Theoretical study on the structures and stabilities of the isomers of N6H6

Forty-eight possible isomers of N6H6 have been investigated at the B3LYP/6-311++G∗∗ and G3B3 levels. The results show that heats of formation of all isomers are positive and A2-3 is the lowest and C2 is the highest. In addition, the energies and the heats of formation of the ring-shaped isomers are higher than those of the chain-shaped isomers. Among the ring-shaped isomers, the four-membered ring isomers have the highest heat of formation and the five-membered ring isomers have the lowest. For six-membered ring isomers, only the chair-shaped isomers are stable. Among all those chain-shaped isomers, the ones which have N-N bond and its length is in the range of NN double bond can improve the stability of the compounds.