10-Ethyl-4-oxo-2,3,4,10-tetrahydropyrimido[4,5-b]quinolin-2-iminium 4-toluenesulfonate: a polarized electronic structure in the cation and a hydrogen-bonded sheet structure

In the title compound, C13H13N4O+ center dot C7H7O3S- , the bond distances within the cation provide evidence for the delocalization of the positive charge in a manner reminiscent of guanidinium cations. Three independent N-H center dot center dot center dot O hydrogen bonds link the ions into centrosymmetric four-ion aggregates, and these are further linked into sheets by a single C-H center dot center dot center dot O hydrogen bond. This study shows how a single hydrogen bond can link centrosymmetric entities into a continuous sheet structure.