Secondary coordination sphere influence on the reactivity of nonheme iron(II) complexes: an experimental and DFT approach.

The new biomimetic ligands N4Py(2Ph) (1) and N4Py(2Ph,amide) (2) were synthesized and yield the iron(II) complexes Fe(II)(N4Py(2Ph))(NCCH3)2 (3) and Fe(II)(N4Py(2Ph,amide))2 (5). Controlled orientation of the Ph substituents in 3 leads to facile triplet spin reactivity for a putative Fe(IV)(O) intermediate, resulting in rapid arene hydroxylation. Addition of a peripheral amide substituent within hydrogen-bond distance of the iron first coordination sphere leads to stabilization of a high-spin Fe(III)OOR species which decays without arene hydroxylation. These results provide new insights regarding the impact of secondary coordination sphere effects at nonheme iron centers.