| Abstract |
A new monoiodide U(III) complex anchored on a hexadentate dianionic 1,4,8,11-tetraazacydotetradecane-based bis(phenolate) ligand, [U(kappa(6)-\((ArO)-Ar-tBu2)(2)Me-2-cydam\)I] (1), was synthesized from the reaction of [UI3(THF)4] (THF = tetrahydrofuran) and the respective potassium salt K-2((ArO)-Ar-tBu2)(2)Me-2-cydam and structurally characterized. Reactivity of 1 toward one-, two-, and four-electron oxidants was studied to explore the reductive chemistry of this new U(III) complex. Complex 1 reacts with one-electron oxidizers, such as iodine and TlBPh4, to form the seven-coordinate cationic uranium(IV) complexes [U(kappa(6)-\((ArO)-Ar-tBu2)(2)Me-2-cyclam\)I][X] (X = I (2-I), BPh4 (2-BPh4)). The new uranium(III) complex reacts with inorganic azides to yield the pseudohalide uranium(IV) complex [U(kappa(6)-\(ArO)-Ar-tBu2)(2)Me-2-cyclam\)(N-3)(2)] (4) and the nitride-bridged diuraniurn(IV/IV) complex [(kappa(4)-\((ArO)-Ar-tBu2)(2)Me-2-cyclam\)(N-3)U(mu-N)I(kappa(5)-\ ((ArO)-Ar-tBu2)(2)-Me-2-cydam\)] (5). Two equivalents of [U(kappa(6)-\((ArO)-Ar-tBu2)(2)Me-2-cyclam\)I] (1) effect the four-electron reduction of 1 equiv of PhN=NPh to form the bis(imido) complex [U(kappa(4)-\((tBu2)Aro)(2)Me-2-cyclam\)(NPh)(2)] (6) and the U(IV) species 2-I. Moreover, the hemilability of the hexadentate ancillary ligand ((ArO)-Ar-tBu2)(2)Me-2-cyclam(2-) allows to perform the reductive cleavage of azobenzene with an unprecedented formation of a trans-bis(imido) complex. The complexes were characterized by NMR spectroscopy, and all the new uranium complexes were structurally authenticated by single-crystal X-ray diffraction. |
