Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties

The behavior of the redox-active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)(3)] and [Bi(ATI)(2)L-n][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable-temperature) NMR spectroscopy, line-shape analysis, and single-crystal X-ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann-Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand- and metal-centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored.

Automated summary

The study investigates the behavior of the redox-active aminotroponiminate (ATI) ligand in neutral and cationic bismuth compounds. The results show that switching between ligand- and metal-centered redox events is possible by altering the charge of the compounds. This adds important facets to the rich redox chemistry of ATIs and bismuth compounds.