STRUCTURE OF DIAQUA-BIS(ETHYLENEDIAMINE)COPPER(II) SALTS WITH ANIONS OF CARBAMIC ACIDS
L.A.Kovbasyuk, I.O.Fritsky, V.N.Kokozay, T.S.Iskenderov
Department of Chemistry, Shevchenko University, Kiev 252033, Ukraine
Removal of CO2 from gaseous streams is an important procedure in different industrial technologies. One of the ways used in industry to eliminate CO2 from gas mixtures is its absorption on liquid amines or their solutions, which affords formation of carbamates. The presence of metal ions may play catalytic function in the reactions of CO2 uptake.
We report herein two novel complexes of diaqua-bis(ethylenediamine)copper(II) with anions of N-carboxy-glycine [Cu(en)2(H2O)2](OOCCH2NH-COO)H2O (1) and ethylendiamine-biscarbonic acid [Cu(en)2(H2O)2](OOCNHCH2CH2NH-COO)2H2O (2) obtained as a result of CO2 uptake by the amine-containing ligands in the presence of Cu2+ ions. 1 was obtained by direct synthesis by interaction of cupric powder with glycine hydrochloride in methanol solution upon heating in the air. 2 was isolated as a result of reaction between copper(II) anionic complex with pyruvoylamide with ethylenediamine and formaldehyde in methanol. In both cases formation of carbamates is connected with uptake of atmospheric CO2 by the reaction mixtures. The crystal structures of 1 (Fig.1) and 2 (Fig.2) are formed by [Cu(en)2(H2O)2]2+ cations, carbamic acids anions and solvate water molecules. The complex cations of 1 and 2 consist of two ethylenediamine molecules co-ordinated in equatorial plane (Cu-N = 2.005(3) - 2.021(3) Ä for 1 and 1.996(2) and 2.022(2) Ä for 2), and water molecules occupying the apical positions of distorted octahedra (Cu-O = 2.590(4) and 2.740(4)Ä for 1 and 1.556(3)Ä for 2). The extended H-bond systems in 1 and 2 unit the elements of the structures.
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