The Charge Transfer Approach to Heavier Main‐Group Element Radicals in Transition‐Metal Complexes

Abstract

The CoII and FeII complexes 1Co and 1Fe with a coordinated phosphorus radical were easily obtained through a charge‐transfer approach from the MI precursors LMI(tol) (M=Co, Fe; L=CH(MeC=NDipp)2, Dipp=2,6‐iPr2C6H3) to the diazafluorenylidene‐substituted phosphaalkene 1. Structural, magnetic, and computational studies on 1Co and 1Fe indicate a weak antiferromagnetic interaction between the high‐spin MII ion and the phosphorus radical, resulting in a triplet and quartet ground state, respectively. Complexes 1Co and 1Fe are the first examples of phosphorus‐radical‐coordinated transition‐metal complexes synthesized by charge transfer, providing a new approach to access radicals of heavier main‐group elements.