M. Lance

Triscyclopentadienyl uranium thiolates and selenolates

Triscyclopentadienyl uranium (IV) thiolates were prepared by two principal methods namely (1) substitution of the chloride group of [U(cp)3(Cl)] (cp = η-C5H5) by Sr− and (2) oxidation of the trivalent precursors [U(cp)3(THF)] (THF = tetrahydrofuran), [U(C5H4SiMe3)3] and [U(C5H4tBu)3] with the disulfide RSSR (R = Me, Et, iPr, tBu or Ph).Similar treatment with MeSeSeMe afforded [U(cp)3(SeMe)] and [U(C5H4SiMe3)3(SeMe)]. The crystal structure of [U(cp)3(SMe)] was determined. Several reactions ofthese complexes are described, namely cleavage of the U-S bond by acidic substrates or iodine, insertion of Cs2 and CO2 into the U-S bond, and reduction into the corresponding U(III) anions. The synthesis, structure and reactivity of the thiolate compounds are compared with those of the alkoxide analogues.

Triaquabis(nitrato-O, O')(2,2':6', 2-terpyridine-κ3N)gadolinium(III) nitrate

Gadolinium nitrate forms a complex with terpyridine at the interface between an aqueous solution of the metal cation and a chloroform solution of the organic ligand. The title complex, [Gd(terpy)(NO 3 ) 2 (H 2 O) 3 ]NO 3 (terpy = terpyridine, C 15 H 11 N 3 ), is ten-coordinate and its coordination polyhedron can be described as a distorted bicapped square antiprism. The coordinated nitrates are bidentate. The three water ligands form hydrogen bonds in the lattice.

Pentaaquadioxouranium(VI) triflate–18-crown-6

The uranyl ion in pentaaquadioxouranium(VI) bis(trifluoromethanesulfonate)-1,4,7,10,13,16-hexaoxacyclooctadecane, [UO 2 (H 2 O) 5 ](CF 3 SO 3 ) 2 .C 12 H 24 O 6 , is equatorially surrounded by five O atoms from water molecules. The CF 3 SO 3 - ions and the crown ether are not part of the uranyl coordination polyhedron but are linked to the U atom via hydrogen bonds

Reaction of uranium tetrachloride with trimethylsilylcyclopentadiene: crystal structure of a dichloromethane adduct of [{U(cp)2(μ-Cl)}3 (μ3-Cl)2][{U(cp)Cl2}2(μ-Cl)3] (cp = η = C5H5)

Abstract The uranium tetrachloride reacts in dichloromethane with 1 and 3 equivalents of trimethylsilylcyclopentadiene to give [U(cp)Cl 3 ] ( 1 ) and [U(cp) 3 Cl] ( 3 ) respectively (cp = η-C 5 H 5 ). The title compound 2 was isolated from the reaction of UCl 4 with 2 equivalents of the silylated cyclopentadiene. Complex 2 is in equilibrium with 1 and 3 in refluxing dichloromethane.

Inclusion complex between uranyl and an azacrown; structure of [UO2(18-azacrown-6)]2+.2CF3SO3−

The title complex, (1,4,7,10,13,16-hexaazacyclooctadecane)dioxouranium bis(trifluoromethylsulfonate), [UO 2 (C 12 H 30 N 6 )] 2+ .2CF 3 SO 3 - , is composed of [UO 2 (18-azacrown-6)] 2+ and CF 3 SO 3 - ions. In the cation, the uranyl is bonded to the six N atoms of the crown in a hexagonal bipyramidal coordination. This is the first reported uranyl hexaazacrown inclusion complex

An Inclusion Complex of Uranyl in a Diazacrown: (Diaza-18-crown-6)2+.2CF3SO3− and [UO2(diaza-18-crown-6)]+.CF3SO3−

The structures of two compounds involving the macrocycle 1, 4, 10, 13-tetraoxa-7, 16-diazacyclooctadecane (diaza-18-crown-6, C 12 H 26 N 2 O 4 ) are reported. In 1, 4, 10, 13-tetraoxa-7, 16-diazoniacyclooctadecane bis(trifluoromethanesulfonate), C 12 H 28 N 2 O 4 2+ .2CF 3 SO 3 − , (I), the two N atoms are protonated, resulting in a ring conformation different to that of the neutral crown. The second compound, dioxo[1, 4, 10, 13-tetraoxa-7, 16-diazocyclooctadecanido(1 −)]uranium trifluoromethane-sulfonate, [UO 2 (C 12 H 25 N 2 O 4 )]CF 3 SO 3 , (II), is composed of [UO 2 (diaza-18-crown-6)] + cations and CF 3 SO 3 − anions. The linear uranyl moiety is included into the macrocycle with hexagonal-bipyramidal coordination geometry; one of the N atoms is deprotonated and the two N atoms are thus at different distances from the U atom and have different geometries

(H4-Hexaaza-18-crown-6)4+.4CF3SO3− and its Hydrated Form

The structures of the two compounds reported here involve the tetraprotonated form of the macrocycle 1,4,7,10,13,16-hexaazacyclooctadecane (hexaaza-18-crown-6 = C 12 H 30 N 6 ) : (H 4 -hexaaza-18-crown-6).4(trifluoromethanesulfonate), C 12 H 34 N 6 4+ .4CF 3 SO 3 - , and the hydrated form (H4-hexaaza-18-crown-6).4(trifluoromethanesulfonate).H 2 O, C 12 H 34 N 6 4+ .4CF 3 SO 3 - .H 2 O. In both compounds, the conformation of the macrocycle is g + g - g + g - g + g - . The counterions and the water molecule are hydrogen bonded to protonated N atoms.

A Complex Between Uranyl Trifluoromethanesulfonate Hydrate and Benzo-15-crown-5

In triaquadioxobis(trifluoromethanesulfonato)uranium-(VI)-benzo-15-crown-5 (1/2), [UO 2 (CF 3 SO 3 ) 2 (H 2 O) 3 ].2C 14 H 20 O 5 , the uranyl ion is in a pentagonal pseudo-planar equatorial environment, consisting of two O atoms from two trifluoromethanesulfonate (triflate) ions and three from water molecules. The coordination of CF 3 SO 3 - is particularly notable owing to the poor coordinating character of this ion. Two molecules of benzo-15-crown-5 are hydrogen bonded to the water molecules (one water molecule bridging) without any direct interaction with the uranyl moiety.

Bis(N,N-dimethylformamide)(μ-sulfato)dioxouranium(VI)

In the title compound, [UO 2 (SO 4 )(C 3 H 7 NO) 2 ], the uranyl ion is in a pentagonal pseudo-planar equatorial environment, comprising two dimethylformamide and three sulfate O atoms. The uranyl ions are bridged by sulfate groups, giving rise to an infinite chain structure, i.e. catena-poly[(NN-dimethylformamide)dioxouranium-μ-sulfato-O,O:O]. Two of the sulfate O atoms are bonded to the same uranyl ion in a coordination mode previously not observed in uranyl sulfates.