Low-dimensional compounds containing bioactive ligands. IV. Unusual ionic forms of 5-chloroquinolin-8-ol

Abstract

Bis(5-chloro-8-hydroxyquinolinium) tetrachloridopalladate(II), (C9H7ClNO)2[PdCl4], (I),catena-poly[dimethylammonium [[dichloridopalladate(II)]-μ-chlorido]], {(C2H8N)[PdCl3]}n, (II), ethylenediammonium bis(5-chloroquinolin-8-olate), C2H10N22+·2C9H5ClNO−, (III), and 5-chloro-8-hydroxyquinolinium chloride, C9H7ClNO+·Cl−, (IV), were synthesized with the aim of preparing biologically active complexes of PdIIand NiIIwith 5-chloroquinolin-8-ol (ClQ). Compounds (I) and (II) contain PdIIatoms which are coordinated in a square-planar manner by four chloride ligands. In the structure of (I), there is an isolated [PdCl4]2−anion, while in the structure of (II) the anion consists of PdIIatoms, lying on centres of inversion, bonded to a combination of two terminal and two bridging Cl−ligands, lying on twofold rotation axes, forming an infinite [–μ2-Cl–PdCl2–]nchain. The negative charges of these anions are balanced by two crystallographically independent protonated HClQ+cations in (I) and by dimethylammonium cations in (II), with the N atoms lying on twofold rotation axes. The structure of (III) consists of ClQ−anions, with the hydroxy groups deprotonated, and centrosymmetric ethylenediammonium cations. On the other hand, the structure of (IV) consists of a protonated HClQ+cation with the positive charge balanced by a chloride anion. All four structures are stabilized by systems of hydrogen bonds which occur between the anions and cations. π–π interactions were observed between the HClQ+cations in the structures of (I) and (IV).