Solid‐State Preparation and Luminescence Investigation of Rare Earth Iodide Carbodiimide Nitrides RE 2 I(CN 2 )N (RE = La, Gd) and LaI(CN 2 )

New rare earth iodide carbodiimide nitride compounds with the composition RE 2 I(CN 2 )N (RE = La, Gd) were successfully synthesized by multilateral solid‐state metathesis reaction from RE triiodides, LiN and Li 2 (CN 2 ). The crystal structures of RE 2 I(CN 2 )N were refined from X‐ray powder diffraction data with the space group Cmmm . LaI(CN 2 ) was prepared from a mixture of LaI 3 and Li 2 (CN 2 ). The crystal structure was determined by X‐ray single‐crystal diffraction on a colorless crystal with the orthorhombic space group Cmcm . The luminescence investigation of Ce 3+ ‐doped LaI(CN 2 ) was carried out by excitation at 390 nm and reveals a broad emission band in the blue range of the visible spectrum.