Formation of Cocrystals between Alkali Triazine Tricarboxylates and Cyanuric Acid – Reactivity Considerations and Structural Characterization of the Adduct Phases M3[C3N3(CO2)3][C3N3O3H3]·H2O (M = K,Rb)

The reactivity of cyanuric acid towards alkali triazinetricarboxylates was investigated and the first triazine‐triazine adduct phases comprising alkali metal ions were synthesized and characterized by single‐crystal X‐ray diffraction and thermal analysis. An investigation of the reaction between the alkali triazine tricarboxylates M₃C₃N₃(CO₂)₃] · xH₂O (M = Li, Na, K, Rb, Cs) and cyanuric acid showed that the degree of ion transfer from triazine tricarboxylate to cyanuric acid increases gradually from the lithium to the cesium salt reflecting an increasing basicity of the triazine tricarboxylates.The reaction of potassium and rubidium triazine tricarboxylate dihydrate with cyanuric yielded the novel co‐crystalsK₃C₃N₃(CO₂)₃]C₃N₃O₃H₃] · H₂O ( 3a ) and Rb₃C₃N₃(CO₂)₃]C₃N₃O₃H₃] · H₂O ( 3b ). In comparison to metal free triazine‐triazine adduct phases in these compounds the assembly of molecules in the crystal is mainly determined by Coulomb interactions and only to a certain degree by hydrogen bonds and dispersive interactions. In the crystal the s‐triazine units exhibit a layered structure with triazine tricarboxylate and isocyanuric acid being arranged in zigzag strands within the layers and stacked in columns perpendicular to the layers. Thermal analysis revealed a quite weak cohesion between triazine tricarboxylate and cyanuric acid upon heating.