Syntheses and Characterization of Copper(II) and Cobalt(II) Complexes with Tris[2-(benzylamino)ethyl]amine

Two mononuclear complexes [Cu(NCS)(trenb)]ClO4 (1) and [Co(NCS)(trenb)]Cl·H2O (2), where trenb is tris[2-(benzylamino)ethyl]amine, were prepared and characterized by elemental analysis, IR, electronic and EPR spectra. Their crystal structures were determined by X-ray diffraction. Complexes 1 and 2 are both five-coordinated with their metal centers in the distorted trigonal-bipyramidal environment. Each metal(II) ion coordinates with the tetradentate trenb, and one isothiocyanate anion. The two complexes are not isostructural as there are also a chloride and a water molecule in the asymmetric unit of 2. Besides balancing the charge, the chlorides are also involved in intramolecular and intermolecular hydrogen bonds with the secondary amine groups, resulting in a one-dimensional chain structure. UV-VIS spectrum and EPR measurement for 1 have unambiguously confirmed that the five-coordinated structure is retained in solution, even in the donating solvent such as DMF.