قدرت محمودی

Apart from the widely used hydrogen bonding interactions for the construction/modification of MOFS, other specific noncovalent interactions like σ–hole interactions, especially halogen bonds, are becoming prominent players [1-3].The strongest σ–hole interactions occur in systems where a heavy atom of groups IV to VII is covalently bonded to electronegative ones [4]. Taking advantage of this understanding, herein we report the synthesis and X-ray characterization of four new Pb(II) complexes with (iso)nicotinohydrazide-based ligands and different anions (azide, nitrate, acetate and iodine) as coligands. The nature of the tetrel bonds in all four structures was studied by DFT calculations, which showed the presence of the σ–hole at the Pb atom and the considerable strength of these interactions. In these MOFs, Pb⋯S and Pb⋯N noncovalent tetrel bonds interconnect the covalently bonded units into supramolecular assemblies. A combined DFT study and a statistical survey of the Cambridge Structural Database (CSD) revealed that tetrel bonds with hemidirectionally coordinated lead occur with high probability and with predictable geometries, thus playing an important role in the solid-state chemistry of lead.