قدرت محمودی

Two new Pb(II) complexes of nicotinoylhydrazone and piconoylhydrazone-based ligands and three different anionic coligands (acetate and iodide) have been synthesized and characterized by structural, analytical and spectroscopic methods. The ligands coordinate to the Pb(II) metal center in a tridentate fashion via two nitrogen and one oxygen donor atoms either in mono-deprotonated or in neutral forms. Single-crystal X-ray crystallography reveals that the molecular complexes aggregate into larger entities depending upon the anion coordinated to the metal centre. The Pb(II) center is hemidirectionally coordinated and, consequently, it is sterically ideal for establishing tetrel bonding interactions. Consequently, in the crystal structures of all complexes, the Pb participates in short contacts with nitrogen or iodide atoms. These contacts are shorter than the sums of the van der Waals radii and larger than the sums of the covalent radii; therefore it can be defined as noncovalent tetrel bonding interactions. They interconnect the covalently bonded units (monomers or dimers) into supramolecular assemblies (1D infinite chains and 3D structures). Hirshfeld surface analysis and fingerprint plots have been used to analyse the contribution of contacts involving Pb atom. We have analysed the interesting supramolecular assemblies observed in the solid state of all four complexes by means of DFT calculations and characterized using the Bader’s theory of atoms-in-molecules.