SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF 5-COORDINATE AND 6-COORDINATE COBALT(II) COMPLEXES OF TRIPODAL LIGAND, TRIS-(2-BENZIMIDAZOLYLMETHYL)AMINE

The various cobalt(II) complexes were synthesized and characterized us ing tris-(2-benzimidazolylmethyl)amine (ntb) as a ligand where the ntb plays as a tripodal tetradentate ligand to form complexes with a trig onal pyramidal geometry. The complexes have 5 and 6 coordinate cobalt( II) ions depending on the additional ligand used. In each complex the additional ligand, chloride anion, or acetate anion occupies the ''ope n'' site trans to the apical tertiary nitrogen atom of ntb ligand. Com plex 1, [Co(II)(ntb)Cl]Cl has a trigonal bipyramidal geometry. This ge ometry was easily constructed using ntb as a tetradentate ligand and c hloride as a monodentate ligand. The complex is isostructural to the c orresponding manganese(II) complex. Crystal data are as follows: [Co(I I)(ntb)Cl]Cl.MeOH, 1. triclinic space group <P(1)over bar>; a = 13.524 (2) Angstrom, b = 14.037(2) Angstrom, c = 17.275(1) Angstrom; alpha = 78.798(9), beta = 84.159(8)degrees, gamma = 65.504(9)degrees; V = 2929 .6(6) Angstrom(3); Z = 4; R1 = 0.0715, wR2 = 0.1461 for reflections of I > 2 sigma(I). Six coordinate complex 2 [Co(ntb)(OAc)](OAc) was synt hesized using ntb as a tetradentate ligand and acetate as a bidentate chelating ligand.