Metal-urea complex - A precursor to metal nitrides

A novel and general route to synthesize various metal nitrides (AlN, CrN, and zeta-Fe2N) from metal-urea complexes is presented. These complexes, especially metal-urea chloride, have proved to be useful precursors to metal nitrides, because urea molecules construct a coordination sphere around the metal atom and form a stable structure, compared with the air-sensitive halide. Different anions in the second coordination sphere determine the reaction mechanism. The transformation from metal-urea chloride to nitride is thought to follow a nucleation-growth mechanism, while that from metal-urea nitrate is thought to follow a nitridation mechanism. We anticipate that this metal-urea complex will rind applications in the fabrication of other, more complex, nitrides.