Transition Metal(II) Complexes of Vitamin B13 with Monodentate Orotate(1-) Ligands

Abstract

The formation of bisorotate(1-) complexes of the type [M(C<inf>5</inf>H<inf>3</inf>N<inf>2</inf>O<inf>4</inf>)<inf>2</inf>(H<inf>2</inf>O)<inf>4</inf>]·nH<inf>2</inf>O (M=Co, Ni, Zn and n=2, 4) was achieved by the reaction of ammonium orotate with the corresponding M(II) ions. The crystal structure of [Co(C<inf>5</inf>H<inf>3</inf>N<inf>2</inf>O<inf>4</inf>)<inf>2</inf>(H<inf>2</inf>O)<inf>4</inf>]·2H<inf>2</inf>O was determined by single crystal X-ray diffraction analysis. Each Co(II) ion in the monomeric Co(C<inf>5</inf>H<inf>3</inf>N<inf>2</inf>O<inf>4</inf>)<inf>2</inf>(H<inf>2</inf>O)<inf>4</inf> units adapts a slightly distorted octahedral geometry comprised of two monodentate orotate anions and four H<inf>2</inf>O ligands. Columnar packing of pyrimidine rings along the c axis leads to the formation of layers that propagate parallel to the b axis and the adjacent layers are linked by hydrogen bonds forming a 3D lattice. Complexes of nickel and zinc were assumed to contain monodentate bound orotate ligands as well on the basis of physical and spectroscopic data. © 2006 Elsevier B.V. All rights reserved.