Synthesis, Structural and Spectroscopic Characterization of Cr-III, Fe-III, Co-III, Ni-II and Cu-II Complexes with an Asymmetric 1,3,4-Thiadiazole Ligand

摘要

The reaction of the new asymmetric 1,3,4-thiadiazole-based ligand 2-[(5-ethylthio-1,3,4-thiadiazol-2-yl)hydrazonomethyl] phenol (H1ETHP) with various third-row transition metal salts resulted in the formation of six new mononuclear complexes [Cr(ETHP)(2)]ClO4(1), [Fe(ETHP)(2)][FeCl4] (2), [Co(ETHP)(ETHP-(H))] (3), [Ni(ETHP)(H1ETHP)]Cl (4), [Ni(ETHP)(H1ETHP)](ClO4) (5), [Ni(ETHP)(H1ETHP)]Br (6), and one tetranuclear complex [Cu2Cl3(ETHP)(H1ETHP)](2) (7). H1ETHP and all complexes have been analyzed by single crystal X-ray diffraction. Structural analysis of 1-6 reveals complexes of the [ML2](n+)-type (n = 0,1), in which the mono anionic ligand ETHP coordinates in a tridentate NNO fashion via its imine, thiadiazole and phenolate functional groups. Complex 7 has also been investigated by variable-temperature magnetic susceptibility measurements and shows weak antiferromagnetic exchange interactions between the copper centers. The g values for the copper ions in the tetramer were obtained by EPR spectroscopy. All compounds were found to display an extended hydrogen bond network via their N-H or O-H ligand functional groups towards the corresponding counterions, solvent molecules or neighboring complex cations. The connectivity of the complexes results in the formation of supramolecular chains or, in the case of 4, a 3D-network including large solvent accessible cavities.