New zinc(II), palladium(II) and platinum(II) complexes of dl-piperidine-2-carboxylic acid; X-ray crystal structure of trans-[Zn _2(μ-Ca)_2(Hpa)_2Cl_6] and anticancer activity of some complexes

摘要

New complexes of dl-piperidine-2-carboxylic acid (dl-H_2pa), [Zn(Hpa)(AcO)(H_2O)_2], trans-[Zn_2(μ-Ca) _2(Hpa)_2Cl_6], [M(bpy)(Hpa)]Cl and [M(pa)(PPh_3)_2] (M(II) = Pd, Pt) have been prepared and characterized on the basis of elemental analyses, molar conductivity and thermal measurements, IR, Raman, UV-Vis, NMR (~1H and ~(31)P) and mass spectroscopy. dl-Piperidine-2-carboxylic acids act as bidentate ligands, through the carboxyl oxygen and cyclic nitrogen atoms. The crystal structure of trans-[Zn_2(μ-Ca)_2(Hpa)_2Cl_6], obtained from the addition of ZnCl_2 to dl-H_2pa in either hard tap water or presence of CaCl_2, has been determined by X-ray diffraction. It crystallizes in a triclinic lattice with space group symmetry P1. The complex has two zinc atoms in tetrahedral geometry, each ligated by a carboxyl oxygen and three chlorine atoms. The other carboxyl oxygen atoms from the two Hpa~- ligands are bridged by two calcium atoms, i.e., there are two Zn(Hpa~-)Cl_3 units bridged by two calcium atoms. The free dl-H_2pa and its complexes, trans-[Zn_2(μ-Ca) _2(Hpa)_2Cl_6], [Pd(bpy)(Hpa)]Cl and [M(pa)(PPh_3)_2] (M(II) = Pd, Pt) have been tested against the serous ovarian cancer ascites, OV 90 cell line.