Quantum-Chemical Calculations of the Enthalpy of Formation for 5/6/5 Tricyclic Tetrazine Derivatives Annelated with Nitrotriazoles

This paper presents the study of the calculated physicochemical properties of new high-energy 5/6/5 tricyclic structures, which are 1,2,3,4- or 1,2,4,5-tetrazines, fused with a pair of 1H-1,2,4-, 4H-1,2,4-, or 1H-1,2,3-triazoles. The values of the enthalpy of formation in the gaseous phase are determined by high-performance quantum-chemical calculations (in the Gaussian 09 program package) using various methods for solving the stationary Schrödinger equation, including G4, G4MP2, ωB97XD/aug-cc-pVTZ, CBS-APNO, CBS-QB3, CBS-4M, B3LYP/6-311+G(2d,p), and M062X/6-311+G(2d,p). The results of the calculations obtained by the methods of atomization and isogyric reactions are analyzed. Various calculation methods are compared in terms of accuracy and time consumption.