Formation of Trivalent U–C, U–N, and U–S Bonds and Their Reactivity toward Carbon Dioxide and Acetone

Abstract

A family of uranium(III) complexes of the form Tp*2UX (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate, X = CCPh (2-CCPh), CCSiMe3 (3-CCSiMe 3 ), NHPh (4-NHPh), NHCH2Ph (5-NHCH 2 Ph), SPh (6-SPh)) have been synthesized in quantitative yields by protonation of the benzyl group Tp*2U(CH2Ph) (1-CH 2 Ph) with organic precursors. Full characterization of these complexes, which contain newly formed uranium–carbon, uranium–nitrogen, and uranium–sulfur bonds, was performed using 1H NMR and IR spectroscopies. These data along with the structural parameters of the uranium acetylide (2-CCPh) and uranium thiolate (6-SPh) species are reported. Treating the trivalent uranium acetylides and amides with 1 atm of carbon dioxide results in its insertion into the uranium–element bond to form the corresponding carboxylate or carbamate moiety in quantitative isolable yields. Reversible insertion of carbon dioxide (1 atm) into the uranium–sulfur bond of Tp*2U(SPh) (6-SPh) was also noted. The new family of CO2-inserted uranium(III) derivatives Tp*2UO2CX (X = CCPh (7-O 2 CCCPh), CCSiMe3 (8-O 2 CCCSiMe 3 ), NHPh (9-O 2 CNHPh), NHCH2Ph (10-O 2 CNHCH 2 Ph), SPh (11-O 2 CSPh)) has been characterized spectroscopically and, in the case of 7-O 2 CCCPh, crystallographically. The newly formed U–O bonds were cleaved by addition of trimethylsilyl halides, generating the monohalide derivative. Attempts to insert acetone into the uranium–carbon bonds of 1-CH 2 Ph and 2-CCPh or the uranium–nitrogen bond in 4-NHPh resulted exclusively in protonation of the benzyl ligand and isomerization to form a rare enolate complex Tp*2U(OC(CH3)CH2) (12-OC(CH 3 )CH 2 ). This complex has been fully characterized by 1H NMR and infrared spectroscopies as well as X-ray crystallography.

Synthesis of low-valent uranium fluorides by C–F bond activation

“…The U-N bond lengths, ranging from 2.542(4) to 2.739(3) Å, are in agreement with typical U-N bond lengths seen for bis-Tp* supported uranium(III) species. [12][13][14] As expected, the terminal U-F distance of 2.156(3) Å is shorter than the analogous U-X distances reported for Tp* 2 UCl (2.698 Å) and Tp* 2 UI (3.220 Å). To the best of our knowledge, this complex represents the first crystallographically characterized terminal uranium(III) fluoride.…”

Diazoalkane Reduction for the Synthesis of Uranium Hydrazonido Complexes

“…bibenzyl was noted, as determined by integration against a ferrocene internal standard. [12,13,[16][17][18] Compound 2 features a short U1-N41 (diazomethane Nα) bond length of 2.146(7) Å, which is indicative of uranium-nitrogen mulwww.eurjic.org [20] commonly show longer U-N bonds. of the diazoalkane with the uranium(III) species Tp* 2 U(2,2Ј-bpy), which has a monoanionic bipyridine ligand.…”

Actinide‐Mediated Catalytic Addition of EH Bonds (E=N, P, S) to Carbodiimides, Isocyanates, and Isothiocyanates

“…[15] Hence,d eveloping atom-efficient, versatile catalytic systems for their preparation represents amajor challenge in the field of homogeneous catalysis,e specially because the respective metal catalyst is required to display at olerance toward functional groups and heteroatoms.Previous studies by Evans et al have shown that carbodiimides can effectively insert into the AnÀC(An = Th,U)bond of Cp* 2 An(CH 3 ) 2 ,yielding mixed cyclopentadienyl actinide amidinate complexes in high yield. [20] It should be noted, however, that these actinide species have not been investigated as part of acatalytic process. [20] It should be noted, however, that these actinide species have not been investigated as part of acatalytic process.…”

“…[21] Thus,w ed ecided to investigate the substantial question whether the stoichiometric reactivity toward carbodiimides displayed by organometallic actinide complexes [16,20] can be incorporated into ac atalytic cycle by the protonolytic cleavage of the AnÀN bond, formed by the insertion of the carbodiimide,w ith different families of R À E À H( E= N, P, S; R= alkyl, aryl, H) moieties,y ielding actinide amido,p hosphido,a nd sulfide intermediates.T herefore,w es et out to study the catalytic activity of actinide coordination complexes toward different families of heterocumulene systems and REH moieties,i n which Ei san ucleophilic element, expanding the scope of accessible products.Owing to the high activity,selectivity,and tolerance toward functional groups displayed by 1 in the Tishchenko reaction, [21] the thorium compound 1 was applied for all further catalytic studies with heterocumulenes presented herein. (1)],can be used as an active catalyst for the dimerization of aldehydes,displaying high catalytic activity and selectivity toward the formation of asymmetrically substituted esters.…”