Fluorine Encapsulation and Stabilization of Biologically Relevant Low-Valence Copper-Oxo Cores

Slow crystallization of the dinuclear [(CuTpCF3,CH3)2O2] yields a solid-state solution of the peroxo and bis(hydroxo) complex, but not sterically compressed Cu(III) complexes. Since the CF3 substituents, while encapsulating the peroxo group (see Figure), exhibit unexpectedly low bulkiness, the metal tendency toward low-valency is attributed to fluorine electronic effects. Space-filing view of [(CuTpCF3,CH3)2O2] showing the green region of fluorine steric hindrance of the metal−peroxo core. The two-fold rotationally disordered CF3 groups are shown in full.