The First Dinuclear Orotate Complex: Syntheses, Spectral, Thermal and Structural Characterization of Supramolecular Orotate Complexes of Nickel(II) and Copper(II) with 2-Hydroxyethylpyridine

Abstract

Two novel orotate complexes, mononuclear [Ni(HOr)(H<inf>2</inf>O)<inf>2</inf>(etpy)]·H<inf>2</inf>O (1) and dinuclear [Cu(μ-HOr)(etpy)]<inf>2</inf> (2) (etpy = 2-hydroxyethylpyridine, HOr2- = dianionic orotate), have been prepared and characterized by elemental analyses, spectroscopic (IR, UV-vis), thermal, magnetic and single crystal X-ray diffraction studies. The mononuclear Ni(II) complex crystallizes in the triclinic space group P over(1, ̄) and the dinuclear copper(II) complex crystallizes in the monoclinic space group P2<inf>1</inf>/c. The mononuclear complex consists of individual units in which nickel(II) lies on the inversion center and has octahedral coordination by bidentate HOr2-, bidentate etpy and two aqua ligands. The dinuclear copper(II) complex composed of a double-orotate bridge and bidentate etpy ligands. Each HOr2- ligand simultaneously exhibits chelating bidentate and bridging coordination modes. HOr2- is tricoordinated to one copper atom through N3 atom of pyrimidine ring, one oxygen atom of the carboxylate group as a bidentate ligand and to the other copper ion via the other oxygen of the carboxylate group. The structural units are joined into the framework by the hydrogen bonds in 1 and 2. © 2008 Elsevier B.V. All rights reserved.