Strong Stacking Between Organic and Organometallic Molecules as the Key for Material Design

Abstract

Very attractive properties of organic-inorganic materials consisting of planar molecules, namely magnetism, conductivity. non-linear optics and catalysis. are highly dependent on the stacking interactions. Metal-chelate rings and aromatic molecules are very common constituents of these materials. The search of Cambridge Structural Database has shown that stacking interactions of chelates and aromatic molecules occur very often in crystal structures: these interactions are of very similar geometries to stacking between two aromatic molecules. The energies of these interactions have been calculated at high theoretical levels, showing much stronger stacking of six-membered chelate with benzene that stacking of two benzene molecules. The stacking interaction between two benzene molecules is -2.73 kcal/mol. while the interaction between benzene and chelate ring dependent on the metal type. being stronger for coopper(II)-chelate (-6.08 kcal/mol) than for nickel(II)-chelate (-4.68 kcal/mol). The energies of interactions are calculated at CCSD(T)/CBS level and the benchmark study was performed to find Minnesota functionals that can reproduce this data.