Intermolecular interactions were also revealed by the Atoms-in-Molecules (AIM) method , where the electron density (i) of the bond critical points (BCPs) connecting fragments through intermolecular bond paths serve as a measure of the interaction strength. In this way, covalent bonds, closed-shell interactions, and weak electrostatic interactions are characterized by ρi values of i0.10, i0.10-0.04, and i≤0.01 e/Bohr 3 , respectively . Furthermore, the signature of weak interactions were examined by the Independent Gradient Model (IGM) , which introduce the g inter descriptor that uniquely defines intermolecular interaction regions: g inter =| IGM,inter |-||, where  stands for the electron density gradient and  IGM,inter is an upper limit to  as defined by Lefebvre and co-workers . AIM, IGM (based on the Hirshfeld partition), CM5 charges, and wavefunction analyses were performed in Multiwfn3.7 .