Formation of a Ce(Ⅳ) Oxo Complex via Inner Sphere Nitrate Reduction

摘要

Reaction of Ce(NO_3)_3(THF)_4 with Li_3(THF)_3(NN'_3) (NN'_3 = N(CH_2CH_2NR)_3, R = Si~tBuMe_2) in Et_2O, in the presence of 12-crown-4, results in the formation of [Li(12-crown-4)][(NN'_3)Ce(O)] (1) in 36% yield. This transformation proceeds via formation of a Ce(Ⅲ) nitrate intermediate, [Li(12-crown-4)]-[(NN'_3)Ce(κ~2-O_2NO)] (2), which undergoes inner sphere nitrate reduction. In addition, reaction of 1 with ~tBuMe_2SiCl results in the formation of (NN'_3)Ce-(Osi~tBuMe_2) (3), confirming the nucleophilic character of its oxo ligand. Natural bond orbital and quantum theory of atoms-in-molecules data reveal the Ce-O interaction in 1 to be significantly covalent, and strikingly similar to analogous U-O bonding.