Uranyl Complexes with Hydroxybenzoates: Stability, Structure, and Effects of Hydroxyl Groups Quantity and Position

This paper reports stability constants for complexes formed between uranyl ions and benzoate, as well as 12 anions of various hydroxybenzoates, determined at T = 298.2 K, p = 0.1 MPa, and ionic strength I = 0.05 M (NaClO 4 ). The relationship between the protolytic properties of the corresponding acids and complex stability is established through analysis of both our experimental data and literature values. A simple incremental approach quantifies the contribution of hydroxyl groups in ortho-, meta-, and para-positions to the stability constants. 13 C NMR spectroscopy was employed to identify the functional groups of hydroxybenzoates participating in complexation. Additionally, the crystal structure of [UO 2 (2,6-DHBA) 2 (H 2 O) 2 ]·1.5H 2 O was refined using X-ray diffraction analysis.