Abstract
Electronic structures of pyridine, pyrazine, pyrimidine and pyridazine are studied by a semiempirical SCF method for valence electron systems previously proposed by the present authors. The charge distributions, transition energies and oscillator strengths of these compounds are calculated. The calculated results show fairly good agreement with the observed ones. Using these results, we have further calculated the oscillator strengths of singlet-triplet transitions \((f_{T_1 \to S_0 } )\) and the life times of the triplet states (τ). In this treatment, we have considered the mixing of various singlets with T 1 and triplets with S 0, and the effect of σ-electrons is studied.
Zusammenfassung
Es werden nach einer von den Autoren dieser Arbeit vorgeschlagenen Methode die Elektronenstrukturen von Pyridin, Pyrazin, Pyrimidin und Pyridazin studiert. Die halbempirische SCF-Methode für Valenzelektronensysteme gestattet die Berechnung der Ladungsverteilungen, Übergangsenergien und Oszillatorstärken, die in recht guter Übereinstimmung mit der Beobachtung stehen. Ferner werden die Oszillatorstärken von Singulett-Triplett-Übergängen \((f_{T_1 \to S_0 } )\) und die Lebensdauer von Triplett-Zuständen (τ) berechnet.
Résumé
Les structures électroniques de la pyridine, de la pyrazine, de la pyrimidine et de la pyridazine sont étudiées par une méthode SCF semiempirique pour les électrons de valence proposée précédemment par les auteurs. Les distributions de charge, les énergies de transition et les forces oscillatrices de ces composés sont calculées, donnant des résultats en bon accord avec l'expérience. De plus nous avons calculé les forces oscillatrices des transitions singulet-triplet \((f_{T_1 \to S_0 } )\) et les durées de vie des états triplets (τ). Dans ce calcul nous avons inclus l'interaction de configuration et l'étude de l'effet des électrons σ.
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Yonezawa, T., Katô, H. & Kato, H. Semi-empirical molecular orbital calculations the electronic structure and the spin-orbit coupling in azabenzenes. Theoret. Chim. Acta 13, 125–138 (1969). https://doi.org/10.1007/BF00533436
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DOI: https://doi.org/10.1007/BF00533436