Synthesis, Structural Characterization of a New Ethylenediammonium Hydrogenophosphate Salt

The integration of organic species with inorganic units result to the formation of hybrid materials that combine the complementary properties of both components. These organo-inorganic systems are of great interest because of their potential synergistic behavior. In materials chemistry, the aim objective is to develop simple and efficient synthetic strategies that combine the rigidity and stability of inorganic frameworks with the versatility and tunability of organic moieties. In this work, we report structural characterization of a new organic–inorganic hybrid salt, ethylenediammonium hydrogenophosphate, [H₃N–CH₂–CH₂–NH₃][HPO₄], which was synthesized under aqueous reflux conditions. The compound was characterized by single-crystal X-ray diffraction and FT-IR spectroscopy. It crystallizes in the monoclinic system, space group P2₁/c, with unit cell parameters a = 7.4896(8) Å, b= 11.7702(12) Å, c = 8.0080(8) Å. The asymmetric unit consists of one ethylenediammonium dication and one monohydrogenophosphate anion. Structural analysis reveals that the crystal packing is governed by an extended three-dimensional network of N–H···O and O–H···O hydrogen bonds, which link the cations and anions into a robust supramolecular framework. FT-IR spectroscopy confirms the presence of protonated amine groups together with hydrogenophosphate units, consistent with the crystallographic findings. These results demonstrate the ability of ethylenediamine to promote the formation of stable hydrogen-bonded phosphate frameworks. Owing to their structural robustness and hydrogen-bonding features, such hybrids may represent promising candidates for potential applications in proton-conducting systems and functional optical materials.