The trivalent lanthanoid formamidinates, [Yb2(DFForm)4F2(py)2] ⋅ CH3CN (1) (DFForm=N,N′‐bis(2,6‐difluorophenyl)formamidinate), and [La6(DFForm)8F8O(CH3CN)2] ⋅ 6CH3CN (2) have been prepared from redox transmetallation (RT) reactions employing lanthanoid metals and silver formamidinate (AgDFForm) in CH3CN. C−F activation was observed in both reactions. The structure of 1 is a fluorine bridged dimer with two seven‐coordinate ytterbium metal ions. Surprisingly the lanthanum complex is a trivalent cage with an unexpected central oxygen atom. [La6(DFForm)8F8O(CH3CN)2] ⋅ 6CH3CN (2) formed a 15 membered ring cage of six La atoms, eight F and one O at the centre. There are three different La3+ ions in 2 with two different coordination numbers. All the La atoms are coordinated by four bridging fluorides and the central oxygen.