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Short-lived intermediates in photochemistry of an OsCl62- complex in aqueous solutions
Two mechanisms of (OsCl62-)-Cl-IV photolysis were studied by means of quantum chemical calculations in gas and aqueous phases. The difference between these mechanisms is in the nature of the possible Os(IV) key intermediates (KI). According to calculations, the intermediate is an (OsCl5-)-Cl-IV complex of square pyramidal coordination geometry. The calculations do not give an opportunity to make an unambiguous choice between the triplet and quintet multiplicities of (OsCl5-)-Cl-IV. The calculated CASSCF/IMCP-SR1 transition energies for 5Os(IV)Cl(5)(-) are lower than for 3Os(IV)Cl(5)(-), while the calculated XMC-QDPT2/SBKJC spectra for the triplet state are in better agreement with the experimental absorption spectrum of the KI than for the quintet state.