Americium dioxocations in solid. Crystal structures and absorption spectra of the new complexes [AmVO2(dipy)OOCCH3(H2O)] and Cs2[(AmVIO2)2(SO4)3]

Single crystals of the two new compounds [AmVO2(dipy)OOCCH3(H2O)] (I) and Cs2[(AmVIO2)2(SO4)3] (II) have been synthesized and their structures have been determined by X-ray structural analysis. IR and optical spectra of polycrystalline compounds I and II were measured and interpreted. The structure I is formed by electroneutral complexes [AmVO2(dipy)OOCCH3(H2O)], in which dioxocations AmO2+ are coordinated by two N atoms of a bidentate-chelating dipy ligand, two O atoms of a bidentate-chelating acetate anion and one O atom of water molecule. Due to a different nature of ligands, the distances and bond angles in the equatorial plane of AmO2+ have a significant spread. The structure II is built of interlaced anionic and cationic layers. Anionic layers [(AmVIO2)2(SO4)3]n2n- contain AmO22+ groups and two types of SO42- anions: tridentate- and tetradentate-bridging. Each AmO22+ is coordinated in a monodentate way by three tridentate anions and two tetradentate ones. The coordination numbers of the outer Cs+ cations are equal to 10 for Cs(1), and 16 for Cs(2). The dioxocations AmO2 in both structures are linear and almost symmetric. Analysis of the obtained absorption spectra showed that the number and intensity of the absorption bands in them are dependent both on the equatorial ligand nature, and on the americium ion electronic configuration. (orig.)