Bismuth goes "radical" to mimic the behavior of transition metals

Mülheim scientists make great progress in the use of bismuth in catalysis

Scientists from Mülheim have found a new reactivity mode for bismuth compounds. They published their results with “Nature Chemistry”. 

So-called “cross-coupling reactions" are one of the most important modern tools for making new bonds in synthetic organic chemistry. They are used as key step in the preparation of drugs. Traditionally, these cross-couplings have been conducted mainly with expensive or toxic transition metals as catalysts, such as palladium or nickel.

However, scientists at the Max Planck Institut für Kohlenforschung have now succeeded in mimicking the behavior of transition metals with a significantly cheaper element: bismuth. They have discovered the potential of this element to easily forge carbon-nitrogen bonds, one of the most used reactions in synthetic medicinal chemistry. The group has now published their results in the journal Nature Chemistry: “Bismuth radical catalysis in the activation and coupling of redox-active electrophiles”

This application is based on the discovery of a fundamentally new reactivity mode for bismuth compounds: a radical oxidative-addition reaction. In contrast to classical polar reactivity, radical reactions occur by transferring the electrons one-at-a-time. This makes the use of reagents possible that cannot be activated by classical two-electron mechanisms. The use of main-group elements for this type of processes had been hardly researched. However, the Mülheim researchers have now shown that a certain type of bismuth compound shows this radical behavior.

"For a long time, no one was really interested in the catalytic properties of bismuth," explains Mauro Mato, a chemist from Spain. He works as postdoctoral researcher in Josep Cornellà's group and is the first author of the Nature Chemistry paper. This work shows how the discovery of a fundamentally new reactivity mode for bismuth, he says, can enable the development of new reactions with potential applications in the chemical industry, for example, in the synthesis of active ingredients for drugs.