58001-79-9Relevant academic research and scientific papers
Preparation and reactivity of the versatile uranium(IV) imido complexes U(NAr)Cl2(R2bpy)2 (R = Me, tBu) and U(NAr)Cl2 (tppo)3
Jilek, Robert E.,Tomson, Neil C.,Shook, Ryan L.,Scott, Brian L.,Boncella, James M.
, p. 9818 - 9826 (2014)
Uranium tetrachloride undergoes facile reactions with 4,4'-dialkyl-2,2'-bipyridine, resulting in the generation of UCl4(R2bpy)2, R = Me, tBu. These precursors, as well as the known UCl4 (tppo)2 (tppo = triphenylphosphine oxide), react with 2 equiv of lithium 2,6-di-isopropylphenylamide to provide the versatile uranium(IV) imido complexes, U(NDipp)Cl2 (L)n (L = R2bpy, n = 2; L = tppo, n = 3). Interestingly, U(NDipp)Cl2 (R2bpy)2 can be used to generate the uranium(V) and uranium(VI) bisimido compounds, U(NDipp)2X(R2bpy)2, X = Cl, Br, I, and U(NDipp)2I2 (tBu2bpy), which establishes these uranium(IV) precursors as potential intermediates in the syntheses of high-valent bis(imido) complexes from UCl4. The monoimido species also react with 4-methylmorpholine-N-oxide to yield uranium(VI) oxo-imido products, U(NDipp)(O)Cl2 (L)n (L = tBu2bpy, n = 1; L = tppo, n = 2). The aforementioned molecules have been characterized by a combination of NMR spectroscopy, X-ray crystallography, and elemental analysis. The chemical reactivity studies presented herein demonstrate that Lewis base adducts of uranium tetrachloride function as excellent sources of U(IV), U(V), and U(VI) imido species.
Reductive silylation of uranyl mediated by iminosemiquinone ligands
Coughlin, Ezra,Bart, Suzanne C.
, p. 783 - 787 (2019/07/19)
Stoichiometric silylation of the uranyl species, (dippisq)2UO2THF, which features two reduced iminosemiquinone ligands, is reported. These ligand radicals facilitate the reduction of uranium 6+ to 4+, which is accompanied by silylation of the uranyl moiety with two equivalents of Me3SiBr and release of the oxidized ligand. The intermediate, (Me3SiO)2UBr2(OPPh3)2, is isolated prior to U–O bond cleavage by further addition of Me3SiBr, producing UBr4(OPPh3)2. U–O bond scission can also be performed in a one-pot reaction, by treating (dippisq)2UO2THF with Me2SiCl2, forming UCl4(OPPh3)2 and polymeric silyl products, (O[dbnd]SiMe2)n, with concomitant loss of oxidized ligand. In each case, isotopic 18O labeling experiments highlight the incorporation of the uranyl oxygen atoms into the resulting siloxanes released in the reactions.
Facile Reductive Silylation of UO22+to Uranium(IV) Chloride
Kiernicki, John J.,Zeller, Matthias,Bart, Suzanne C.
supporting information, p. 1097 - 1100 (2017/01/18)
General reductive silylation of the UO22+cation occurs readily in a one-pot, two-step stoichiometric reaction at room temperature to form uranium(IV) siloxides. Addition of two equivalents of an alkylating reagent to UO2X2(L)2(X=Cl, Br, I, OTf; L=triphenylphosphine oxide, 2,2′-bipyridyl) followed by two equivalents of a silyl (pseudo)halide, R3Si-X (R=aryl, alkyl, H; X=Cl, Br, I, OTf, SPh), cleanly affords (R3SiO)2UX2(L)2in high yields. Support is included for the key step in the process, reduction of UVIto UV. This procedure is applicable to a wide range of commercially available uranyl salts, silyl halides, and alkylating reagents. Under this protocol, one equivalent of SiCl4or two equivalents of Me2SiCl2results in direct conversion of the uranyl to uranium(IV) tetrachloride. Full spectroscopic and structural characterization of the siloxide products is reported.
