Influence of the 1,3-Bis(trimethylsilyl)cyclopentadienyl Ligand on the Reactivity of the Uranium Phosphinidene [η⁵-1,3-(Me₃Si)₂C₅H₃]₂U(═P-2,4,6-^<i>i</i>Pr₃C₆H₂)(OPPh₃)

Abstract

At ambient temperature [η5-1,3-(Me3Si)2C5H3]2U(Cl)Me (3) reacts with 2,4,6-iPr3C6H2PHK in toluene in the presence of Ph3PO to yield the Lewis base supported terminal uranium phosphinidene metallocene [η5-1,3-(Me3Si)2C5H3]2U(═P-2,4,6-iPr3C6H2)(OPPh3) (4), whose structure and reactivity were probed. When it is treated with conjugated alkynes and diazabutadienes, compound 4 acts as a masked synthon for the divalent uranium fragment [η5-1,3-(Me3Si)2C5H3]2UII to give [η5-1,3-(Me3Si)2C5H3][η5-1-(CH2Me2Si)-3-(Me3Si)C5H3]U[(1-(2,4,6-iPr3C6H2)-2,5-Ph2C4HP] (7) and [η5-1,3-(Me3Si)2C5H3]2U[N(p-tolyl)CH(P-2,4,6-iPr3C6H2)CHN(p-tolyl)] (8), respectively. Nevertheless, in the presence of internal alkynes and various heterounsaturated molecules such as imines, carbodiimides, isothiocyanates, aldehydes, nitriles, isonitriles, and organic azides complex 4 affords metallaheterocycles, sulfido, oxido, and imido complexes in good yields. Furthermore, when it is exposed to the diazene PhN═NPh, complex 4 converts to the four-membered heterocycle [η5-1,3-(Me3Si)2C5H3]2U[N(Ph)P(2,4,6-iPr3C6H2)N(Ph)] (12) in good yield.