Synthesis and Structure of Strontium and Barium Uranyl Methacrylates
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CTURE OF ORGANIC COMPOUNDS
Synthesis and Structure of Strontium and Barium Uranyl Methacrylates L. B. Serezhkinaa,*, M. S. Grigorievb, V. V. Klepova, N. A. Shimina, and V. N. Serezhkina a Samara
b Frumkin
National Research University, Samara, 443011 Russia Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, 119071 Russia *e-mail: [email protected] Received November 10, 2017; revised January 9, 2018; accepted January 12, 2018
Abstract—Synthesis, X-ray diffraction analysis, and IR spectroscopy of Sr2[UO2(CH2C(CH3)COO)3]4 · 26H2O (I) and Ba2[UO2(CH2C(CH3)COO)3]4 · 26H2O (II) (CH2C(CH3)COO− is a methacrylate ion) crystals have been performed. The uranium-containing structural units I and II are one-core complexes [UO2(CH2C(CH3)COO)3]−, which belong to the crystallochemical group AB301 (А = UO22 + , B01 = CH2C(CH3)COO−) of uranyl complexes. Is established that the parallel orientation of methacrylate anions of neighboring uranium-containing complexes plays an important structure-forming role in crystals I and II. The bulk layers formed due to the interactions of methacrylate anions contain voids, which are occupied by Sr or Ba cations. Linking of structural fragments into a framework is due to the formation of a system of hydrogen bonds and electrostatic and van der Waals interactions. DOI: 10.1134/S1063774519020251
INTRODUCTION Coordination polymers of transition metals, where unsaturated carboxylates play the role of linkers, are of particular interest for researchers due to their unusual physical and physicochemical properties: ability to ion exchange [1], proton conductivity [2], photocatalytic activity [3], etc. However, directed synthesis of these coordination polymers is hindered by a limited number of synthesized and studied compounds. In particular, the first data on uranyl methacrylates were published quite recently: in 2015 [4]. They concerned the synthesis and crystal structure of UO2(C3H5СОО)2 · nL compounds, in which water (n = 2), N,N-dimethyl carbamide (n = 1.5), or tetramethyl carbamide (n = 1) molecules play the role of electrically neutral ligands L. The list of studied uranyl methacrylates was supplemented with coordination polymers of the [R(H2O)6][UO2(CH2C(CH3)COO)3]2 · 8H2O (R = Mg or Zn) composition [5]. The development of experimental studies in this field is hindered for the following reason: under solar light and in the presence of uranyl ions, methacrylic acid undergoes a photochemical reaction of fast and irreversible polymerization, which manifests itself in aqueous solution turbidity and subsequent formation of a gel-like product [6]. Therefore, studies of uranyl methacrylates remain sparse. In this paper, we report data on the synthesis and crystal structure of two new uranyl complexes with
methacrylate anions: R2[UO2(C3H5СОО)3]4 · 26H2O, where R = Sr (I) or Ba (II). EXPERIMENTAL Synthesis The starting materials were uranium oxide (VI), methacrylic acid, and strontium or barium oxide. Strontium oxide (0.073 g, 0.70 mmol) was dissolved in 10 mL of
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