Facile Reductive Silylation of UO₂²⁺ to Uranium(IV) Chloride

Abstract

General reductive silylation of the UO 2 2+ cation occurs readily in aone-pot, two-step stoichiometric reaction at room temperature to form uranium(IV) siloxides.Addition of two equivalents of an alkylating reagent to UO 2 X 2 (L) 2 (X = Cl, Br,I ,O Tf;L = triphenylphosphine oxide,2 ,2'-bipyridyl) followed by two equivalents of as ilyl (pseudo)halide,R 3 Si-X (R = aryl, alkyl, H; X= Cl, Br,I ,O Tf,S Ph), cleanly affords (R 3 SiO) 2 UX 2 (L) 2 in high yields.Support is included for the key step in the process,r eduction of U VI to U V .T his procedure is applicable to aw ide range of commercially available uranyl salts,silyl halides,and alkylating reagents.Under this protocol, one equivalent of SiCl 4 or two equivalents of Me 2 SiCl 2 results in direct conversion of the uranyl to uranium(IV) tetrachloride. Full spectroscopic and structural characterization of the siloxide products is reported.

Transformation of Metal–Organic Framework Secondary Building Units into Hexanuclear Zr-Alkyl Catalysts for Ethylene Polymerization

“…Me 3 SiCl was previously used to activate UO and CdOR bonds to form UCl and CdCl species in molecular systems. 38,39 We propose that the ZrOH species is first silylated to generate Zr-OSiMe 2c), and TEM images display clear lattice fringes with a distance of 1.72 nm, corresponding to the calculated d-spacing of 1.75 nm along the (200) planes (Figure 2d). N 2 sorption isotherms of ZrCl 2 -BTC at 77K gave a Brunauer−Emmett−Teller (BET) surface area of 1693 m 2 /g, slightly lower than those of Zr-BTC (1843 m 2 /g) and ZrOH-BTC (1779 m 2 /g), due to the increased SBU weight of ZrCl 2 -BTC (Figure S6, SI).…”

“…Zr. Me 3 SiCl was previously used to activate UO and CdOR bonds to form UCl and CdCl species in molecular systems. , …”

Structural Characterization and Redox Activity of a Uranyl Dimer and Transition-Metal Complexes of a Tetradentate BIAN Ligand

“…In order to better comprehend these fundamental properties, the characterization of lower-valent uranium species has become pertinent . Coordination chemistry of the early actinides consists largely of U­(VI) complexes bearing the linear uranyl [OUO] 2+ moiety, which is ubiquitous in nature due to the remarkable stability of its oxo groups. , This stability is one complication in removing uranium contamination from the environment, as the most prevalent species is the uranyl dication, which is highly soluble in aqueous settings. A two-electron reduction to less soluble U­(IV) species, as occurs in bioremediation, is thought to occur via functionalization of the oxo groups via a pentavalent (UO 2 + ) intermediate, but unfortunately, this mechanism is poorly understood and inorganic model systems are incomplete .…”

Synthesis and Characterization of a Series of U(IV) trans-bis(Wittig) Adducts Across the UX4 Halide Series

“…As compared to trans-UCl4(OPPh3)2, the trans-Cl-U-Cl bonds show a small bowing of 174.0(1)° and 176.8(1)° with the Cl-U-O bond angles ranging from 87.4(3)° to 93.9(3)°. 20 The most salient feature of the solid-state molecular structures of 1 Ph -XꞏC6H8 and 2 tBu -Xꞏn(o-DFB) is the uranium-carbon, U-CWittig, bond distance, which seemingly shows a sensitivity to the identity of the halide substituent with the U-CWittig bond generally shortening as the halide series is descended as follows: show a very slight elongation from UCl4(CH2PAr3)2 to UI4[CH2P( tBu Ar)3]2; however, the differences all fall well within the estimated standard deviations (esd) of the bond measures. Though, in all cases, the C1-P1 bond is significantly longer by ca.…”