Inspecting the nonbonding and antibonding orbitals in a surface-supported metal-organic framework.

By using low-temperature scanning tunnelling microscopy and spectroscopy, ligand field theory and density functional theory calculations, we revealed the spatial distribution and energy separation of the nonbonding and antibonding orbitals associated with the top-Ni atoms in a surface-supported Ni-TPyP metal-organic framework with dinuclear coordination centres.