Proceedings of The XXVIII Annual International Conference "Saratov Fall Meeting 2024", September 23-27, 2024
Spectroscopy of condensed matter

The influence of the structure of tetradentate phosphonates on the stability constants of their complexes with $f$-elements (La, Nd, Eu, Lu, and Th)

Ts. B. Sumyanova, A. A. Kirsanova, N. E. Borisova

Lomonosov Moscow State University

Abstract: The influence of the central metal ion on the stability constants of complexes of thorium, lanthanum, neodymium, europium, and lutetium with phosphonate ligands based on 2,2'-bipyridine and 1,10'-phenanthroline has been studied. Solutions in acetonitrile were investigated using spectrophotometric titration at a constant temperature of 25 $\pm$ 0.1$^\circ$C. Absorption spectra were obtained for the studied phosphonate ligands and their complexes. The metal-to-ligand ratios in the formed complexes were determined using spectrophotometric titration curves and the method of isomolar series. Factor analysis was used to determine the number of independent absorbing components in the chemical system. The stability constants of lanthanide and thorium complexes with phosphonate ligands were calculated using the HypSpec2014 program. Dependence curves of the complex stability constants on the ionic radii of the metals were plotted.

Keywords: complex stability constant, $f$-elements, lanthanides, thorium.

Received: 10.12.2024
Revised: 20.01.2025
Accepted: 07.04.2025

DOI: 10.61011/OS.2025.05.60780.21-25

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