In Search of Covalency Measure of Gd(III)-Ligand Interactions

Area of Science:

• Inorganic Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Understanding the chemical bonding in f-element complexes is crucial for applications in separation science and materials development.
• Gadolinium(III) complexes are of interest due to their unique magnetic and luminescent properties.

Purpose of the Study:

• To investigate the nature of chemical interactions between Gadolinium(III) and its ligands (O, F, N) using experimental and theoretical methods.
• To correlate topological parameters with spectroscopic properties and bonding characteristics of Gadolinium(III) compounds.

Main Methods:

• Experimental determination of electron density distribution.
• Density Functional Theory (DFT) calculations for topological and energy parameters.
• Analysis of f-f transition properties and Judd-Ofelt parameters for 18 Gd(III) compounds.

Main Results:

• The covalency of Gd-L bonds is primarily due to charge transfer to Gd(III) 5d orbitals, with lesser transfer to 6s and 4f orbitals.
• Ligand charge donation to Gd(III) increases with lower coordination numbers.
• A correlation was established between the sum of Gd(III)-L bond energies and the energy of Gd(III) 8S7/2 → 2LJ transitions.

Conclusions:

• Increased covalency in Gd(III)-ligand bonds is associated with decreased bond energy.
• Subtle variations in covalent bonding can influence the selectivity of lanthanide and actinide partitioning.
• The study provides fundamental insights into the chemical bonding of f-elements.