Synthesis and Reactivity of the Uranium Bipyridyl Metallocene [η⁵-1,3-(Me₃C)₂C₅H₃]₂U(bipy)

Abstract

The addition of potassium graphite (KC8) to a mixture of [η5-1,3-(Me3C)2C5H3]2UCl2 (1) and 2,2′-bipyridine forms the uranium bipyridyl metallocene, [η5-1,3-(Me3C)2C5H3]2U(bipy) (2) in good yield, which is an excellent starting material for small molecule activation. Two major reactivity patterns have been identified for 2: (a) in the presence of a hydrazine derivative (PhNH)2, Ph2E2 (E = S and Se), AgF, alkynes, and a variety of heterounsaturated molecules, such as ketazine (Ph2C═N)2, diazenes, pyridine N-oxide, organic azides, and CS2, it acts as the synthetic equivalent for the [η5-1,3-(Me3C)2C5H3]2U(II) fragment. (b) Upon addition of thio-ketone Ph2CS; aldehyde p-BrPhCHO; ketones Ph2CO, (CH2)5CO, and 1-indanone; amidate PhCONH (p-tolyl); lactide; seleno-ketone (p-MeOPh)2CSe; imine (p-tolyl)2C═NH; ketazine (PhCH═N)2; and nitriles Me3CCN, PhCN, and C6H11CN, C–C coupling occurs to furnish [η5-1,3-(Me3C)2C5H3]2U[(bipy)(Ph2CS)] (20), [η5-1,3-(Me3C)2C5H3]2U[(bipy)(p-BrPhCHO)] (21), [η5-1,3-(Me3C)2C5H3]2U[(bipy)(Ph2CO)] (22), [η5-1,3-(Me3C)2C5H3]2U[(bipy){(CH2)5CO}] (23), [η5-1,3-(Me3C)2C5H3]2U[(bipy)(1-C8H8CO)] (24), [η5-1,3-(Me3C)2C5H3]2U[(bipy){PhCONH(p-tolyl)}] (25), {[η5-1,3-(Me3C)2C5H3]2U(bipy)(C3H4O2)}2 (26), [η5-1,3-(Me3C)2C5H3]2U[(bipy){(p-MeOPh)2CSe}] (27), [η5-1,3-(Me3C)2C5H3]2U[(bipy){(p-tolyl)2CNH}] (28), [η5-1,3-(Me3C)2C5H3]2U[(bipy)(PhCHNN═CHPh)] (29), [η5-1,3-(Me3C)2C5H3]2U[(bipy)(Me3CCN)] (31), [η5-1,3-(Me3C)2C5H3]2U[(C10H7N2)C(Ph)NH] (32), and [η5-1,3-(Me3C)2C5H3]2U[(C10H7N2)C(C6H11)NH] (33), respectively. However, from the reaction of 2 with thiazole, the dimeric sulfido complex {[η5-1,3-(Me3C)2C5H3]U[(C10H7N2)C(H)NCH═CHS]}2 (30) is isolated, while the addition of CuI to complex 2 induces a single-electron transfer process to yield the uranium(III) iodide complex [η5-1,3-(Me3C)2C5H3]2U(I)(bipy) (18).

Topics & Concepts