Some nickel(II) complexes with pentadentate and tridentate heterocyclic N- and S-donor ligands

High-spin Ni(II) complexes of the linear pentadentate ligand 2,6-bis([2′-aminophenylthio]methyl)pyridine (Batp) and the tridentate ligands ([2′-aminophenylthio]ethyl)pyridine (Atep) 1,5-bis(N-methylbenzimidazol-2′-yl)-3-oxapentane (Mbeo) have been prepared. Crystal structures of the complexes [Ni(Batp)(H2O)](CF3SO3)2 (2) and [Ni(Atep)2](ClO4)2 (4) reveal pseudooctahedral coordination. Tetragonal distortion in [Ni(Mbeo)2](ClO4)2 (5) is evident from the longer Ni–O and shorter Ni–N bond lengths. From the electronic spectrum of 5, the tetragonal distortion parameter Dt and the in-plane Dqxy and axial Dqz ligand field parameters are calculated. The three Ni(II) complexes exhibit irreversible cathodic electrochemistry.