Triazinone tautomers: solid phase energetics

We investigate the relative stabilities, in the gas and solid phases, of three tautomers of hydroxytriazine. In order to study the solid state energetics, we generate a number of hypothetical crystal structures for each tautomer, which we then subject to lattice energy minimisation. In both the solid and gas phases, we find that hydroxytriazine (TOH) and the ortho-protonated triazinone tautomer (T1) are almost indistinguishable in energy and are significantly more stable than the para-protonated triazinone tautomer (T2). In the crystal structures, both the experimental ones of related molecules and the hypothetical ones generated for hydroxytriazine and its triazinone tautomers, we find the expected hydrogen bonding interactions. In addition, various motifs associated with pi-stacking are often found in the experimental structures.