Synthesis, physico-chemical characterizations of new copper and cobalt alkoxide

Abstract

This work aimed to the synthesis, structure determination and characterization of new copper or cobalt complexes involving α or β diol. Multi-nuclear complexes of 3d transition metals with M4O4 cubane corehave remarkable magnetic in the field of single molecule magnet, and also very attractive biological and catalytic properties. These metal complexes are obtained by adopting the so called “chimie douce” method.The heating temperature does not exceed the boiling temperature of the used polyol (generally does not exceed 200°C for ethylene glycol and 1,3-propanedol). The goal of the experimental work is to avoid the formation of mixed alkoxo acetate metal complexes by varying several chemical and physical parameters such as: heating temperature, metal initial concentration, polyol/metal molar ratio, reaction time,hydrolysis ratio...etc. In this context, two chemical systems M(CH3COO)2.xH2O-ethylene glycol, (M= Cu, Co and x= 1 and 4for Cu and Co respectively), and Cu(CH3COO)2.xH2O-1,3-propanediol have been considered. The two alkoxides of copper are the only alkoxides obtained in our laboratories. These alkoxides have been characterized using powder X-ray diffraction, infrared spectroscopy, solid ultra violet spectroscopy and have been photocatalytically examined. Also, thermal gravimetric analysis, and magnetic studies have been established for Cu(1,3-PD). The alkoxides of cobalt have been synthesized and characterized elsewhere.The structure of Cu3(CH3COO)2(CH3CH2O2)2 obtained from the reaction between copper acetate and ethylene glycol can be described as distorted square pyramidal CuO5, CH3COO- and (OCH3CH2O)2-entities. The structure determination of pure copper alkoxide from ethylene glycol is in progress. The structure determination of both obtained metal alkoxides from 1,3-PD revealed a distorted cubane M4O4(M=Co, Cu) in the complex core. Although, strong structure correlation exists between the structure of cobalt alkoxide and copper alkoxide, the two compounds are not isostructural, indeed the unit cell parameters and the space group are different. Moreover, Co-O distances are different from Cu-O distances, while in CoO5, the five Co-O distances are almost equal. In CuO5 square pyramidal, the four Cu-Odistances are close, and one Cu-O distance is longer. Numerous perspectives of this work can be achieved. Firstly, to further test and study the catalyticproperties of the obtained compounds. Secondly, to improve their physical and chemical properties bychanging either the ligand or the central 3d transition metal