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 difficult 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-dichloro-1,3,5-triazine) without solvent, a brown-orange solid was prepared. X-ray diffraction, infra-red spectroscopy and chemical titration show the formation of carbon nitride compounds CxNy. The knowledge of chemical mechanisms reveals new prospects about the synthesis of carbon nitride C3N4. (C) 1999 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.