Crystal Structure of trans-Diaquabis(3-aminobenzoato-O)-bis(nicotinamide-N)cobalt(II)

Abstract

ciency of this vitamin leads to a loss of copper from the body, known as pellagra disease. The nicotinic acid derivative, N,N-diethylnicotinamide (DENA), is an important respiratory stimulant. The title compound was prepared by dissolving CoSO4·7(H2O) (2.81 g, 0.01 mol) and NA (2.44 g, 0.02 mol) in water (75 ml) and sodium-3-aminobenzoate (3.18 g, 0.02 mol) in water (25 ml) and then adding the solutions. The mixture was set aside for crystallization at ambient temperature for a few days. A structure determination of the title compound was undertaken in order to determine the ligand properties of NA and benzoate ligands, and to compare the coordination geometries when the NA ligands are substituted for water in complexes [Co(p-O2NC6H4COO)2(H2O)4] (I) and [Co(p-H2NC6H4COO)2(H2O)4] ( ). The title compound is a monomeric complex with cobalt in a center of symmetry. All ligands are monodentate and the O atoms of each water molecule and benzoate group form a slightly distorted square-planar coordination around the Co atom, which is completed to a Jahn-Teller distorted octahedron by the pyridine N atoms of NA at 2.153(3)A (Fig. 2). There are intraand inter-molecular hydrogen bonds between the nicotinamide N3 and O4 atoms [N O 2.236(6)A], and the non-coordinated O3i atom and the water O2 atom [O O 2.583(6)A, symmetry code: (i) –x, –y, –z], respectively. Similar hydrogen bonds are observed in (I) [2.59 A], ( ) [2.592(3) A], [Co(C7H5O2)2(C6H6N2O)2(H2O)2] ( ) [2.580(2)A] and [Co(C7H4NO4)2(C6H6N2O)2(H2O)2] ( ) [2.634(5)A]. The configuration around the Co atom is given by the torsion angles (Table 4). The Co atom is out of the C1, O1, O3 plane by 0.645(2)A. The dihedral angle between the carboxyl group and the phenyl ring is 24.1(4) . The corresponding ones are 13.0(2) and 23.7(3) in complexes ( ) and ( ), respectively. Most 1043 ANALYTICAL SCIENCES OCTOBER 1999, VOL. 15