Synthesis of a phenazine radical anion complex: structural and spectroscopic analysis of spin delocalization

What is it about?

In this work, we demonstrate the utility of the phenazine radical anion as a ligand for a metal complex. The ditopicity of the ligand allows it to successfully bind to two different zinc atoms with a radical sitting between them–or so we thought. The electron paramagnetic resonance spectrum instead indicates that the unpaired electron is partially located on the phenazine bridging the two zinc ions and partially located on a phenazine coordinating a sequestered potassium atom in the structure.

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Photo by Ayush Kumar on Unsplash

Photo by Ayush Kumar on Unsplash

Why is it important?

Electron self-exchange is when two versions of the same molecule pass an electron back and forth. Investigating electron self-exchange in radical scaffolds is important for understanding many biological processes, particularly the role of quinones in biological energy conversion. Understanding these processes is also essential for designing high-performance, radical-based electronic materials, such as metal-ion batteries, redox-flow batteries, and molecular magnets. This work gives us a crystallographic and spectroscopic snapshot of this phenomenon.