Crystal structures of products from the BBr3-promoted de-methyl-ation of 3-(meth-oxymeth-yl)-6-phenyl-1,2,4,5-tetra-zine.

Abstract

The BBr₃-promoted de-methyl-ation of 3-(meth-oxy-meth-yl)-6-phenyl-1,2,4,5-tetra-zine, C₁₀H₁₀N₄O, resulted in the alcohol (6-phenyl-1,2,4,5-tetrazin-3-yl)methanol, C₉H₈N₄O, and the bromide 3-(bromo-meth-yl)-6-phenyl-1,2,4,5-tetra-zine, C₉H₇BrN₄. All three compounds were analysed by nuclear magnetic resonance (NMR) spectroscopy in solution and by single-crystal X-ray diffraction using non-spherical scattering factors for structure refinement. The substrate as well as the corresponding bromide form π-π inter-actions between anti-parallel stacks of mol-ecules. In contrast, due to the inter-molecular hydrogen bonds present, which lead to the formation of a bent dimer, the alcohol forms only very weak parallel π-π stacks. Corresponding O-H⋯N hydrogen bonds are established between the hy-droxy group and an N atom of a neighbouring tetra-zine mol-ecule, an only rarely explored structural feature of 1,2,4,5-tetra-zines.