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CTURE OF ORGANIC COMPOUNDS

Synthesis and XRay Structural Investigation of K2(H5O2)[UO2(C2O4)2(HSeO3)] D. V. Pushkina, E. V. Peresypkinab, L. B. Serezhkinaa, A. V. Marukhnova, and A. V. Virovetsb a

b

Samara State University, ul. Akademika Pavlova 1, Samara, 443011 Russia Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, ul. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia email: [email protected] Received September 21, 2010

Abstract—The synthesis and Xray diffraction analysis of K2(H5O2)[UO2(C2O4)2(HSeO3)] single crystals have been performed. This compound crystallizes in the triclinic system with the unitcell parameters a = 6.7665(4) Å, b = 8.8850(4) Å, c = 12.3147(7) Å, α = 94.73°, β = 90.16°, γ = 92.11°, sp. gr. P 1 , Z = 2, and R = 0.019. The basic structural units are island [UO2(C2O4)2(HSeO3)]3− groups, which belong to the − 01 2+ 2− AB2 M1 crystallochemical group of uranyl complexes (A = UO2 , B01 = C2O4 , and M1 = HSeO3 ). Uranium

containing complexes are linked through K+ and H5O2+ ions and via a system of hydrogen bonds with the par ticipation of oxonium hydrogen atoms in this structure. DOI: 10.1134/S1063774511030254

INTRODUCTION Currently, oxalatecontaining compounds of ura nium(VI) are of great interest, because oxalates are used for metal extraction and purification. A number of studies have been published where heteroligand complexes (in which the uranium atom and the oxalate ion simultaneously coordinate an acid ligand of another nature) were synthesized and their struc tural features were revealed. To date, the structures of the compounds where the uranyl and oxalate ions simultaneously coordinate acid ligands such as NCS, SO24− , SeO24− , or OH– ions have been investigated. When studying the products of interaction in an aque ous solution of selenious acid, uranium(VI) oxide, and potassium oxalate, a K2(H5O2)UO2(C2O4)2(HSeO3) (I) single crystal was selected. Since there are no data on the structure of uranyl compounds containing simultaneously oxalate and hydroselenite (or selenite) ions, we performed an Xray diffraction analysis of this complex.

continuous stirring. Note that the interaction between the agents is accompanied by the partial precipitation of elementary selenium. Isothermal evaporation of the solution obtained after removal of the undissolved phase yielded pale yellow wellfaceted crystals I. The structure of compound I was established by an Xray diffraction analysis of single crystals. The crys tallographic data and results of the structure refine ment are listed in Table 1. The structure was inter preted by the direct method and refined by the full matrix leastsquares method in the anisotropic approximation for nonhydrogen atoms. Hydrogen atoms were localized from the difference electron den sity map and refined without geometric restrictions using fixed thermal parameters. The main bond lengths and angles of compound I are given in Table 2. The atomic coordinates and thermal parameters have been deposited with t