Extending the Chemistry of the Uranyl Ion:  Lewis Acid Coordination to a UO Oxygen

Abstract

Treatment of the thf adduct UO2(NCN)thf (NCN = [(Me3SiN)CPh(NSiMe3)]) (1) with 2 equiv of B(C6F5)3 provides UO{OB(C6F5)3}(NCN)2 (2) the first example of a neutral uranyl complex exhibiting Lewis basic behavior. The crystal structure of 2 shows a U=O-B interaction with an elongated U=O bond (1.898(3) A). Raman spectroscopy suggests weakening of the O=U=O bonding, giving the lowest reported symmetric stretching frequency for a monomeric uranyl complex, nu1 = 780 cm-1. The borane can be selectively removed using PMe3 to give the coordinatively unsaturated UO2(NCN)2 (3) or using tBuNC to provide UO2(CNBut)(NCN)2 (4), the first example of an isonitrile coordinated to uranium.

η2‐Iminoacyl and η2‐Acyl Monocyclopentadienyl Tantalum Complexes Bearing Oxo and Oxo‐Borane Ligands

“…All the values of the bond lengths and angles of compound 2d are very close to the corresponding bond lengths and angles found for the parent compound [TaCp*Cl{η 2 -C(Me)=NAr}(O)] [10] except for the Ta [ [21][22][23][24][25][26][27][28][29][30][31] The Ta-O bond in 2d is longer than that in the oxo-borane compound [TaCp*Cl 2 {O·B(C 6 F 5 ) 3 }] [21] [1.784(2) Å]. This bond length is similar to the lower end of the range of Ta-O bond lengths for compounds with Ta-O-Ta bridges (1.82-2.10 Å) [32][33][34][35] and with terminal Ta-OH bonds (1.85-1.97 Å).…”

“…[10,11] The versatility and potential applications of all these results determined by the R and X substituents of the imido complexes [TaCp*MeX(NR)] led us to extend our studies to similar insertion reactions of CNR and CO into the Taalkyl bonds of the related oxo-borane compounds [TaCp*X 2 {O·B(C 6 F 5 ) 3 }] that have recently been isolated. [21] Results and Discussion [21][22][23][24][25][26][27][28][29][30][31] and the 1 H NMR spectra with the monosubstitution of only one of the alkyl ligands. These pale yellow complexes are air and thermally stable in solution.…”

“…The Ta have values that are normally seen for these types of compounds. [21][22][23][24][25][26][27][28][29][30][31] The whole set of angles and bond lengths of the [Ta-(η 2 -acyl)] group is in line with compounds of this type [1] and is similar to those found in the other two tantalum-acyl complexes for which X-ray structures are known, [TaCp*Me{η 2 -C(CH 2 CMe 2 Ph)=O}{N(2,6-Me 2 C 6 H 3 )}] [39] and [TaCp*Cl 3 {η 2 -C(CH 2 CMe 3 )=O}]. [40] However, in the particular case of the isostructural imido derivative [TaCp*Me{η The insertion of a second CNAr or CO molecule into these new acyl and iminoacyl oxo-borane complexes was not observed, in contrast with the behaviour observed for the analogous tert-butyl imido complexes.…”

Reduction and selective oxo group silylation of the uranyl dication

“…Examples include atypical Lewis base behaviour of the uranyl dioxo group towards alkali metals in the solid state 13,14 , and the formation of an unusual O=U=O→B(C 6 F 5 ) 3 adduct involving significant and asymmetric U=O bond lengthening 15 . Photolysis of uranyl phosphine oxide complexes in the presence of alcohols results in two-electron reduction and the formation of U(IV) alkoxides, via the highly oxidizing The X-ray single-crystal structure of 3 ( Fig.…”

Synthesis, Spectral and Electrochemical Studies of Complex of Uranium(IV) with Pyridine-3-Carboxylic Acid

“…We cannot ignore the importance of research on behavior of this metal in biosystems. A score of publications have been surfaced on the complexation tendencies of uranium(VI) with different biological ligands [3,4]. The aim of this work is to examine the interaction of uranium, in its (IV) oxidation state, with a ligand of biological significance i.e.…”