The Linear Electric Field Effect in Stellacyanin, Azurin and in Some Simple Model Compounds

Abstract

All mononuclear Cu(II) sites in frozen solution are non‐centrosymmetric and, unless physically constrained, will have a tetrahedral distortion away from the usual square planar structure often presented for Cu(II) complexes. Blue copper sites such as are found in azurin and stellacyanin have a greater distortion towards a tetrahedral geometry than do simple Cu(II) complexes. The distortion is comparable to that which is observed for Cu(II)‐o‐phenanthroline dichloride, a known tetrahedral complex. Blue copper sites posses as axis of asymmetry directed away from g¶ which could arise from a metal‐sulfur interaction.