Complexes of 2,6-bis(hydroxymethyl)pyridine with different copper(II) salts involving the anions chloride, perchlorate, nitrate and acetate. Synthesis and crystal structures of the complexes

Abstract

Complexes of 2,6-bis(hydroxymethyl)pyridine (dhmp) with different Cu II salts [CuCl 2·6H 2O, Cu(ClO 4) 2·6H 2O, Cu(NO 3) 2·3H 2O, Cu(CH 3COO) 2· H 2O] are prepared (1-5, respectively), studied by IR, and their crystal structures reported. Dependent on the anion kind, influences on the distortion of the coordination polyhedron, the distribution of donor sites, the formation of a mono- or binuclear complex, and the resultant packing structure of the complex are observed, although in no case the counterions of the used Cu II salts or water of hydration were found in the co-ordination sphere. Crystal structures of 1-5 indicate hexaco-ordination of the Cu II ions with N 2O 4-environment and show that 1-4 are mononuclear 2:1 (L:M) complexes, but 5 is a binuclear 4:2 complex. Crystallization of Cu(ClO 4) 2·6H 2O with dhmp yielded two different complexes (2/3). In 3, one of the dhmp components is mono-deprotonated and acts as an anionic ligand. The same behavior is found in 5. Whereas in the neutral ligand complexes 1, 2 and 4 the basal planes are occupied by O donors, and N atoms are in the axial positions of the octahedrons, in 3 and 5 the bases are formed by two O and two N donor atoms, and O atoms are in the axes. Moreover, complex 3 shows the N atoms in trans position, but 5 in cis position. The packing of the cationic complex units is typical of strong and weak H bond interactions involving the counterions and hydroxylic or aromatic hydrogen atoms to yield complex network structures.