- A cerium(IV)-carbon multiple bond
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Straightforward access to a cerium(IV)-carbene complex was provided by one-electron oxidation of an anionic ate cerium(III)-carbene precursor, thereby avoiding decomposition reactions that plague oxidations of neutral cerium(III) compounds. The cerium(IV)-carbene complex is the first lanthanide(IV)-element multiple bond and involves a twofold bonding interaction of two electron pairs between cerium and carbon. Copyright
- Gregson, Matthew,Lu, Erli,McMaster, Jonathan,Lewis, William,Blake, Alexander J.,Liddle, Stephen T.
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- Silyl-Phosphino-Carbene Complexes of Uranium(IV)
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Unprecedented silyl-phosphino-carbene complexes of uranium(IV) are presented, where before all covalent actinide–carbon double bonds were stabilised by phosphorus(V) substituents or restricted to matrix isolation experiments. Conversion of [U(BIPMTMS)(Cl)(μ-Cl)2Li(THF)2] (1, BIPMTMS=C(PPh2NSiMe3)2) into [U(BIPMTMS)(Cl){CH(Ph)(SiMe3)}] (2), and addition of [Li{CH(SiMe3)(PPh2)}(THF)]/Me2NCH2CH2NMe2 (TMEDA) gave [U{C(SiMe3)(PPh2)}(BIPMTMS)(μ-Cl)Li(TMEDA)(μ-TMEDA)0.5]2 (3) by α-hydrogen abstraction. Addition of 2,2,2-cryptand or two equivalents of 4-N,N-dimethylaminopyridine (DMAP) to 3 gave [U{C(SiMe3)(PPh2)}(BIPMTMS)(Cl)][Li(2,2,2-cryptand)] (4) or [U{C(SiMe3)(PPh2)}(BIPMTMS)(DMAP)2] (5). The characterisation data for 3–5 suggest that whilst there is evidence for 3-centre P?C?U π-bonding character, the U=C double bond component is dominant in each case. These U=C bonds are the closest to a true uranium alkylidene yet outside of matrix isolation experiments.
- Lu, Erli,Boronski, Josef T.,Gregson, Matthew,Wooles, Ashley J.,Liddle, Stephen T.
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- Uranium-carbon multiple bonding: Facile access to the pentavalent uranium carbene [U{C(PPh2NSiMe3)2}(Cl)2(I)] and comparison of UV=C and UIV=C bonds
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(Chemical Equation Presented) A straightforward oxidation strategy affords the first pentavalent uranium carbene complex, 2. Owing to the structural similarity of 1 and 2, it was possible for the first time to directly probe the differences in U=C bonding on oxidation of UIV to UV.
- Cooper, Oliver J.,Mills, David P.,McMaster, Jonathan,Moro, Fabrizio,Davies, E. Stephen,Lewis, William,Blake, Alexander J.,Liddle, Stephen T.
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supporting information; experimental part
p. 2383 - 2386
(2011/04/21)
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