Triphenylantimony(V) Catecholates of the Type (3-RS-4,6-DBCat)SbPh₃-Catechol Thioether Derivatives: Structure, Electrochemical Properties, and Antiradical Activity

• Main Authors: Ivan V. Smolyaninov, Georgy K. Fukin, Nadezhda T. Berberova, Andrey I. Poddel’sky
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Molecules
• Subjects: redox-active ligand; catechol; antimony; X-ray; cyclic voltammetry; antiradical activity
• Online Access: https://www.mdpi.com/1420-3049/26/8/2171

A new series of triphenylantimony(V) 3-alkylthio/arylthio-substituted 4,6-di-tert-butylcatecholates of the type (3-RS-4,6-DBCat)SbPh₃, where R = n-butyl (<b>1</b>), n-hexyl (<b>2</b>), n-octyl (<b>3</b>), cyclopentyl (<b>4</b>), cyclohexyl (<b>5</b>), benzyl (<b>6</b>), phenyl (<b>7</b>), and naphthyl-2 (<b>8</b>), were synthesized from the corresponding catechol thioethers and Ph₃SbBr₂ in the presence of a base. The crystal structures of <b>1</b>, <b>2</b>, <b>3</b>, and <b>5</b> were determined by single-crystal X-ray analysis. The coordination polyhedron of <b>1</b>–<b>3</b> is better described as a tetragonal pyramid with a different degree of distortion, while that for <b>5</b>- was a distorted trigonal bipyramid (<i>τ</i> = 0.014, 0.177, 0.26, 0.56, respectively). Complexes demonstrated different crystal packing of molecules. The electrochemical oxidation of the complexes involved the catecholate group as well as the thioether linker. The introduction of a thioether fragment into the aromatic ring of catechol ligand led to a shift in the potential of the “catechol/o-semiquinone” redox transition to the anodic region, which indicated the electron-withdrawing nature of the RS group. The radical scavenging activity of the complexes was determined in the reaction with DPPH radical.