Frontiers in Chemistry and Chemical Engineering
The ability of the bismuth (Bi) to maneuver between different oxidation states in a catalytic redox cycle will be presented. We will show how Bi challenges the current dogmas of catalysis by emulating canonical organometallic steps of transition metals. A series of Bi complexes capable of revolving between oxidation states Bi(I)/Bi(III) and Bi(III)/Bi(V) have been unlocked and applied in various contexts of catalysis for organic synthesis. For example, capitalizing on the Bi(III)/Bi(V) redox pair, we have developed a catalytic protocol for the C‒F, C‒O and C‒N bond formation. We will show how bismuth is capable of a unique 5-membered reductive elimination step, which differs from the traditional 3-membered of transition metals.
Additionally, we will show how a low-valent redox manifold based on Bi(I)/Bi(III) has been applied in the reduction of hydrazines and nitro compounds, the decomposition of inert N2O and SF6 and the catalytic hydrodefluorination of C(sp2)‒F bonds. In addition, we will show how one-electron pathways are also accessible, thus providing a platform for SET processes capitalizing on the triad Bi(I)/Bi(II)/Bi(III) for organic synthesis.
Finally, we will also show how we relativity can be used to infer unknown chemical and physical properties to bismuth. For example, we will show how the intimiate relationship between relativity and red-light permit Bi(I) compounds to unlock unusual oxidative addition reactions to aryl halides. Also, we will show how we synthesized the first mono-coordinated bismuthinidne, which represents the first isolated main group diradical. Again here, the large contribution of the SOC derived from relativity results in an unusual diamagnetism for a triplet ground state.
For all methodologies, a combination of rational ligand design with an in depth analysis of all the elementary steps proved crucial to unlock the catalytic properties of such an intriguing element of the periodic table.