DENSITY FUNCTIONAL STUDY OF HYDRATED LA(III) IONS IN ACETONITRILE
Rubrics: 1. CHEMISTRY
Authors:
1.
KNITU; KNRTU
2.
Kazan National Research Technological University
Russian Federation
Russian Federation
Type:
Article
Pages:
from 23
to 26
Status:
Published
Received:
05.08.2025
Accepted:
07.08.2025
Published:
07.08.2025
Language:
Russian
Keywords:
DENSITY FUNCTIONAL THEORY, SOLVATION, LA(III) COMPLEXES
Abstract (English):
In this work, a quantum chemical study was carried out within the framework of the density functional theory at the GGA level of the PBE functional using the valence-split triple ζ atomic basis set of the second generation def2-TZVP of Alrich and coworkers taking into account the solvation effects in the polarized continuum C-PCM model. The theoretical study is based on a real experiment, the methodology of which assumes that an aqueous solution of lanthanum(III) nitrate or chloride is injected into the reaction mixture in which the solvent is acetonitrile. For this reason, the question arises in what form exactly the lanthanum(III) ions will exist in this reaction mixture. In the work, a sequential substitution of water molecules by acetonitrile molecules in the inner coordination sphere of lanthanum(III) was carried out considering all the intermediate forms of mixed complexes. It was shown that in acetonitrile solution, lanthanum(III) aqua complexes are more stable compared to acetonitrile complexes. Since the deprotonating agent triethylamine is usually present in the reaction mixture in the experiment, the probability of deprotonation of the aqua complex under the action of triethylamine with the splitting off of one and two protons was additionally considered. As a result, it was established that the most probable particle under these conditions should be considered the complex [La(H2O)8OH]2+. It is this particle that should be considered further as the initial complex when studying the reaction of La(III) complexation with organic ligands in acetonitrile. This result is important, since it allows for a more correct assessment of the energetics of complex formation in the reaction mixture.
In this work, a quantum chemical study was carried out within the framework of the density functional theory at the GGA level of the PBE functional using the valence-split triple ζ atomic basis set of the second generation def2-TZVP of Alrich and coworkers taking into account the solvation effects in the polarized continuum C-PCM model. The theoretical study is based on a real experiment, the methodology of which assumes that an aqueous solution of lanthanum(III) nitrate or chloride is injected into the reaction mixture in which the solvent is acetonitrile. For this reason, the question arises in what form exactly the lanthanum(III) ions will exist in this reaction mixture. In the work, a sequential substitution of water molecules by acetonitrile molecules in the inner coordination sphere of lanthanum(III) was carried out considering all the intermediate forms of mixed complexes. It was shown that in acetonitrile solution, lanthanum(III) aqua complexes are more stable compared to acetonitrile complexes. Since the deprotonating agent triethylamine is usually present in the reaction mixture in the experiment, the probability of deprotonation of the aqua complex under the action of triethylamine with the splitting off of one and two protons was additionally considered. As a result, it was established that the most probable particle under these conditions should be considered the complex [La(H2O)8OH]2+. It is this particle that should be considered further as the initial complex when studying the reaction of La(III) complexation with organic ligands in acetonitrile. This result is important, since it allows for a more correct assessment of the energetics of complex formation in the reaction mixture.
Keywords:
DENSITY FUNCTIONAL THEORY, SOLVATION, LA(III) COMPLEXES
DENSITY FUNCTIONAL THEORY, SOLVATION, LA(III) COMPLEXES
