Synthesis, Structure, and Reactivity of the Uranium Bipyridyl Complex [{η⁵-1,2,4-(Me₃Si)₃C₅H₂}₂U(bipy)]

Abstract

Reduction of [{η5-1,2,4-(Me3Si)3C5H2}2UCl2] (1) using potassium graphite (KC8) in the presence of 2,2′-bipyridine forms the uranium bipyridyl metallocene [{η5-1,2,4-(Me3Si)3C5H2}2U(bipy)] (2) in good yield, which was studied by various techniques. Complex 2 constitutes an excellent starting material for further reactions with small molecules for which two dominant reaction patterns emerge: (a) in the presence of CuI, Ph2E2 (E = S, Se), organic azides, diazenes, diazoalkanes, and CS2, complex 2 delivers a {η5-1,2,4-(Me3Si)3C5H2}2U(II) fragment. (b) In contrast, C–C bond coupling occurs when 2 is exposed to the thio-ketone Ph2CS, the aldehyde p-MePhCHO, the ketones Ph2CO and (CH2)5CO, and the seleno-ketone (p-MeOPh)2CSe to yield [{η5-1,2,4-(Me3Si)3C5H2}2U{(bipy)(Ph2CS)}] (12), [{η5-1,2,4-(Me3Si)3C5H2}2U{(bipy)(p-MePhCHO)}] (13), [{η5-1,2,4-(Me3Si)3C5H2}2U{(bipy)(Ph2CO)}] (14), [{η5-1,2,4-(Me3Si)3C5H2}2U{(bipy){(CH2)5CO}}] (15), and [{η5-1,2,4-(Me3Si)3C5H2}2U{(bipy){(p-MeOPh)2CSe}}] (16), respectively. On the contrary, the imido complex [{η5-1,2,4-(Me3Si)3C5H2}2U═NCHPh(C10H7N2)] (17) is isolated from the reaction of 2 with PhCN.