Uranium-carbon multiple bond

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... 

Cooper OJ, Mills DP, McMaster J, Moro F, Davies ES, Lewis W, Blake AJ, Liddle ST (2011) Uranium-carbon multiple bonding facile access to the pentavalent uranium carbene [U C (PPh2NSiMe3)2 (C1)2(1)] and comparison of U(V)=C and U(IV)=C bonds. Angew Chem Int Ed 50 2383-2386. doi 10.1002/anie.201007675... 

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... 

Cramer RE, Riga KT, Gilje JW (1984) U-C multiple bonds. 4. Addition of coordinated carbon mtmoxide across a uranium-carbon multiple bond. J Am Chem Soc 106 7245-7247. doi 10.1021/ja00335a065... 

The chemistry of U and Th, usually similar, differs in the reaction of CpsAnCI with Li(CH2CH2PPh2) (Cramer et al. 1995a) (scheme 4). A methine carbon is coordinated with a multiple bond character in the U derivative, while with thorium two ylide anions chelate to the metal through methylene groups. This has been related to the difference in the electronic configuration of uranium(IV) and thorium(IV). 

Metals with a d f" configuration, group 3 metals, lanthanides, and actinides, are usually classified as f-elements. Because they are highly electropositive, they form polarized bonds with p-block elements, including carbon and nitrogen. So far, two reaction mechanisms have been established for d f metals cr-bond metathesis, a 2o—2o process, and 1,2-addition, a [2ct—2jt] process (2cr stands for the two electrons involved in the transition state that come from a tr bond and 2jt indicates the two electrons involved in the transition state that come from a Jt bond) (Scheme 1). " Oxidative addition, another type of reaction mecharusm that is common for late transition metals, is absent from the chemistry of rare-earth metals or actinides. This is partly because of the lack of valence electrons, i.e., a d electronic configuration however, even for uranium, which has multiple accessible oxidation states, no genuine oxidative addition reactivity has been reported. The subject of C—H bond activation mediated by f-elements has been dis-cussed by several recent reviews. ... 

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