Department of Chemistry, University of California , Irvine, California 92697-2025, United States.
J Am Chem Soc. 2017 Mar 8;139(9):3387-3398. doi: 10.1021/jacs.6b10826. Epub 2017 Feb 27.
The Th complex, (CMe)Th, has been isolated despite the fact that tris(pentamethylcyclopentadienyl) complexes are highly reactive due to steric crowding and few crystallographically characterizable Th complexes are known due to their highly reducing nature. Reaction of (CMe)ThMe with [EtNH][BPh] produces the cationic thorium complex [(CMe)ThMe][BPh] that can be treated with KCMe to generate (CMe)ThMe, 1. The methyl group on (CMe)ThMe can be removed with [EtNH][BPh] to form [(CMe)Th][BPh], 2, the first cationic tris(pentamethylcyclopentadienyl) metal complex, which can be reduced with KC to yield (CMe)Th, 3. Complexes 1-3 have metrical parameters consistent with the extreme steric crowding that previously has given unusual (CMe) reactivity to (CMe)M complexes in reactions that form less crowded (CMe)M-containing products. However, neither sterically induced reduction nor (η-CMe) reactivity is observed for these complexes. (CMe)Th, which has a characteristic EPR spectrum consistent with a d ground state, has the capacity for two-electron reduction via Th and sterically induced reduction. However, it reacts with MeI to make two sterically more crowded complexes, (CMe)ThI, 4, and (CMe)ThMe, 1, rather than (CMe)Th(Me)I. Complex 3 also forms more crowded complexes in reactions with I, PhCl, and AlMe, which generate (CMe)ThI, (CMe)ThCl, and (CMe)ThMe, 1, respectively. The reaction of (CMe)Th, 3, with H forms the known (CMe)ThH as the sole thorium-containing product. Surprisingly, (CMe)ThH is also observed when (CMe)Th is combined with 1,3,5,7-cyclooctatetraene. [(CMe)Th][BPh] reacts with tetrahydrofuran (THF) to make [(CMe)Th(THF)][BPh], 2-THF, which is the first (CMe)M of any kind that does not have a trigonal planar arrangement of the (CMe) rings. It is also the first (CMe)M complex that does not ring-open THF. [(CMe)Th][BPh], 2, reacts with CO to generate a product characterized as [(CMe)Th(CO)][BPh], 5, the first example of a molecular thorium carbonyl isolable at room temperature. These results have been analyzed using density functional theory calculations.
尽管三（五甲基环戊二烯基）配合物由于空间位阻而具有高反应性，并且由于其高度还原性质，已知的结晶学上可表征的钍配合物很少，但（CMe）Th 仍被分离出来。（CMe）ThMe 与 [EtNH][BPh] 反应生成阳离子钍配合物 [(CMe)ThMe][BPh]，可与 KCMe 处理生成 (CMe)ThMe，1。（CMe）ThMe 上的甲基可被 [EtNH][BPh] 除去以形成 [(CMe)Th][BPh]，2，这是第一个阳离子三（五甲基环戊二烯基）金属配合物，可被 KC 还原生成 (CMe)Th，3。配合物 1-3 的测度参数与之前在形成较少拥挤的（CMe）M 产物的反应中赋予（CMe）M 配合物异常（CMe）反应性的极端空间位阻一致。然而，这些配合物既没有观察到空间诱导还原，也没有观察到（η-CMe）反应性。（CMe）Th 具有与 d 基态一致的特征 EPR 光谱，可通过 Th 和空间诱导还原进行两电子还原。然而，它与 MeI 反应生成两个空间位阻更大的配合物（CMe）ThI，4 和（CMe）ThMe，1，而不是（CMe）Th（Me）I。配合物 3 也与 I、PhCl 和 AlMe 反应生成更拥挤的配合物，分别生成（CMe）ThI、（CMe）ThCl 和（CMe）ThMe，1。（CMe）Th，3 与 H 反应生成已知的（CMe）ThH 作为唯一含钍产物。令人惊讶的是，当（CMe）Th 与 1,3,5,7-环辛四烯结合时，也观察到（CMe）ThH。[(CMe)Th][BPh] 与四氢呋喃（THF）反应生成 [(CMe)Th(THF)][BPh]，2-THF，这是第一个没有（CMe）环的三角平面排列的任何类型的（CMe）M。它也是第一个不打开 THF 的（CMe）M 配合物。[(CMe)Th][BPh]，2，与 CO 反应生成一种特征为 [(CMe)Th(CO)][BPh]，5 的产物，这是可在室温下分离的第一个分子钍羰基化合物。这些结果已使用密度泛函理论计算进行了分析。
