A Comprehensive Study Concerning the Synthesis, Structure, and Reactivity of Terminal Uranium Oxido, Sulfido, and Selenido Metallocenes

摘要

Terminal uranium oxido, sulfido, and selenido metallocenesweresynthesized, and their reactivity was comprehensively studied. Heatingof an equimolar mixture of [& eta;(5)-1,2,4-(Me3Si)(3)C5H2](2)UMe2 (2) and [& eta;(5)-1,2,4-(Me3Si)(3)C5H2](2)U(NH-p-tolyl)(2) (3) in the presence of 4-dimethylaminopyridine(dmap) in refluxing toluene forms [& eta;(5)-1,2,4-(Me3Si)(3)C5H2](2)U N(p-tolyl)(dmap) (4), which is a useful precursorfor the preparation of the terminal uranium oxido, sulfido, and selenidometallocenes [& eta;(5)-1,2,4-(Me3Si)(3)C5H2](2)U E(dmap) (E = O (5), S (6), Se (7)) employing a cycloaddition-eliminationmethodology with Ph2C E (E = O, S) or (p-MeOPh)(2)CSe, respectively. Metallocenes 5-7 are inert toward alkynes, but they act asnucleophiles in the presence of alkylsilyl halides. The oxido andsulfido metallocenes 5 and 6 undergo [2+ 2] cycloadditions with isothiocyanate PhNCS or CS2, whilethe selenido derivative 7 does not. The experimentalstudies are complemented by density functional theory (DFT) computations.