A 3D metal hydrogen-bonded organic framework based on a trans-dichloropalladium complex with bis(N-heterocyclic carbene) ligands

Abstract

In this study, a trans-PdCl2(NHC)2 complex, where NHC is 1-(4-fluorobenzyl)-3-vinyl-1,3-dihydro-2H-imidazolin-2-ylidene, was synthesized with a 60 % of yield. Crystallographic analysis revealed a significant intermolecular non-classical hydrogen bonding interaction of the type CH···Cl between an aryl proton adjacent to the electronegative F atom and a Cl ligand on the palladium carbene center. Additionally, a slightly longer CH···Cl interaction was identified through normalized contact distance calculation in Hirshfeld surface analysis. These interactions acted as connectors, linking the metal complex nodes to form a 3D 6-connected metal hydrogen-bonded organic framework (M−HOF). The stabilizing energy of 1.02 kcal/mol for the major CH···Cl interaction was confirmed through natural bond orbital (NBO) analysis. Hirshfeld surface analysis further revealed other intermolecular interactions, including the significance of CH···F and CH···π contacts in stabilizing the crystal packing. This work presents a rare example of a 3D M−HOF based on a palladium NHC complex and highlights the potential of utilizing FCC—H···Cl—Pd supramolecular synthons to assemble multi-dimensional M−HOFs.