Deciphering non-covalent interactions in unprecedented binuclear copper complex: Spectroscopic, Hirshfeld surface and DFT investigation

Binuclear Cu(II) complex derived from taurine and 2-hydroxy-4-methoxybenzaldehyde adduct was synthesised and characterised by X-ray crystallography, spectroscopic, Hirshfeld surface and DFT studies. The complex crystallises in monoclinic system with I 2/a space group. A theoretical study of the Cu (II) complex is performed with unrestricted density functional method at the level of B3LYP/ LANL2DZ/6-311 G (d, p) and a comparison between the experimental and simulated results were conducted. As predicted by the experiment, the computed results support distorted pyramidal geometry at metal centre. Non-covalent interactions primarily H-bonding and II-II stacking close contacts were observed at the intramolecular and intermolecular levels of the complex. An analysis of the FMO parameters reveals less reactivity and stability of complex. A high HOMO energy value and interatomic charge transfer has taken place with the Schiff base ligand. Furthermore, MEP used for predicting reactive sites clearly shows this complex is void of electrophilic reaction site. This complex has been subjected to NBO analysis to determine its hyperconjugation and therefore stability. The NBO analysis revealed the delocalization of charge within the molecule. Based on Hirshfeld surface analysis, there is evidence for a wide range of interactions and a significant contribution from several non-covalent interactions to crystal packing.