Influence of steric strain of S,N-heterocycles derivative ligands on the coordination geometry in cadmium(II) nitrato complexes

The new ligands 2-(3,5-dimethyl-1-pyrazolyl)-2-thiazoline (DMPyTn) and 2-(3,5-diphenyl-1-pyrazolyl)-2-thiazoline (DPhPyTn) have been synthesized and characterized, and six cadmium(II) nitrato complexes with these two ligands and four other pyrazole/S,N-heterocyclic derivative ligands with different steric features, previously reported, have been prepared and structurally characterized by means of elemental analysis, single crystal X-ray diffraction and IR spectra, with the objective of determining the role played by the steric strains of the ligands on the metal ion coordination index and geometry. The effect of two factors has been analyzed: the bulk of the pyrazole ring substituents and the size of the S,N-heterocycle. The data indicate that there is a clear influence of the size of the organic ligands on the coordination environment of the Cd(II) ion. (C) 2011 Elsevier Ltd. All rights reserved.