Secondary Coordination Sphere Influence on the Reactivity of Nonheme Iron(II) Complexes: An Experimental and DFT Approach

The new biomimetic ligands N4Py2Ph (1) and N4Py2Ph,amide (2) were synthesized and yield the iron­(II) complexes [FeII(N4Py2Ph)­(NCCH3)]­(BF4)2 (3) and [FeII(N4Py2Ph,amide)]­(BF4)2 (5). Controlled orientation of the Ph substituents in 3 leads to facile triplet spin reactivity for a putative FeIV(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 FeIIIOOR species which decays without arene hydroxylation. These results provide new insights regarding the impact of secondary coordination sphere effects at nonheme iron centers.