A model electronic Hamiltonian for the self-assembly of an octahedron-shaped coordination capsule

A model electronic Hamiltonian to describe ligand exchange reactions of palladium(ii) complexes with pyridine (Py) and tridentate (L) ligands was developed. It was shown that the model Hamiltonian can adequately reproduce the structures and potential energies of the reactant/product, intermediate, and transition state of the ligand exchange reaction of [PdPy₄]²⁺ with free Py. The model Hamiltonian was extended to describe reactions of multi-metal complexes and was adequately applied to describe various clusters, [Pd_aL_bPy_c]^2a+, in the self-assembly of an octahedron-shaped coordination capsule, [Pd₆L₈]¹²⁺. The heterogeneity in the energetics of intermediate species [Pd_aL_bPy_c]^2a+ was strongly suggested by the calculations, and the underlying microscopic interactions were clarified with the geometrical motif. The present framework provides a way to examine the reaction mechanisms of complex metal ligand self-assembly, which can be complementary microscopic information to the recently investigated novel experimental results for the real time evolutions.