spin-orbit coupling

Catalysis of controlled selective oxidation of hydrocarbons utilizing molecular oxygen, being of great potential for the environmental friendly chemical industry, has to be designed by analogy with biological enzymatic reactions. Catalysis of oxidation of hydrocarbons by paramagnetic dioxygen avoiding a classical free radical chain mechanism needs to overcome spin prohibition. Classification of spin catalysis in biological activation of dioxygen is presented in this review and discussed in connection with known industrial processes.

Potential energy curves of the ground and a few excited states of the BrO- and HOBr along the photodissociation reactions, which correlate with lower dissociation limits are obtained on the base of calculations results by ab initio method. The singlet-triplet nonadiabatic transition with dissociation of the ground Х1+ state to lower limit О(3Р) + Br-(1S) is predicted on the basis of calculations results. The ground singlet Х1+ state of the BrO- has predissociative and metastable character for the upper vibrational levels.

Molecular oxygen is a paramagnetic gas with the triplet O2( ) ground state which exhibits just sluggish chemical reactivity in the absence of radical sources. In contrast, the excited metastable singlet oxygen O2( ) is highly reactive; it can oxygenate organic molecules in a wide range of specific reactions which differ from those of the usual triplet oxygen of the air. This makes the singlet oxygen an attractive reagent for new synthesis and even for medical treatments in photodynamic therapy.