Structural and computational study of some new nano-structured Hg() compounds: a combined X-ray, Hirshfeld surface and NBO analyses

In this study, the synthesis of some new five coordinated mercury( ii ) complexes of a nitrogen donor Schiff base ligand is reported. The complexes were characterized by FT-IR, 1 H NMR, 13 C NMR, UV-visible, ESI-mass spectra and molar conductivity measurements. The nanoparticles of mercury( ii ) complexes were prepared by a sonochemical process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on spectral data, the general formula of HgLX 2 (X = Cl − , Br − , I − , N 3 − and SCN − ) was proposed for the complexes. The results of single crystal X-ray experiments for the HgLI 2 and HgL(SCN) 2 complexes confirm the spectral data and show distorted square-pyramidal geometries for metal centers. The packing of the molecules in the crystal structure is influenced by different intermolecular interactions such as N-H I, C-H I, C-H O and C-H π in HgLI 2 complex and C-H N, S N, C-H O and N O in the HgL(SCN) 2 complex. Hirshfeld surface analyses, especially d norm surface and fingerprint plots, were used for decoding intermolecular interactions in the crystal network. The results indicate that in both complexes, the anions connected to the metal center, aromatic rings and their nitro substituent play an important role in the construction of the 3D architecture. Optimized molecular geometries were derived from density functional theory (DFT) calculations and the results were compared with experimental ones. NBO analysis was applied for investigation of intra and inter molecular bonding and conjugative interaction in molecular systems. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density with molecular electrostatic potential (MEP). The energies of frontier molecular orbitals ( E HOMO and E LUMO ), the energy band gap ( E HOMO - E LUMO ), chemical potential ( μ ), chemical hardness ( η ), global electrophilicity index ( ω ) and dipole moments ( D ) were calculated. Crystal structure, Hirshfeld surface, DFT and NBO analyses of two new distorted square-pyramidal mercury complexes are presented.