Unprecedented Cyclic Isomer of Triazenes: A Computational Identification

摘要

abstract_textpIsomerism is very important in chemistry. Over the past 65 years, the energy-rich N3R3 family has received considerable attention both experimentally and computationally. Up to now, four isomeric types of N3R3 have been identified, i.e., triazenes I, triimides II, iso-triazenes III, and cyclo-triazanes IV. In this work, via the composite CBS-QB3 study on the isomers and transition states of N3H3-the simplest N3R3 system, we unexpectedly found a new structural type V, which contains a N-3 threemembered ring with one nitrogen-nitrogen dative bond in the ring (i.e., cyclic ammonia-nitrene interaction). Of all the N3H3 isomers, V lies the highest in energy (78.7 kcal/mol above the global triazene) and possesses a relatively low conversion barrier 8.9 kcal/mol. Yet quite promisingly, suitably choosing substituents can tune the rate-determining barrier of V to reach around 20 kcal/mol. Thus, synthesis of the newly found triazene isomer V is highly probable./p/abstract_text