Elucidating the crystal structures of heteronuclear salen complexes CuL-CdX2 with experimental and computational methods

Abstract

Two novel heteronuclear salen-type complexes, CuL1-CdCl2 and CuL2-CdI2, have been successfully synthesized and characterized. The characterization processes utilized single-crystal X-ray diffraction, elemental, and FT-IR analysis, revealing the structural properties of the complexes. In both complexes, the Cu(II) ion exhibited an approximate square planar geometry (CuN2O2), where the deprotonated phenoxide-type ligand L2− coordinated to form N2O2. Conversely, For CuL1-CdCl2, the Cd(II) ion displayed a trigonal prismatic geometry, surrounded by two chlorine atoms and four oxygen atoms. Intermolecular and intramolecular interactions within the complex were facilitated by CH···Cl, CH···N, and CH···O hydrogen bondings. For CuL2-CdCl2, the Cd(II) ion displayed a trigonal prismatic geometry, surrounded by two iodine atoms and four oxygen atoms. Intermolecular interactions within the complex were facilitated by weak CH···I hydrogen bonding, while the overall stability of the framework was ensured through weak π···π stacking interactions. According to the Hirshfeld surface analysis results, the H···H contacts constitute a large part of the total surface area for both complexes; this highlights the importance of hydrogen bond interactions in stabilizing the crystal arrangement. The theoretical analysis of the complexes was executed by using Becke's three-parameter hybrid functional for the exchange component and the Lee-Yang-Parr (LYP) correlation function with the LanL2DZ basis set to achieve the optimized geometrical parameters. The results showed that experimental and theoretical calculations were in agreement.