Towards high-valent uranium compounds from metallacyclic uranium(IV) precursors.

Treatment of [NaUN*(C,N)(2)] [N* = N(SiMe(3))(2); C,N = CH(2)SiMe(2)N(SiMe(3))] with I(2) led to the formation of the larger metallacycle [UN*(N{SiMe(3)}SiMe(2)CH(2)CH(2)SiMe(2)N{SiMe(3)})I] resulting from U-C cleavage and C-C coupling. Reaction of [NaUN*(O,N)(2)] [O,N = OC(=CH(2))SiMe(2)N(SiMe(3))] with I(2) afforded the U(V) complex [Na{UN*(O,N)(2)}(2)(μ-I)] which was converted into the mononuclear azido derivative [NaUN*(O,N)(2)(N(3))]. This latter was not transformed into the neutral U(VI) derivative in the presence of I(2) but afforded [U(V)(N{SiMe(3)}SiMe(2)C{CHI}O)(2)I(THF)], resulting from a cascade of addition, substitution and protonolysis reactions.