Hydrogen-bonded Supramolecular Association in Organic Acid-base Pyrimidine Salt and Hirshfeld Surface Analysis

Abstract

The present study deals with the crystal structure of organic salt, namely, 2-amino-4-methoxy-6-methylpyrimidinium 2-chlorobenzoate, synthesized by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction technique. The colourless crystal structure of salt belongs to the monoclinic crystallographic system with space group P21/c, Z = 4, and a = 7.3269 (3) Å, b = 25.2003 (10) Å, c = 7.9743 (3) Å, β = 112.795 (2) °. The pyrimidine moieties are protonated at one of the nitrogen atoms of the pyrimidine rings. The carboxylate group of the anions (hydrogen 2-chlorobenzoate) interacts with the protonated pyrimidine moiety through a pair of N–H···O hydrogen bonds resulting the complementary DDAA (D = donor and A = acceptor in hydrogen bonds) arrays of quadruple hydrogen-bonding patterns. The -COO-acceptor consistently seeks out the -N-H+ donor generating the most important intermolecular interaction by comparison with similar structures in the Cambridge Structural Database (CSD). The combination of the strong hydrogen bonding (N–H···O and C–H···O) and weak hydrogen bonding (π–π stacking) associations in the crystal packing led to the formation of the 3-Dimensional network structures. A detailed analysis of Hirshfeld surfaces and 2-D fingerprint plots facilitate a comparison of intermolecular interactions in the supramolecular architecture. An evaluation of the Hirshfeld surfaces confirm the importance of intermolecular interactions involving oxygen atoms as well as the π—π stacking interactions.