Synthesis, structural characterization, crystal structure and theoretical study of a Pd(II)-salen complex with propylene linkage

In order to explore the insights into the structural bonding of the studied complex, computational measurements has been carried out. Combined topology and NBO studies were made to explore the nature of PdO and PdN bonding in the complex. The natural charges showed that the transfers of the negative charge from the ligand to palladium atom is at 1.4157-1.4312 e. Atom in a molecule (AIM) analysis showed the electron density (ρ(r) > 0.1) and its Laplacian (∇2ρ(r) > 0). These topological parameters showed that covalent bonding interactions are dominant in PdN and PdO bonds. However, PdN bonds have more covalent characters than PdO bonds, which is further confirmed by the ratio of local electron potential energy density to the local electron kinetic energy density (|V(r)|/G(r)) found to be higher for PdN bonds (1.1683-1.1993) as compared to PdO bonds (1.0689-1.0926). AIM and NBO reveal that shorter PdN and PdO bonds have higher interaction energies (Eint) and hence higher bond covalence.