Uranium-Carbon Multiple Bonding: Facile Access to the Pentavalent Uranium Carbene [U{C(PPh2NSiMe3)2}(Cl)2(I)] and Comparison of UV=C and UIV=C Bonds
Uranium-Carbon Multiple Bonding: Facile Access to the Pentavalent Uranium Carbene [U{C(PPh2NSiMe3)2}(Cl)2(I)] and Comparison of UV=C and UIV=C Bonds
复制标题
DOI：
10.1002/anie.201007675
复制
发表时间：
2011-01-01
影响因子：
16.6
通讯作者：
Liddle, Stephen T.
中科院分区：
文献类型：
--
作者：
Cooper, Oliver J.;Mills, David P.;Liddle, Stephen T.
与d-嵌段金属-配体多重成键和反应的广泛研究相比，[1]相应的f-嵌段化学领域是不发达的.[2，3]对于铀，亚胺和氧代配合物占主导地位，但不是来自中性游离卡宾的铀卡宾很少.[3]第一个铀卡宾，[U(η5-C5H5)3(CHPMe2R)](R=Ph，I；[4]铀卡宾已在基质分离实验中被检测到，并与酮与UCl4/Li(汞)的反应有关。[6]最近，Ephritikhine等人。报道了一系列的铀卡宾，以[U{C(PPh2S)2}(BH4)2-(THF)2]，[7]为例，作为f-嵌段卡宾研究程序的一部分，[8]我们报道了同质的铀卡宾[U{C(PPh2NMes)2}2](1，Mes=2，4，6-三甲基苯基)。高价类似物以它们的不存在而引人注目，这与高氧化态铀氧和亚胺络合物的主导地位形成对比。[3，10]然而，五价铀化学最近重新活跃起来，[10]受到这一点和没有任何铀(V)卡宾的鼓励，我们通过氧化策略瞄准了五价铀卡宾。在这里，我们报道了第一个五价铀卡宾的简单合成、结构和反应活性，它首次允许在UV=C和UIV=C键之间进行直接比较。配合物1是由[UI3(THF)4]和[Li4{C(PPh2NMes)2}2]发生歧化反应得到的。[9]因此我们采用[UCl4(THF)3]，并用[Li4{C(PPh2NSiMe3)2}2][11]在甲苯/Et2O中处理它(方案1)。铀(IV)卡宾[U{C(PPh_2NSiMe_3)_2}(Cl)(μ-Cl)_2Li-(THF)_2](2)经四氢呋喃处理和重结晶后，以62%的产率分离为黄色板状化合物。
Compared to the extensive investigations of d-block metal–ligand multiple bonding and reactivity,[1] the corresponding field of f-block chemistry is underdeveloped.[2, 3] For uranium, imido and oxo complexes dominate, yet there is a paucity of uranium carbenes that do not derive from neutral free carbenes.[3]The first uranium carbenes,[U (η5-C5H5) 3 (CHPMe2R)](R= Ph, I; Me, II), were reported by Gilje et al.[4] Uranium carbenes have been detected in matrix isolation experiments,[5] and implicated in reactions of ketones with UCl4/Li (Hg).[6] Recently, Ephritikhine et al. reported a range of uranium carbenes, exemplified by [U {C (PPh2S) 2}(BH4) 2-(THF) 2],[7] and, as part of a program studying f-block carbenes,[8] we reported the homoleptic uranium carbene [U {C (PPh2NMes) 2} 2](1, Mes= 2, 4, 6-trimethylphenyl).[9] To date, all uranium carbenes with UÀC multiple bonds incorporate uranium (IV). Higher-valence analogues are notable for their absence, which contrasts to the dominance of high-oxidation-state uranium oxo and imido complexes.[3, 10] However, pentavalent uranium chemistry has been revitalized recently,[10] and encouraged by this and the absence of any uranium (V) carbenes we targeted a pentavalent uranium carbene by an oxidation strategy. Herein, we report the facile synthesis, structure, and reactivity of the first pentavalent uranium carbene, which permits direct comparisons between UV= C and UIV= C bonds for the first time. Complex 1 was prepared from a disproportionation reaction between [UI3 (thf) 4] and [Li4 {C (PPh2NMes) 2} 2].[9] We therefore employed [UCl4 (thf) 3] and treated it with [Li4 {C (PPh2NSiMe3) 2} 2][11] in toluene/Et2O (Scheme 1). The uranium (IV) carbene [U {C (PPh2NSiMe3) 2}(Cl)(μ-Cl) 2Li-(thf) 2](2) was isolated as yellow plates in 62% yield following workup and recrystallization from THF.[12] The molecular structure of 2, as determined by X-ray crystallography, is shown in Figure1a with selected bond