Determination of Intermolecular Interactions of Nicotinamide Liganded Complexes of Co(II), Cu(II), Ni(II) and Zn(II) 4-Formilbenzoates by Hirshfeld Surface Analysis and Investigation of Interaction Energies.

CrystalExplorer program is a program that has been used frequently in the field of theoretical chemistry in recent years and its popularity has increased. First of all, Hirshfeld surface analysis of molecules can be done in this program. Thanks to Hirshfeld surface analysis, intermolecular interactions and their contributions to the crystal surface can be determined. In this study, Hirshfeld surface analyzes and energy frameworks of nicotinamide complexes of Co(II), Cu(II), Ni(II) and Zn(II) 4-formylbenzoate were investigated. Dnorm index, shape index, curvature index and 2D fingerprint graphs were examined for all complexes. In addition, the intermolecular interaction energies of the complexes were calculated using the CE-B3LYP/6-31G (d,p) and CEHF/3-21G energy models. As a result of all these, it was seen that the most important interaction in the four isostructured complexes was H...H interactions. 
According to Hirshfeld surface analysis and energy frameworks, O-H...O and N-H...O hydrogen bonds and π•••π stacking and C−H••π interaction energies are seen as the most important interaction types in the crystal structure.