Synthesis, Crystal Structure Analysis and DFT Calculation of 1-Benzoyl-3,6-diphenyl-1,4- dihydro-1,2,4,5-tetrazine

The new title compound, 1-benzoyl-3,6-diphenyl-1,4-dihydro-1,2,4,5-tetrazine (C21H16N4O, Mr = 340.38), has been prepared and its crystal structure can not be confirmed by the results of MS, elemental analysis, IR spectrum and 1H NMR spectrum, but determined by X-ray diffraction. The title compound crystallizes in an orthorhombic space group P212121 with a = 7.1100(19), b = 12.115(3), c = 19.884(6), V = 1712.7(8)3, Z = 4, Dc = 1.320 g/cm3, F(000) = 712, μ = 0.085 mm-1, MoKa radiation (λ = 0.71073), R = 0.0334 and wR = 0.0845 for 2254 observed reflections with I > 2σ(I). X-ray diffraction analysis reveals that the central tetrazine adopts an unsymmetrical boat conformation. According to the bond lengths of tetrazine ring, the molecule should be 1,4-dihydro-1,2,4,5-tetrazine, rather than 1,2-dihydro-1,2,4,5-tetrazine. The crystal structure is stabilized mainly by intermolecular N–H···O hydrogen bonds.