Synthesis and Structure of PbUO2(CH2C(CH3)COO)4

Abstract

A new compound with the formula PbUO₂(mac)₄, where mac is the methacrylate ion CH₂C(CH₃)COO⁻, has been synthesized and studied by X-ray diffraction and IR spectroscopy. The equatorial plane of a UO₇ pentagonal bipyramid contains the oxygen atoms of four anions, three of which are coordinated to the uranyl ions monodentately, and one is coordinated bidentately, forming mononuclear complexes [UO₂(mac)₄]²⁻. Each lead ion is bound to eight oxygen atoms of five methacrylate ions of three such complexes. As a result, lead ions bond uranium-containing complexes into electroneutral chains [PbUO₂(mac)₄], which are the main structural units of crystals. The different roles of the four crystallographically nonequivalent methacrylate ions in the crystal structure determine the crystal-chemical formulas of the chains as A′AB⁰¹B¹¹(B²¹)₂, where A′ = Pb²+; A=UO₂²⁺; B⁰¹, B¹¹, and B²¹ = mac. The chains are linked by the system of hydrogen bonds to form a framework. The effect of the nature of R²⁺ cations on the structure of methacrylate uranylates is considered.