10.1021/ic7016616.s002 Ivelina Georgieva Ivelina Georgieva Natasha Trendafilova Natasha Trendafilova Adélia J. A. Aquino Adélia J. A. Aquino Hans Lischka Hans Lischka Theoretical Study of Metal−Ligand Interaction in Sm(III), Eu(III), and Tb(III) Complexes of Coumarin-3-Carboxylic Acid in the Gas Phase and Solution American Chemical Society 2007 energy partitioning analysis continuum solvation model Gas Phase SolutionThe interaction carboxylate moiety interaction term population analyses interaction terms ligand deformation energies deprotonated form Solvent effects binding energies covalent contributions water clusters CCSD covalent contribution Theoretical Study DFT reference MP 2 Ln energy decomposition calculations electron distribution analysis 2007-12-10 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Theoretical_Study_of_Metal_Ligand_Interaction_in_Sm_III_Eu_III_and_Tb_III_Complexes_of_Coumarin_3_Carboxylic_Acid_in_the_Gas_Phase_and_Solution/2969830 The interaction of lanthanide(III) cations (Ln(III) = Sm(III), Eu(III), and Tb(III)) with the deprotonated form of the coumarin-3-carboxylic acid (<i>cca</i><i><sup>-</sup></i><sup></sup>) has been investigated by density functional theory (DFT/B3LYP) and confirmed by reference MP2 and CCSD(T) computations. Solvent effects on the geometries and stabilities of the Ln(III) complexes were computed using a combination of water clusters and a continuum solvation model. The following two series of systems were considered:  (i) Ln(<i>cca</i>)<sup>2+</sup>, Ln(<i>cca</i>)<sub>2</sub><sup>+</sup>, Ln(<i>cca</i>)<sub>3</sub> and (ii) Ln(<i>cca</i>)(H<sub>2</sub>O)<sub>2</sub>Cl<sub>2</sub>, Ln(<i>cca</i>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>Cl, Ln(<i>cca</i>)<sub>3</sub>. The strength and character of the Ln(III)−<i>cca</i><i><sup>-</sup></i><sup></sup> bidentate bonding were characterized by calculated Ln−O bond lengths, binding energies, ligand deformation energies, energy partitioning analysis, σ-donation contributions, and natural population analyses. The energy decomposition calculations predicted predominant electrostatic interaction terms to the Ln−<i>cca</i> bonding (ionic character) and showed variations of the orbital interaction term (covalent contributions) for the Ln−<i>cca</i> complexes studied. Electron distribution analysis suggested that the covalent contribution comes mainly from the interaction with the carboxylate moiety of <i>cca</i><sup>-</sup>.