An insight into the non-covalent Pb•••S and S•••S interactions in the solid-state structure of a hemidirected lead(II) complex

A heterodinuclear copper(II)/lead(II) complex with a compartmental 'reduced Schiff base' ligand (having inner N2O2 and outer compartments) has been synthesized and characterized. Single-crystal X-ray diffraction analysis confirmed its structure. The X-ray data indicate that the inner N2O2' compartment of the compartmental reduced Schiff base is occupied by copper(II) while the outer compartment is occupied by lead(II). A thiocyanate anion is coordinated to the copper(II) center via its N-end, whereas, another thiocyanate ion is linked to the lead(II) center via its S-end and is semi-coordinated to the copper(II) center through its N-end. A hemidirectionally coordinated lead(II) center is well suited for establishing tetrel bonding interactions. We estimated the BSSE (basis set superposition error) corrected energies of non-covalent S center dot center dot center dot S, Pb center dot center dot center dot pi, and pi center dot center dot center dot pi interactions and N-H hydrogen bonding along with tetrel bonding by DFT calculations. To obtain an insight into the physical nature of these bonds, we extensively used Bader's quantum theory of atoms-in-molecules (QTAIM). Additionally, the non-covalent interaction reduced density gradient (NCI-RDG) method established nicely the presence of such non-covalent intermolecular interactions. Here, we also used natural bond orbital (NBO) analysis to find out the origin of S center dot center dot center dot S and Pb center dot center dot center dot S bonding.