Access routes to carbon nitride CxNy. Examples at the turning point between molecular chemistry and solid chemistry.

The synthesis of beta-C3N4, predicted from ab initio calculations, seems di fficult owing to the stability of the N-2 molecule easily formed when high temperatures are involved in the preparation process. Using a high pressure process (P = 3 GPa) with organic precursors (5-azacytosine, 2-amino-4,6-di chloro-1,3,5-triazine) without solvent, a brown-orange solid was prepared. X-ray diffraction, infra-red spectroscopy and chemical titration show the f ormation of carbon nitride compounds CxNy. The knowledge of chemical mechan isms reveals new prospects about the synthesis of carbon nitride C3N4. (C) 1999 Academie des sciences/Editions scientifiques et medicales Elsevier SAS .