Supramolecular Assembly and Structural Insights of 2,4,6-triaminopyrimidinium bis(3,5-dinitrosalicylato) Diaquamagnesate(II) Dihydrate

Abstract

The monomeric magnesium complex, C₄H₈N₅⁺[Mg(C₇H₂N₂O₇)₂(H₂O)₂]·2 H₂O, crystallizes in a triclinic P-1 space group. In this structure, Mg(II) ion adopts an octahedral geometry. The coordination sphere around the metal center is formed by four oxygen atoms from two bidentate 3,5-dinitrosalicylate anions (DNS) in the equatorial plane, while two oxygen atoms from coordinated water molecules occupy the axial positions. Extensive hydrogen bonding stabilizes the crystal structure with the non-coordinated 2,4,6-triaminopyrimidinium cation (TAP) generating primary ring motifs such as R₂²(8) and R₂³(8), which extend into a complex three-dimensional hydrogen-bonded network. Coordinated and non-coordinated water molecules play a crucial role in maintaining the supramolecular framework by engaging in N–H…O, O–H…O and O–H…N hydrogen bonding interactions. Additionally, π–π stacking interactions contribute to the stabilization of the structure. These cooperative non-covalent interactions not only strengthen the crystal packing but also contribute to the overall stability of the supramolecular architecture, making this complex a potential candidate for future studies in crystal engineering and molecular assembly.