CHNO isomers and derivatives – a computational overview

Abstract

The full chemical space of the CHNO isomers and their related deprotonated CNO⁻ anions is described for the first time in terms of both the minimum energy structures and interconversions among them at the state-of-the-art multireference CASSCF(6,6)/MRACPF/def2-TZVP or single-reference DLPNO-CCSD(T)/def2-TZVPP levels. The electronic structure of all isomers is analyzed using several bond-strength-related descriptors, such as bond orders (WBI and MBO), atoms-in-molecules-derived properties and relaxed force constants, as well as via natural bond orbital (NBO) analysis. Destabilization of the cyclic oxazirine isomer is explained by its high computed ring-strain energy. Cyclotrimers of the most stable acyclic CHNO isomers are also reported.