Cerium(III) and Uranium(IV) Complexes of the 2-Fluorophenyl Trimethylsilyl Amide Ligand: C–F → Ln/An Interactions that Modulate the Coordination Spheres of f-Block Elements

2-fluorophenyl trimethylsilyl amide, N(SiMe3)(C6H4F)− was shown to engage in stronger C–F → CeIII interactions than pentafluorophenyl trimethylsilyl amide, N(SiMe3)(C6F5)−, through a comparative study of the CeIII model complexes Ce[N(SiMe3)(C6H4F)]3 (1-F1) and Ce[N(SiMe3)(C6F5)]3 (1-F5). The presence of multiple C–F → UIV interactions led to complexes 2-X (X = Cl, C≡CPh, OMe) with threefold geometries, featuring a trigonal pyramidal UN3Cl core in the solid-state structures. Density functional theory calculations were applied to 2-Cl to investigate the strength of the C–F → UIV interactions and the influence of such interactions on resulting geometries.