Thorium Oxo and Sulfido Metallocenes: Synthesis, Structure, Reactivity, and Computational Studies

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• 作者：Wenshan Ren ; Guofu Zi ; De-Cai Fang ; Marc D. Walter
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：August 24, 2011
• 年：2011
• 卷：133
• 期：33
• 页码：13183-13196
• 全文大小：1480K
• 年卷期：v.133,no.33(August 24, 2011)
• ISSN：1520-5126

文摘

The synthesis, structure, and reactivity of thorium oxo and sulfido metallocenes have been comprehensively studied. Heating of an equimolar mixture of the dimethyl metallocene [畏⁵-1,2,4-(Me₃C)₃C₅H₂]₂ThMe₂ (2) and the bis-amide metallocene [畏⁵-1,2,4-(Me₃C)₃C₅H₂]₂Th(NH-p-tolyl)₂ (3) in refluxing toluene results in the base-free imido thorium metallocene, [畏⁵-1,2,4-(Me₃C)₃C₅H₂]₂Th鈺怤(p-tolyl) (4), which is a useful precursor for the preparation of oxo and sulfido thorium metallocenes [畏⁵-1,2,4-(Me₃C)₃C₅H₂]₂Th鈺怑 (E = O (5) and S (15)) by cycloaddition鈥揺limination reaction with Ph₂C鈺怑 (E = O, S) or CS₂. The oxo metallocene 5 acts as a nucleophile toward alkylsilyl halides, while sulfido metallocene 15 does not. The oxo metallocene 5 and sulfido metallocene 15 undergo a [2 + 2] cycloaddition reaction with Ph₂CO, CS₂, or Ph₂CS, but they show no reactivity with alkynes. Density functional theory (DFT) studies provide insights into the subtle interplay between steric and electronic effects and rationalize the experimentally observed reactivity patterns. A comparison between Th, U, and group 4 elements shows that Th⁴⁺ behaves more like an actinide than a transition metal.