Ab initio calculations of the structures and energies of gas phase isomeric C3N4 molecules

Ab initio calculations, including electron correlation, have been performed with split-valence plus polarization basis sets for isomeric C3N4 gas phase structures. The minimum energy configuration at the MP2(FC)/6-31G∗ level of theory is a linear chain rather than the tricyanoamine structure suggested in the literature. The latter, a planar structure, is predicted to lie 8.55 kcal mol−1 higher in energy, while a pyramidal configuration is 5.13 kcal mol−1 above the planar isomer. This is the first reported comparison of the possible gas phase C3N4 isomers, which could be important to the current efforts in the production of the crystalline material β-C3N4.