A new class of unique quinoidal-like imidazoliumyl tetrazinides: synthesis, structure, and mechanism

Abstract

A series of 6-oxo-3-(1,2,4,5-substituted-1H-imidazol-3-ium-3-yl)-3,6-dihydro-1,2,4,5-tetrazin-3-ides (3a–3z, 3aa–3ak) was synthesized with medium to good yield by the reaction of 3,6-dichloro-1,2,4,5-tetrazine with a variety of substituted imidazoles in the presence of trace water in solvents. The quinoidal-like structure of these compounds was demonstrated via spectroscopic methods, X-ray diffraction techniques, and computational chemistry. Additionally, water–¹⁸O was used to prove that the oxygen in tetrazinone comes from the water in solvents via high-resolution mass spectrometry (HRMS). Moreover, a possible mechanism of aromatic nucleophilic substitution is proposed.