Synthesis and Insertion Chemistry of Monoalkyl and Monoaryl Uranium(IV) Heteroleptic Metallocene Complexes

The utility of [(C5Me5)(C8H8)U]2(μ-η3:η3-C8H8), 1, as a precursor to monoalkyl and monoaryl heteroleptic pentamethylcyclopentadienyl cyclooctatetraenyl U4+ metallocene complexes, (C5Me5)(C8H8)UR (R = alkyl, aryl), has been explored. Complex 1 reacts with AgOTf (OTf = OSO2CF3) to form [(C5Me5)(C8H8)U(μ-OTf)]2, 2, which contains readily displaceable triflate ligands. Complex 2 reacts with KN(SiMe3)2, LiCH(SiMe3)2, LiPh, and Li[iPrNC(Me)NiPr] to form (C5Me5)(C8H8)U[N(SiMe3)2], 3, (C5Me5)(C8H8)U[CH(SiMe3)2], 4, (C5Me5)(C8H8)UPh, 5, and (C5Me5)(C8H8)U[iPrNC(Me)NiPr-κ2N,N′], respectively. The insertion reactivity of 5 with tert-butyl isocyanide and the carbodiimide iPrNCNiPr was investigated, and (C5Me5)(C8H8)U[η2-C(Ph)NtBu], 6, and (C5Me5)(C8H8)U[iPrNC(Ph)NiPr], 7, were isolated, respectively.