Copper intermediate valence state

RsMigPn- Data for R5M19P12 compounds are given in table 81. A plot of the unit-cell volumes (fig. 92) suggests an intermediate-valence state of cerium atoms in these compounds. For copper compounds no physical property investigations were carried out. 

The mixed valency situation may be equally well described in terms of bands. The band to be considered in the case of bismuth is the Bi6s-02p band. The band in the case of copper is the Cu3d y2 -02p band. Both of these are d bands. For the lowest oxidation state (Cu1 or Bira), these bands are filled for the highest oxidation state (Cu111 or Biv), these bands are empty. According to simple band structure considerations, we would expect metallic properties for any partial filling of these o bands in bismuth and copper oxides. While metallic properties are indeed observed for most of the intermediate... 

Tentative structures of intermediate states observed when starting the reaction from fully reduced or mixed-valence enzyme. The rectangle denotes the heme 03-copper B site, where Y is tyrosine-244 covalently bonded to the copper ligand H240 (Figure 3h). The formal redox states of heme a and the Cua center are shown on the left side of the rectangle... 

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