Hydrogen Bonded Networks and a Self-Assembled 1D Water Cluster in Nickel(II) and Copper(II)-Orotate Complexes

Abstract

Three Ni(II) and Cu(II)-orotate complexes with 1,3-propanediamine (pen) and N-methylethylenediamine (nmen), [Ni(HOr)(H<inf>2</inf>O)<inf>2</inf>(pen)] (1), [Cu<inf>2</inf>(μ-HOr)<inf>2</inf>(pen)<inf>2</inf>] (2) and {[Cu(μ-HOr)(nmen)]·3H<inf>2</inf>O}<inf>n</inf> (3) (H<inf>3</inf>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 NH<inf>2</inf> 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 R22(12) and R22(8) ring motives, respectively. Complex 2 consists of dimeric [Cu<inf>2</inf>(μ-HOr)<inf>2</inf>(pen) <inf>2</inf>] 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···O hydrogen bonds, constitute centrosymmetric R22(8) rings through the plane (1 0 1). The hydrogen bonds between pen and HOr ligands result in R22(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 π···π interactions. The lattice water molecules, forming a 1D water cluster, function as a glue to form a 3D supramolecular network through extended hydrogen bonding. © 2010 Elsevier Ltd. All rights reserved.