A Gaussian-3 investigation is carried out to examine the isomers of N-7 clusters. Twelve species are found, five of which are reported for the first time, including the most stable isomer, I. Isomer I, with C, symmetry, consists of a five-membered ring and an N-2 side-chain. Natural bond orbital analysis is also carried out to study the bonding of the isomers. It is found that the stability of some of the more stable isomers is enhanced by conjugation or hyperconjugation.