FEATURES OF THE STRUCTURE OF COPPER-CONTAINING COMPOSITES BASED ON Cu+ MALEATE COMPLEXES

Abstract

Quantum chemical modeling (Gaussian 09, AIM2000, Chemcraft 1.8) of the interaction of copper atoms with acidic maleate complexes Cu⁺ [Cu(НМ)(Н₂О)] made it possible to identify two types of thermodynamically stable binuclear π-complexes of the general composition [Cu₂(НМ)(H₂O)₂]. Type A is characterized by a framework structure in which both Cu⁺ ions and Cu⁰ atoms form π-bonds with sp²-hybridized carbon atoms of the vinyl fragment of the maleate ion within separate six-membered cycles (-Cu-С-С=О-Н-О-). Type B is a linear σ-connection of a hydrated copper atom with the carboxyl oxygen of the maleate ion. The closeness of the formation energies of molecules A and B (−114.39 kJ/mol and −127.84 kJ/mol, respectively) indicates a high probability of their simultaneous formation during the synthesis of the composite {Cu(НМ)⁺Cu}. X-ray diffraction analysis of composite samples confirmed that there is no metallic copper phase in it, but there is a phase of a new substance – products of the interaction of Cu⁰ atoms with π-complexes [Cu(НМ)(Н₂О)]. The analysis of the obtained results of our theoretical and experimental research indicates that during the synthesis of copper-containing composites {Cu(НМ)⁺Cu} by partial chemical reduction of maleate complexes of Cu⁺, a mixture of mononuclear π-complexes [Cu(HM)(H₂O)] with various binuclear π-complexes [Сu₂(НМ)(Н₂О)₂] is formed.