Complexes triflates de l’uranium

Abstract

Uranium triflate complexes. We review here the different preparations of uranium triflates that we have developed in the course of these last years in our laboratory. Protonation of 〚U〛–R and 〚U〛–NR 2 (R = alkyl) bonds with pyridinium triflate constitutes a general and efficient route towards triflate complexes. This method is very suitable for the preparation of organometallic compounds such as U(Cp) 3(OTf), U(Cp) 2(OTf) 2(py), U(Cp*) 2(OTf) 2, and U(Cot)(OTf) 2(py), which have been crystallographically characterised. The homoleptic species U(OTf) n ( n = 3, 4) are easily prepared by heating a mixture of uranium turnings or UH 3 in triflic acid. By adjusting the temperature to 120 or 180 °C, either U(OTf) 3 or U(OTf) 4 is isolated. Treatment of UO 3 with pure or aqueous solution of triflic acid leads to the non-solvated uranyl triflate UO 2(OTf) 2, which is more conveniently obtained by heating a suspension of UO 3 in triflic anhydride. This reactant is an excellent dehydrating agent and enables the preparation of UO 2(OTf) 2 and Ce(OTf) 4 from the hydrated starting materials.