Persistent four-coordinate iron-centered radical stabilized by π-donation

Abstract

Dinuclear iron carbonyl complex 2, which contains an elongated unsupported Fe–Fe bond, was synthesized by the reaction between Fe₂(CO)₉ and phosphinyl radical 1. Thermal Fe–Fe bond homolysis led to the generation of a four-coordinate carbonyl-based iron-centered radical, 3, which is stabilized by π-donation. Complex 3 exhibited high reactivity toward organic radicals to form diamagnetic five-coordinate Fe(II) complexes.