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

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-iPr2 C6 H3 ) 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.