A.V. Sergeev

Mixed ethylenediaminetetraacetic compounds of Uranium(IV) and Thorium(IV)

Abstract Recently some uranyl mixed complexes, containing ethylenediaminetetraacetic (edta) and other anions have been synthesized and crystal structure of the (CH 3 H 6 ) 4 [(UO 2 ) 2 edtaF 4 ] has been determined [1]. The edta group is shown to be a bridge hexadentate ligand with planar conformation of the NCN 2 CH 2 N fragment. As continuation of this work some other complexes of the U(IV) and Th(IV), namely M 4 [U(Th)edta(CO 3 ) 2 ]; M 4 [Uedta(c 2 O 4 ) 2 ]· 3H 2 O;M 3 [U(Th)edta·F 3 ]; M 2 [UedtaCl 2 ·4H 2 O]; U(Th)edta·6H 2 O (M CN 3 H + 6 ) were synthesized and their properties such as conductivity in water solutions, IR-spectra, thermostability were investigated. The structure of the (CN 3 H 6 ) 3 [UedtaF 3 ] and isomorphous (CN 3 H 6 ) 3 [ThedtaF 3 ] was determined by X-ray analysis. The coordination polyhedron of these compounds was shown to be a distorted square antiprism with the cap over one base (C.N.9). The edta group is hexadentate and ethylenediamine fragment has gosh-conformation. The structure is constituted by the separate complex [U(Th)edtaF 3 ] 3− anions and (CH 3 H 6 ) + cations. the hydrogen bonds NH⋯O and NH⋯F are between anions and cations.

Synthesis and structure of uranyl complexes with carboxylic acids and oxygen containing neutral ligands

Abstract Complexes [UO 2 AC 2 CH 3 CON(CH 3 ) 2 ] 2 , [UO 2 (C 6 H 5 COO)·2(CH 3 ) 2 SO 2 ] and [UO 2 AC 2 ·1.5CO(NH 2 ) 2 ] were obtained by the interaction of the aquadiacidouranyl complexes with the neutral ligands. Single crystal X-ray diffraction studies show that [UO 2 AC 2 CH 3 CON(CH 3 ) 2 ] 2 has dimeric structure and uranyl ion here is pentacoordinated. Crystal structure of the [UO 2 (C 6 COO) 2 ·2(CH 3 ) 2 SO) 2 ] is built of monomeric complexes where uranyl ion is hexacoordinated, and structure of the [UO 2 AC 2 ·1.5CO(NH 2 ) 2 ] is formed by the isolated complex [UO 2 AC 2·3CO(NH 2 ) 2 ] + cations and [UO 2 AC 3 ] − anions. Complex [UO 2 Pr·1.5CO(NH 2 ) 2 ] is built in the same way, uranyl ions are penta- and hexa-coordinated. The uranyl complex with dicarboxylic succinic acid and DMSO [UO 2 COOCH 2 COO·(CH 3 ) 2 SO] is built of chains where each acidoligand is bound in a bidentate way to one pentacoordinated uranyl ion, forming 4-membered cycle, and in a monodentate way to two other pentacoordinated uranyl ions. The crystal structure of the NH 4 [UO 2 Pr 3 ] is built of isolated complexes, each bidentate propionate ion forms a 4-membered cycle. The growth of the chains of monocarboxylic acids leads to predominance of the isolated forms of uranyl complexes.

Uranyl mixed compounds of the dioxalate series

Abstract By the X-ray diffraction method it has been established that the polyhedron of the aquo-dioxalate-uranylate ion [UO 2 (C 2 O 4 ) 2 (OH 2 )] 2− is a pentagonal bipyramid in which two oxalate groups close five-membered cycles. The pentacoordination of the uranyl group is also preserved in the complexes (CN 3 H 6 ) 3 [UO 2 (C 2 O 4 ) 2 F] and K(CN 3 H 6 ) 2 [UO 2 (C 2 O 4 ) 2 (NCS)]2H 2 O. The replacement of the aquo-group in the aquodioxalateuranylate ion by hydroxylaminate, N-methylhydroxylaminate and acetoxymate groups results in the formation of hexacoordinated compounds. (NH 4 ) 3 [UO 2 (C 2 O 4 ) 2 (NH 2 O)]H 2 O, (NH 4 )(CN 3 H 6 ) 2 [UO 2 (C 2 O 4 ) 2 (CH 3 NHO)]H 2 O, (CN 3 H 6 ) 3- [UO 2 (C 2 O 4 ) 2 (CH 3 ) 2 ]2H 2 O. It has been proved that in these compounds hydroxylamine, N-Methylhydroxylamine and acetoxyme are coordinated by the uranyl ion through the nitrogen and oxygen atoms forming a three-membered metallocycle as a result.