# Electron Donor–Acceptor Chromophore Assembly as an Enabling Process for the Overall Light-Driven Reduction of Phosphine Oxides

## TL;DR

Scientists developed a light-driven method to convert phosphine oxides into useful phosphines without needing added catalysts.

## Contribution

A novel photocatalysis-free method for phosphine synthesis from phosphine oxides using a donor–acceptor complex is introduced.

## Key findings

- Phosphine oxides are converted to phosphonium salts and then reduced to phosphines in 40–80% yields.
- The process uses a self-formed donor–acceptor complex for light absorption and charge separation.
- This method offers a sustainable alternative to traditional thermal methods for phosphorus recycling.

## Abstract

Phosphines make up
one of the largest classes of organophosphorus
compounds, with applications in academic research and industry. Their
preparation from phosphine oxides is mechanistically and thermodynamically
highly challenging but opens the possibility for phosphorus recycling.
We show that phosphine oxides can be converted into their corresponding
phosphonium salts and subsequently reduced in a light-driven reaction
to obtain the desired phosphines in 40–80% overall yields in
a one-pot procedure. The reported methodology is free of exogenously
added photocatalysts and utilizes the in situ formation
of a photoactive donor–acceptor complex for light absorption
and charge separation. Overall, the presented photochemical approach
to reducing phosphonium salts that arise from phosphine oxides represents
a valuable alternative to classical thermochemical methods for phosphorus
recycling.