There are double-ring isomers with B-B bonds for (BN)_5 and (BN)6. It suggests that there exist nitrogen rich stable isomers for BN clusters.

• 当n=5、6时,(BN)_n团簇出现了存在B-B键的双环异构体,由此可预言氮化硼团簇中存在富N的稳定异构体。