A Naked FeIII-(O22-)-CuII Species Allows for Structural and Spectroscopic Tuning of Low-Spin Heme-Peroxo-Cu Complexes

Here we describe a new approach for the generation of heme-peroxo-Cu compounds, using a naked complex synthon, [(F8)FeIII-(O-2(2-))-Cu-II(MeTHF)(3)](+) (MeTHF = 2-methyltetrahydrofuran; F-8 = tetrakis(2,6-difluorophenyl)porphyrinate). Addition of varying ligands (L) for Cu allows the generation and spectroscopic characterization of a family of high- and low-spin FeIII-(O-2(2-))Cu--(II)(L) complexes. These possess markedly varying Cu-II coordination geometries, leading to tunable Fe-O, O-O, and Cu-O bond strengths. DFT calculations accompanied by vibrational data correlations give detailed structural insights.