Mesoionic tetrazolium-5-aminides: Synthesis, Molecular and Crystal Structures, UV-Vis Spectra, and DFT Calculations

Tetrazolium-5-aminides have been prepared by tert-butylation of 5-aminotetrazole and its N-methyl derivatives by t-BuOH/HClO4 system followed by treatment of tetrazolium salts by alkali. These mesoionic compounds have been found to show higher reactivity of exocyclic N atom in comparison with 5-aminotetrazoles. They react with 1,2-dibromoethane and 5-(methylsulfonyl)-1-phenyl-1H-tetrazole and substitute bromine and methylsulfonyl groups giving tetrazolium salts or conjugate aminides. Obtained mesoionic tetrazoles have been characterized by elemental analysis, FT-IR, NMR and UV-Vis spectroscopy, TGA/DSC analysis and for 1,3-di-tert-butyltetrazolium-5-aminide, it’s N,N’-ethylene bridged bis-derivative and (1,3-di-tert-butyl-1H-tetrazol-3-ium-5-yl)(1-phenyl-1H-tetrazol-5-yl)amide by single crystal X-ray analysis. Structural and spectral features of tetrazolium-5-aminides are discussed by using quantum-chemical calculations.