Synthesis and structural characterization of 10 Group Metal complexes with anionic tridentate-S,N,N donor Schiff bases derived from pyridylbenzothiazolines.

The ring opening transformation of three substituted 2-(2-pyridyl)benzothiazolines of general formula [(C6H4NCS)(C5H4 N)R] (R = C5H4N, 1; R = C6H5, 2; R = H, 3) was studied by their reaction with metal chlorides of Ni(II), Pd(II), and Pt(II). In these reactions, the anionic tridentate Schiff bases {Ln}? coordinated to metal ions were identified. Seven metallic complexes of type [M(Ln)Cl] [M = Pd, n = 1, R = C5H4N, (1a); n = 2, R = C6H5, (2a); n = 3, R = H, (3a). M = Pt, n = 1, R = C5H4N, (1b); n = 2, R = C6H5, (2b); n = 3, R = H, (3b), and M = Ni, R = C6H5, (2c)] were characterized in solution by NMR and vibrational spectroscopy in solid state. Crystal structures of benzothiazolines 1 and 2 and complexes 1a?3a, 1bDMSO, and 2c were analyzed by X-ray diffraction studies. In all cases, mononuclear complexes with a distorted square planar geometry were obtained. For compounds 1?3, the predominance of the benzothiazoline (ring form) over the Schiff base (open form) as well as the formation of the [Pd(Ln)Cl] (n = 1?3) complexes were studied by DFT calculations at the PBEPBE/(Def2-TZVP,SDD) level in gas phase.