A novel method for synthesizing crystalline copper carbodiimide, CuNCN. Structure determination by X-ray rietveld refinement

Abstract

Well-crystallized copper carbodiimide, CuNCN, was synthesized by the slow oxidation of a copper(I) cyanamide precursor under aqueous conditions. The X-ray powder data evidence the orthorhombic system and space group Cmcm with a = 2.9921(1), b = 6.1782(1), c = 9.4003(2) Å, V = 173.769(5) Å3 and Z = 4. There is a strongly distorted octahedral Cu 2+ coordination reflecting a typical first-order Jahn-Teller effect, with interatomic distances of 4 x Cu-N = 2.001(2) Å and 2 x Cu-N = 2.613(3) Å; the NCN2- unit adopts the carbodiimide shape with C-N = 1.227(4) Å. Despite the formal d9 electron count of Cu2+, CuNCN exhibits a small temperature-independent paramagnetism and is likely to be a metallic conductor. © 2005 Verlag der Zeitschrift für Naturforschung.