“…Salt-like compounds containing extended pseudochalcogenide NCN 2À anions, adopting either the highly symmetric carbodiimide À N=C=N À form with D 1h symmetry [1,2] or the less symmetrical cyanamide N�CÀ N 2À form, [3,4] have been known since the preparation of calcium carbodiimide, CaNCN, as early as 1895. [2] More recently, a growing family of MNCN (M = Mg, Ca, Sr, Mn, Fe, Co, Ni and Cu) [1,2,5,6] and M 2 (NCN) 3 (M = Cr, Sc and Yb) [7][8][9] binaries have been reported which are all characterized by alternating layers of metal cations and NCN 2À anions.…”