Crystal structure of [UO₂(NH₃)₅]NO₃·NH₃

Abstract

The title compound, [UO2(NH3)5]NO3·NH3, contains a penta­gonal–bipyramidal [UO2(NH3)5]+ cation, a nitrate anion and an ammonia mol­ecule of crystallization.

A Dinuclear Uranium Complex [{UO2F2(NH3)}2(μ‐F)2]2− from Reaction of TlF and UO2F2 in Liquid Anhydrous Ammonia and Fluoride Ion Affinities for Some Uranyl(VI) Species [UO2Fx]2−x and [UO2Fx(NH3)5−x]2−x

“…The [{UO 2 F 2 (NH 3 )} 2 (μ‐F) 2 ] 2− anion ( C i ), shown in Figure 3, contains one symmetry‐independent U atom (2 i , 1) which is surrounded by seven atoms to form a pentagonal bipyramid‐like coordination sphere with the O atoms forming the tips. This coordination sphere is well known for uranyl(VI) cations [8–10,21] . The U≡O distances agree with 1.787(3) and 1.796(3) Å compared to 1.781 and 1.783 Å in the [{UO 2 F 2 (H 2 O)} 2 (μ‐F) 2 ] 2− anion and to 1.772(3) and 1.784(2) Å in the compound [UO 2 F 2 (NH 3 ) 3 ] 2 ⋅ 2NH 3 [8,23] .…”

“…This coordination sphere is well known for uranyl(VI) cations. [8][9][10]21] The U�O distances agree with 1.787(3) and 1.796(3) Å compared to 1.781 and 1.783 Å in the [{UO 2 F 2 (H 2 O)} 2 (μ-F) 2 ] 2À anion and to 1.772(3) and 1.784(2) Å in the compound [UO 2 F 2 (NH 3 ) 3 ] 2 • 2NH 3 . [8,23] Despite the coordination of one of the O atoms to a Tl + cation, we observe no significant lengthening of the U�O bond.…”

“…Besides these pseudo‐binary uranyl(VI) compounds UO 2 X 2 ( X =F, Cl, Br, I, OAc, $${{ 1/2 }}$$ SO 4 ) also the compound Cs[UO 2 (NO 3 ) 3 ] containing the complex [UO 2 (NO 3 ) 3 ] − anion has been reacted with excess aNH 3 in presence of UF 4 . Surprisingly, a reduction of U(VI) to U(V) was observed as the compound [UO 2 (NH 3 ) 5 ]NO 3 ⋅ NH 3 was obtained, containing a pentagonal bipyramidal [UO 2 (NH 3 ) 5 ] + monocation, [10] while the other reaction products remained unidentified.…”

Uranium Chemistry in liquid Ammonia: Compounds obtained by adventitious Presence of Moisture or Air

“…+ ions seems to be larger as the uranyl(V) compound [UO 2 (NH 3 ) 5 ]NO 3 • NH 3 containing only simple NH 3 ligands was obtained. [26] The aqueous chemistry of the uranyl(VI) ion has been investigated thoroughly due to its importance in nuclear waste treatment and recycling. Some compounds obtained from hydrolysis have been either structurally characterized or computationally predicted, [27][28][29][30][31][32][33][34][35][36][37][38][39] with the pentagonal-bipyramidal [UO 2 (H 2 O) 5 ] 2 + cation being the most important mononuclear species.…”

Disproportionation of the Uranyl(V) Coordination Complexes in Aqueous Solution through Outer-Sphere Electron Transfer

“…Crystal structures of [UO 2 (dpaea)]­X complexes were determined and these complexes are reported to be stable at the pH range of 7–10 and disproportionation is noted at the pH ≤ 6. An intriguing stable uranyl­(V) complex is the [UO 2 (NH 3 ) 5 ] + which forms when Cs­[UO 2 (NO 3 ) 3 ] and UF 4 are mixed together followed by the addition of liquid NH 3 ; the reaction is speculated to follow a comproportionation reaction scheme (U­(IV) + U­(VI) → 2U­(V)), but the clear mechanistic details are lacking . In addition, another inorganic uranyl­(V) complex experimentally characterized is the [UO 2 Cl 4 ] 3– , and this complex was reported to be stable in a room temperature ionic liquid solution [a mixture of 1-ethyl-3-methylimidazolium tetrafluoroborate and its chloride (EMI + BF 4 – /Cl + )] and single crystals were not isolated .…”