Synthesis and reactivity of U(IV) and U(V) bis(metallacycle) complexes
Jean-Claude Berthet, Olivier Bénaud, Pierre Thuéry, Michel Ephritikhine

The LCCEF has been developing the amide chemistry for a long time due to the great chemical opportunities afforded by the NR2 ligands. In particular, the bis(trimethylsilyl)amide ligand (N* = N(SiMe3)2), ubiquitous in coordination chemistry, is able to stabilize metal centres in their lowest and highest oxidation states and can be substituted with proton acidic molecules, so that bis(trimethylsilyl)amide compounds are valuable starting materials for inorganic and organometallic syntheses. In the presence of a base the “MXN*” complexes are often transformed into metallacycles [M(κ2(C,N)−CH2SiMe2N{SiMe3})] following γ-CH deprotonation and HX elimination.


Formation of compound 1 from UCl4 proved facile however strongly dependent on the nature of the solvent. If the U−N bonding proved relatively inert, the U−C bond readily inserted CO to give 2 and CO2 to afford the corresponding (O,N) derivative. Attempts at the oxidation of 1 and 2 with iodine to form U(V) compounds, revealed distinct behaviours, leading to a novel U(IV) mono metallacycle 3 or the U(V) derivative 4.

These compounds displayed interesting chemistry in particular with the cyanide  and azide ions.


  1. The bis metallacyclic anion [U(N{SiMe3}2)(CH2SiMe2N{SiMe3})2]
    O. Bénaud, J.-C. Berthet, P. Thuéry, M. Ephritikhine, Inorg. Chem., 2010, 49, 8117

  2. O. Bénaud, J.-C. Berthet, P. Thuéry, M. Ephritikhine, Chem. Commun., 2011, 47, 9057
  3. Iodide, azide, and cyanide complexes of (N,C), (N,N), and (N,O) metallacycles of tetra- and pentavalent uranium
    O. Bénaud, J.-C. Berthet, P. Thuéry, M. Ephritikhine, Inorg. Chem., 2011, 50, 12204

Contact: Jean-Claude Berthet.

#2073 - Màj : 15/04/2016



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