X-ray and spectroscopic characterisation of cobalt(III) and nickel(II) complexes with 2-(2-pyridyl)iminotetrahydro-1,3-thiazine hydrochloride•water (1/2) (PyTzHCl•2H2O) in the solid state and study of its interaction with cobalt(II) and nickel(II) in aqueous solution

We have carried out the study of the interaction of cobalt(II) and nickel(II) chloride salts with 2-(2-pyridyl)iminotetrahydro-1,3-thiazine hydrochloride (.) water (1/2) (PyTzHCl (.) 2H(2)O) in order to determine what complex species can be formed, with the aim of evaluating the different behaviour of the complexes with respect to the free ligand. The compounds carbonato-kappa(2)O,O'-bis[2-(2-pyridyl-kappaN)amino-5.6-dihydro-4H-1,3-thiazine-kappaN]cobalt(III) chloride (.) water (1/6.6), [Co(CO3)(PyTz)(2)]Cl (.) 6.6H(2)O, and diaquabis[2-(2-pyridyl-kappaN)amino-5,6-dihydro-4H-1,3-thiazine-kappaN]nickel(II) chloride (.) water (1/6), [Ni(PyTz)(2)(H2O)(2)]Cl-2 (.) 6H(2)O, have been isolated and their crystal and molecular structure determined by X-ray diffraction. Both complex cations show a distorted octahedral geometry. The solid phases were also characterized through elemental analysis, magnetic susceptibility, UV-Vis-NIR (UV-Visible-Near IR) diffuse reflectance and infrared spectroscopy. Likewise, the equilibria study of PyTzHCl (.) 2H(2)O with Co(II) and Ni(II) at 298 K and 0.1 M ionic strength in aqueous solution was performed by means of potentiometric titration. (C) 2004 Elsevier Ltd. All rights reserved.