The zinc(II) complexes dichloro[2-(3,4-dichlorophenyl)imino-KN-(2-thiazolin-KN-2-yl)thiazolidine]zine(11) (1) and dichloro[2-(3,4-dichlorophenyl)imino-KN-(4H-5,6-dihydro-1,3-thiazin-KN-2-yl)tetrahydrothiazine]zine(II) (2) have been isolated and characterized in the solid state by X-ray diffraction, elemental analysis and IR spectra. In both complexes, the environment around the zinc(II) ion may be described as a distorted tetrahedral geometry, with the metallic atom coordinated to two chlorine atoms [Zn-Cl(l) 2.218(1) angstrom: Zn-Cl(2) = 2.221(1) angstrom], one imino nitrogen [Zn-N(3) = 2.042(2) angstrom] and one thiazoline nitrogen [Zn-N(1) = 2.022(2) angstrom] in complex 1 and to two chlorine atoms [Zn-Cl(1) = 2.216(1) angstrom; Zn-Cl(2) = 2.192(1) angstrom], one imino nitrogen [Zn-N(3) = 2.045(2) angstrom] and one thiazine nitrogen [Zn-N(1) = 2.039(2) angstrom] in complex 2. In addition, we also report in this study the crystal structure of the 2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine (TdTn) ligand as well as the synthesis and characterization by X-ray diffraction, H-1 and C-13 NMR spectra, elemental analysis, IR and electronic spectra of the 2-(3,4-dichlorophenyl)imino-N-(4H-5,6-dihydro-1,3-thiazin-2-yl)tetrahydrothiazine (TzTz) ligand. Besides, we study the phagocytic function in humans neutrophils treated with each complex and ligand aforementioned. (c) 2006 Elsevier Inc. All rights reserved.