Structure of complexes of nitrilo tris methylene phosphonic acid with copper, [CuN(CH 2 PO 3 ) 3 (H 2 O) 3 ] and Na 4 [C

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Structure of Complexes of Nitrilo Tris Methylene Phosphonic Acid with Copper, [CuN(CH2PO3)3(H2O)3] and Na4[CuN(CH2PO3)3]2 ⋅ 19H2O, As Bactericides and Inhibitors of Scaling and Corrosion N. V. Somova and F. F. Chausovb a University

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of Nizhni Novgorod, pr. Gagarina 23, Nizhni Novgorod, 603950 Russia Udmurt State University, ul. Universitetskaya 1, Izhevsk, 426034 Russia e-mail: [email protected], [email protected] Received February 5, 2014

Abstract—Nitrilotris methylene phosphonate triaqua copper and octasodium bis(nitrilotris methylene phosphonate cuprate(II)) nonadecahydrate have been synthesized and investigated. [CuN(CH2PO3)3(H2O)3] is crystallized in the sp. gr. P21/c, Z = 4, a = 9.2506(2) Å, b = 15.9815(2) Å, c = 9.5474(2) Å, β = 113.697(2)°. The copper atom is coordinated by oxygen atoms in the configuration of elongated octahedron; the ligand (of bridge type) links neighboring copper atoms. Na8[CuN(CH2PO3)3]2 ⋅ 19H2O is crystallized in the sp. gr. P21/c, Z = 2, a = 11.24550(10) Å, b = 17.38980(10) Å, c = 13.5852(2) Å, β = 127.8120(10)°. This complex is chelating; the copper atom closes three five-membered N–C–P–O–Cu cycles with a shared Cu–N bond. Copper is coordinated in a distorted trigonal–bipyramidal configuration. DOI: 10.1134/S1063774515010228

INTRODUCTION Copper salts and complexes of organophosphonic acids are applied as efficient bactericides [1] and inhibitors of scaling and steel corrosion in water-supply circulation systems, cooling systems for technological equipment, and heating systems [2–4]. In contrast to many commercial bactericides, copper has a relatively low toxicity for warm-blooded animals and people [5]. However, the wide commercial application of copper-phosphonate bactericides and inhibitors is hindered by the low reproducibility of technological and ecological quality factors of products from set to set. The reason is as follows: the structures of the corresponding compounds have been poorly investigated because of the complexity and variety of coordinations of transition metal atoms by amino-polyphosphonic acids [6], which is why bridge or chelating complexes, as well as ionic compounds with outer-sphere coordination, can be formed under different conditions. The interaction of reagents often leads to the formation of a mixture of products with different structures. A study of the mechanism of steel corrosion inhibition by phosphonate Zn complexes showed that their action is determined by the reactions of inner-sphere substitution and surface complexing [7–9]. Apparently, this holds true for Cu complexes, the structure of which directly affects the thermodynamics and kinetics of the aforementioned processes. The need for

copper–phosphonate bactericides and inhibitors with high and stable technological and ecological characteristics makes the synthesis of new compounds of this class and analysis of their structure urgent. There are spectral studies of complexes of cobalt, nickel, copper, and zinc with nitrilo tris methylene phosphonic acid N(CH2PO3H2

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