Electrophilic Ln(III) Cations Protected by C–F → Ln Interactions and Their Coordination Chemistry with Weak σ- and π‑Donors

A homoleptic cerium­(III) amide complex, Ce­(NPhF2)3 (1-Ce) (PhF = pentafluorophenyl), in an unusual pseudo-trigonal planar geometry featuring six C–F → Ce interactions was prepared. The C–F → Ln interactions in solution were evident by comparison of the 19F NMR shifts for the paramagnetic 1-Ce with those of the 4f0 lanthanum­(III) analogue. Coordination of weak σ- and π-donors, including ethers and neutral arene molecules, was achieved by the reversible displacement of the weak C–F → Ce interactions. Computational studies on Ce­(NPhF2)3 and Ce­(NPhF2)3(η6-C6H3Me3) provide information on the F → Ce interactions and Ce−η6-arene bonding.