Molecular Orbital Theory Applications in Coordination Chemistry

Molecular orbital theory has long underpinned our understanding of how ligands and metal centres interact to form coordination complexes. By constructing delocalised orbitals that span both metal and ligand atoms, researchers can rationalise bond strengths, electronic spectra and reactivity trends. In particular, the concepts of frontier orbitals—highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO)—allow prediction of electron flow during bond formation and activation processes. Applications range from interpreting the geometry and spin states of transition-metal complexes to designing novel catalysts for small-molecule activation. Advances in computational methods now permit routine mapping of metal–ligand bonding, quantification of σ-donation and π-backbonding contributions, and evaluation of reaction pathways on potential energy surfaces. Such insights have driven progress in homogeneous catalysis, materials design and bioinorganic chemistry by revealing how subtle changes in ligand electronic properties influence activity and selectivity. Overall, molecular orbital theory offers a coherent framework for correlating structure with function across a broad spectrum of coordination compounds.

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Molecular Orbital Theory Applications in Coordination Chemistry publication trend

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Technical terms

Molecular orbital (MO): A mathematical function describing an electron’s wave-like behaviour across multiple atoms in a molecule.

HOMO and LUMO: The highest occupied and lowest unoccupied molecular orbitals; key determinants of reactivity and optical properties.

σ-donation: Electron donation from a filled ligand orbital into an empty metal orbital along the internuclear axis.

π-backbonding: Electron donation from a filled metal d-orbital into an empty antibonding orbital on a ligand.

Density functional theory (DFT): A quantum-mechanical method that approximates electron correlation using functionals of the electron density.

Coordination complex: A compound in which a central metal atom or ion is bonded to surrounding molecules or ions (ligands) via coordinate covalent bonds.

References

1. Density functional theory methods applied to homogeneous and heterogeneous catalysis: a short review and a practical user guide. Physical Chemistry Chemical Physics (2024).
2. Unexpected formation of polymeric silver(I) complexes of azine-type ligand via self-assembly of Ag-salts with isatin oxamohydrazide. Royal Society Open Science (2018).
3. The Challenging Reaction of Cyclopropenones with Benzamide Catalyzed by Rh(III): A Computational Study. Organometallics (2024).