Uranium-carbon bond

Matson EM, Forrest WP, Fanwick PE, Bart SC. Synthesis and reactivity of trivalent Tp U(CH2Ph2)2(THF) insertion vs oxidation at low-valent uranium-carbon bonds. Organometallics. 2013 32 1484-1492. 

It is reasonable to postulate that the main driving force for the reaction of (MeC5H4)3U(t-Bu) with hexafluorobenzene is thermodynamic. A weak uranium-carbon bond and a carbon-fluorine bond have to be broken. This is offset by the formation of a strong uranium-fluorine bond and either a carbon-carbon or a carbon-hydrogen bond. As illustrated in equation 8, the uranium-fluorine bond energy can be estimated to be on the order of 150 kcal/mol based on known thermochemical data for uranium fluorides (21), The carbon-fluorine bond dissociation energy for hexafluorobenzene is reported to be 154 kcal/mol (17), The... 

Toumeux J-C, Berthet J-C, Cantat T, Thuery P, Mezailles N, Ephritikhme M (2011) Exploring the uranyl organometalhc chemistry from single to double uranium-carbon bonds. J Am Chem Soc 133 6162-6165. doi 10.1021/ja201276h... 

Cramer RE, Jeong JH, Gilje JW (1987) Uranium-carbon multiple bond chemistry. 9. The insertion of phenyl isocyanate into the uranium-carbon bond of Cp3U CHP(Ph)(R)(Me) to form Cp3U[(NPh)(0)CCHP(Ph)(R)(Me)]. Organometallics 6 2010-2012. doi 10.1021/ om00152a040... 

Bishomoallyl alcohols, via allyindium reagents, 9, 703 Bis(hydrostannation), in tin-carbon bond formation, 3, 814 Bis(imidazolyl) ligands, chromium complexes, 5, 359 Bis(imido) systems, with chromium(VI), as models, 5, 377 Bis(imido)tungsten complexes, synthesis, 5, 749 Bis(imido)uranium(VI) complexes, synthesis, 4, 216-217 Bis(imino)carbenes, with Zr(IV), 4, 798 Bis(iminooxazolidine) complexes, biaryl-bridged, with Zr(IV) and Hf(IV), 4, 811-812... 

The uranium-carbon multiple bond has an extensive insertion chemistry with polar unsaturated molecules including carbon monoxide, nitriles, isocyanides,and isocyanates. Metal carbonyls also insert into this bond to form metallaphosphoniumenolates, which undergo novel reactions... 

Uranium. Ephritikhine ha.s established that treatment of either cyclohexanone or benzophenone with UCI4 and Na/Hg affords the pinacol adduct in good yield (Eq. 3.26) [42]. The uranium benzopinacolate intermediate from the homocou-pling of benzophenone was characterized by X-ray crystallography. Mechanistic studies indicate that carbon-carbon bond formation proceeds via ketyl dimerization [43]. 

Treatment of U02C12(THF)3 in THF with 1 equiv. of Na[CH(Ph2P=NSiMe3)2] led to formation of an unusual red uranyl chloro-bridged dimer (70% yield) containing a uranium(vi)-carbon bond as part of a tridentate bis(imino-phosphorano)methanide chelate complex (Scheme 9). This was the first example of a uranyl-methine carbon bond. The methine carbon is displaced significantly from the uranyl equatorial plane.33... 

The high thermal stability of the metal-carbon bond in the actinide methyl derivatives suggests that a series of alkyl derivatives can be made. This does not prove to be the case. Reaction of C1M[N(SiMe3)2]3/ where M is thorium or uranium, with either ethyllithium or trimethylsilylmethyllithium at room temperature in diethyl ether yields the metallocycle (VI) and ethane or tetramethylsilane. A mechanism for this transformation, which involves a y-proton abstraction, is shown below. 

Prior to and during the Manhattan Project, considerable eflFort was directed toward the synthesis of volatile uranium alkyl compounds such as U( 2115)4 for use in isotope separation. These attempts were unsuccessful (8, 9) and it was assumed that the uranium alkyl bond was intrinsically unstable. Thus, for several decades the nature of the uranium-to-carbon linkage remained unexplored, and there was even some question as to whether such bonding could take place. 

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