R. N. Shchelokov

X-ray diffraction study of K3[UO2(C2O4)2(NCS)] · 3H2O

The single crystals of K3[UO2(C2O4)2(NCS)] · 3H2O were studied by X-ray diffraction. The compound crystallizes in the monoclinic system, space group P21/n, Z = 4, a = 10.673 Å, b = 12.041 Å, c = 13.856 Å, β = 110.18°, R = 0.0290. The basic structural units of the crystals of I are the island complex groups [UO2(C2O4)2NCS]3− corresponding to the crystal-chemical group AB012M1 (A = UO22+, B01 = C2O42−, M1 = NCS−) of uranyl complexes and connected into a three-dimensional framework through electrostatic interactions and through hydrogen bonds involving potassium ions and water molecules.

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.

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.