Two-Dimensional Networks of Thiocyanuric Acid and Imine Bases Assisted by Weak Hydrogen Bonds

Abstract

Co-crystals of thiocyanuric acid (TCA) and five multitopic bases are reported, and their structures are compared. The adducts of all five co-crystals form two-dimensional hydrogen-bonded sheets that are either stacked or interpenetrated. Strong N–H···N hydrogen bonds between TCA and the N-heterocyclic bases are supplemented by pairs of longer, weaker C–H···S hydrogen bonds resulting in a motif reminiscent of the complementary triple hydrogen bond observed between imides and aminopyridines. TCA is observed to fulfill different roles in the adducts: a 3-fold node with triazine, a dimer junction exhibiting 4-fold connectivity with pyrazine, 2,7-diazapyrene, and DABCO, and an extended ribbon with 1,2-di(4-pyridyl)ethylene. The weak C–H···S hydrogen bonds are seen to be readily distorted to accommodate favorable packing arrangements in the adducts with pyrazine and DABCO, suggesting these weak C–H···S interactions possess a limited role in the direction of topology.