine atoms.