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A Comprehensive Study Concerning the Synthesis, Structure, and Reactivity of Terminal Uranium Oxido, Sulfido, and
Tongyu Li1, Dongwei Wang1, Yi Heng1
1Department of Chemistry, Beijing Normal University, Beijing 100875, China.
Abstract:
Terminal uranium oxido, sulfido, and selenido metallocenes were synthesized, and their reactivity was comprehensively studied. Heating of an equimolar mixture of [η5-1,2,4-(Me3Si)3C5H2]2UMe2 (2) and [η5-1,2,4-(Me3Si)3C5H2]2U(NH-p-tolyl)2 (3) in the presence of 4-dimethylaminopyridine (dmap) in refluxing toluene forms [η5-1,2,4-(Me3Si)3C5H2]2U═N(p-tolyl)(dmap) (4), which is a useful precursor for the preparation of the terminal uranium oxido, sulfido, and selenido metallocenes [η5-1,2,4-(Me3Si)3C5H2]2U═E(dmap) (E = O (5), S (6), Se (7)) employing a cycloaddition-elimination methodology with Ph2C═E (E = O, S) or (p-MeOPh)2CSe, respectively. Metallocenes 5-7 are inert toward alkynes, but they act as nucleophiles in the presence of alkylsilyl halides. The oxido and sulfido metallocenes 5 and 6 undergo [2 + 2] cycloadditions with isothiocyanate PhNCS or CS2, while the selenido derivative 7 does not. The experimental studies are complemented by density functional theory (DFT) computations.
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