Groenewold Gary S, Cossel Kevin C, Gresham Garold L, Gianotto Anita K, Appelhans Anthony D, Olson John E, Van Stipdonk Michael J, Chien Winnie
Department of Chemical Sciences, Idaho National Laboratory, 2525 North Fremont Avenue, Idaho Falls, ID 83415-2208, USA.
J Am Chem Soc. 2006 Mar 8;128(9):3075-84. doi: 10.1021/ja0573209.
Gas-phase complexes containing dioxouranium(V) cations (UO(2)) ligated with two or three sigma-donating acetone ligands reacted with dioxygen to form UO(2)(A)(2,3)(O(2)), where A is acetone. Collision-induced dissociation studies of UO(2)(A)(3)(O(2)) showed initial loss of acetone, followed by elimination of O(2), which suggested that O(2) was bound more strongly than the third acetone ligand, but less strongly than the second. Similar behavior was observed for complexes in which water was substituted for acetone. Binding of dioxygen to UO(2) containing zero, one, or four ligands did not occur, nor did it occur for analogous ligated U(IV)O(2) or U(VI)O(2) ions. For example, only addition of acetone and/or H(2)O occurred for the U(VI) species UO(2)OH, with the ligand addition cascade terminating in formation of UO(2)OH(A)(3). Similarly, the U(IV) species UOOH added donor ligands, which produced the mixed-ligand complex UOOH(A)(3)(H(2)O) as the preferred product at the longest reaction times accessible. Since dioxygen normally functions as an electron acceptor, an alternative mode for binding dioxygen to the cationic U(V)O(2) center is indicated that is dependent on the presence of an unpaired electron and donor ligands in the uranyl valence orbitals.
含有二氧铀（V）阳离子（UO(2)）且与两个或三个σ-供体丙酮配体相连的气相配合物与氧气反应生成UO(2)(A)(2,3)(O(2))，其中A为丙酮。对UO(2)(A)(3)(O(2))的碰撞诱导解离研究表明，最初会失去丙酮，随后消除O(2)，这表明O(2)的结合比第三个丙酮配体更强，但比第二个丙酮配体弱。对于用水取代丙酮的配合物也观察到了类似的行为。氧气与含有零个、一个或四个配体的UO(2)不发生结合，对于类似的连接的U(IV)O(2)或U(VI)O(2)离子也不发生结合。例如，对于U(VI)物种UO(2)OH，仅发生丙酮和/或H(2)O的添加，配体添加级联反应最终形成UO(2)OH(A)(3)。同样，U(IV)物种UOOH添加供体配体，在可达到的最长反应时间下，生成混合配体配合物UOOH(A)(3)(H(2)O)作为优选产物。由于氧气通常作为电子受体，表明存在一种将氧气与阳离子U(V)O(2)中心结合的替代模式，该模式取决于铀酰价轨道中未成对电子和供体配体的存在。
