Synthesis and Experimental Studies on Supramolecular Synthons of Aminoguanidinium Carboxylates: A Case Study of π‐HoleBonded Carbon Bonding via Theoretical Approaches

Abstract

AbstractNew supramolecular salts of aminoguanidinium with mono and di‐carboxylic acids (formate and maleate respectively) have been prepared and their crystal structures were solved using single crystal X‐ray diffraction analysis. A crystal packing of both the ion pair assemblies are organized via various weak intermolecular interactions including N−H…O, O−H…O, C−H…O and N−H…N etc., hydrogen bonds and form 2D and 3D assemblies. The supramolecular viewpoint of the titled ion‐pair assemblies are discussed interms of strong hydrogen bonded ring motifs generated between the aminoguanidininium and carboxylates and the homo synthons of aminoguanidine retained in these solid state assemblies. Interestingly both the ion pair assemblies are supported by the π‐hole utilized carbon bonding (C…O, C…N &C…C) interactions. As compared to aminoguanidinium formate assembly, in amminoguanidinium hydrogenmaleate, π‐hole utilized carbon bonding interactions were sustained between the cation and anion pair which affords the spatial arrangement for stacking the cation and anion through electrostatic interaction. In this respect, π‐ hole interactions are function as a structure directing self‐assembled force and regulate the aminoguandinium hydrogen maleate assembly. Apart from the X‐ray diffraction studies, the geometrical parameters, interaction energy, its energy component contribution (LMOEDA analysis) and also the properties of weak interactions including carbon bonding present in the synthesized aminoguanidinium carboxylates assembly were analyzed systematically through wave functional analysis with MP2/6‐31++g(d,p) level of theory. The role of hydrogen bonding and carbon bonding confirmation and their strength in terms of crystal packing were summarized through various theoretical calculations such as Atoms In Molecules (AIM), Hirshfeld surface analysis, NCI plot and Natural Bonding Orbital analysis (NBO).