Hydrogen bonded networks and a self-assembled 1D water cluster in nickel(II) and copper(II)-orotate complexes

Three Ni(II) and Cu(II)-orotate complexes with 1,3-propanediamine (pen) and N-methylethylenediamine (nmen), [Ni(HOr)(H2O)(2)(pen)] (1), [Cu-2(mu-HOr)(2)(pen)(2)] (2) and {[Cu(mu-HOr)(nmen)]center dot 3H(2)O}(n) (3) (H(3)Or = orotic acid) have been synthesized and characterized by thermal analysis, IR spectroscopy and single crystal X-ray diffraction techniques. In complex 1, the Ni(II) ion has a distorted octahedral geometry. The hydrogen bonds play an important role in the formation of the 3D polymeric structure of complex 1. The carboxylate groups interact with NH2 groups of pen ligands, and HOr ligands are mutually hydrogen bonded to each other through the pyrimidine N and exocyclic O atoms, giving rise to R-2(2)(12) and R-2(2)(8) ring motives, respectively. Complex 2 consists of dimeric [Cu2(mu-HOr)(2)(Pen)(2)] units in which the Cu(II) ions have square pyramidal coordination geometries with bridging oxygen atoms at the pyramid apex. The HOr ligands, linked by N-H center dot center dot center dot O hydrogen bonds, constitute centrosymmetric R-2(2)(8) rings through the plane (1 0 1). The hydrogen bonds between pen and HOr ligands result in R-2(2)(8) rings centered at (n + 1, 0, 1/2) (n = zero or integer). Complex 3 is a 1D coordination polymer, in which the orotate moiety acts as a bridging ligand in the structure. The [Cu(HOr)(nmen)] units are linked by carboxylate oxygen atoms of HOr, which result in a zigzag chain structure along the a axis. Two adjacent 1D coordination polymers are connected through pi center dot center dot center dot pi interactions. The lattice water molecules, forming a ID water cluster, function as a glue to form a 3D supramolecular network through extended hydrogen bonding. (C) 2010 Elsevier Ltd. All rights reserved.