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

Complexes of 2,6-bis(hydroxymethyl)pyridine (dhmp) with different Cu-II salts [CuCl(2)(.)6H(2)O, Cu(ClO4)(2)(.)6H(2)O, Cu(NO3)(2)(.)3H(2)O, Cu(CH3COO)(2)-H2O] 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 N2O4-environment and show that 1-4 are mononuclear 2:1 (L:M) complexes, but 5 is a binuclear 4:2 complex. Crystallization of Cu(ClO4)(2)(.)6H(2)O 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 0 donors, and N atoms are in the axial positions of the octahedrons, in 3 and 5 the bases are formed by two 0 and two N donor atoms, and 0 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.