Structural studies of Ni(II), Zn(II) and Cd(II) complexes with saccharinate and 2,2′-bipyridine ligands

The syntheses and properties of the Ni(II) complex [Ni(sac)(bipy)(2)(H2O)]. sac (3) (sacH = saccharin, bipy = 2,2 ' -bipyridine) and crystal structural studies of 3 and two other related derivatives [Zn(sac)(bipy)(2)(H2O)]. sac (5) and [Cd(sac)(2)(bipy)(2)] 6 are described. The Ni and Zn complexes belong to an isostructural series along with the corresponding Mn (1) and Co (2) compounds. These compounds have six coordinate octahedral structures with two mutually cia bipy, one sac(-) ion and the aqua ligands in the coordination sphere, and one uncoordinated sac- ion hydrogen bonded to the aqua ligand, and provide examples of 'cation-anion pair' formation. The Cd complex is also six coordinate octahedral, but in this case the two chelating bipy ligands are mutually trans, and both the sac(-) anions are directly bonded with the metal. The variations of the coordination geometry parameters in the complexes are compared and discussed. (C) 2001 Elsevier Science B.V. All rights reserved.