Dioxygen complexes electronic spectra

A number of investigations of the copper-group oxides and dioxygen complexes have been reported. The electronic spectra of CuO, AgO, and AuO were recorded in rare-gas matrices (9), and it was found that the three oxides could be formed effectively by cocondensation of the metal atoms with a dilute, oxygen matrix, followed by near-ultraviolet excitation. The effective wavelengths for CuO or AgO formation were X > 300 nm and for AuO was X > 200 nm. In addition, the laser fluorescence spectrum of CuO in solid Ar has been recorded (97). 

The singlet (S = 0) state lies about 1000 cm above the ground state triplet (S = 1) in the EPR spectrum of free dioxygen. Transitions associated with triplet oxygen in solution are detectable by EPR at low temperatures, but dioxygen complexes with even electron metal centers (e.g., ferroheme) are not generally observable by this method. Usually, only odd electron systems (Kramers systems) are detectable by magnetic resonance. 

Picket-fence porphyrin (TpivPP)-iron-V-methylimidazole-02 complex is used as an artificial P-450, and the decomposition rates are investigated in details in the presence of HCl and H2-colloidal platinum supported on poly(vinylpyrrolidone) with or without addition of benzoic anhydride. From the decay rates of the oxy complex followed by electronic spectrum under a variety of conditions, pseudo-first-order rate (with the complex) constants are obtained. ( Kinetics and Mechanism of Reductive Dioxygen Activation Catalyzed by P-450 Model System. Iron Picket... 

Hyla-Krispin, Natakaniec and Jezowska-Trzebiatowska have carried out EHMO type calculations on the ions [(H3N)5Co02Co(NH3)s] and [(NC)5Co02Co(CN)5] The 3 Og and orbitals of dioxygen lie well below the metal d-orbitals, the in-plane orbital just below the t2g metal d-orbitals and the Jr (l) orbitals (the HOMO) between the t2g and eg metal d-orbitals. In agreement with the EPR spectrum the unpaired electron in the superoxo complex is localised on dioxygen. 

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