Copper-dioxygen complexes and their roles in biomimetic oxidation reactions - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 90

protein side-on structure. Subsequently, 6 4 a side-on
superoxocopper(II) complex has been generated and structurally characterized
by the same group; ) has

(resonance Raman).
Certain other tridentate ligands with nitrogen donors were also found
to give copper(I) complexes which bind to give side-on
peroxo dicopper(II) products having intense UV (345-365 nm) charge-transfer
bands like those found in oxy-hemocyanin and oxy-tyrosinase. 9,62,65-77
Detailed electronic structural studies indicate this is characteristic of this
binding mode and is accompanied by the low v(O-O) values
due to Cu(II)-to-peroxo electron donation to the peroxide O-O

( 3

(2,330), O-O = 1.22 (3) Å and

orbital. 78

Based on a low-temperature EXAFS studies, we first 76 proposed this
structure for binuclear complexes containing linked PY2
chelates (PY2 = bis[2-(2-pyridyl)ethyl]amine), i.e., ligands Nn (see diagram).