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

The utility of [(C 5 Me 5 )(C 8 H 8 )U] 2 (μ-η 3:η 3 -C 8 H 8 ), 1, as a precursor to monoalkyl and monoaryl heteroleptic pentamethylcyclopentadienyl cyclooctatetraenyl U 4+ metallocene complexes, (C 5 Me 5 )(C 8 H 8 )UR (R = alkyl, aryl), has been explored. Complex 1 reacts with AgOTf (OTf = OSO 2 CF 3 ) to form [(C 5 Me 5 )(C 8 H 8 )U(μ-OTf)] 2, 2, which contains readily displaceable triflate ligands. Complex 2 reacts with KN(SiMe 3 ) 2, LiCH(SiMe 3 ) 2, LiPh, and Li[ i PrNC(Me)N i Pr] to form (C 5 Me 5 )(C 8 H 8 )U[N(SiMe 3 ) 2 ], 3, (C 5 Me 5 )(C 8 H 8 )U[CH(SiMe 3 ) 2 ], 4, (C 5 Me 5 )(C 8 H 8 )UPh, 5, and (C 5 Me 5 )(C 8 H 8 )U[ i PrNC(Me)N i Pr-κ 2 N, N ′], respectively. The insertion reactivity of 5 with tert -butyl isocyanide and the carbodiimide i PrN═C═N i Pr was investigated, and (C 5 Me 5 )(C 8 H 8 )U[η 2 -C(Ph)═N t Bu], 6, and (C 5 Me 5 )(C 8 H 8 )U[ i PrNC(Ph)N i Pr], 7, were isolated, respectively.