Protonation of the Trimethylated Pyrichrominium Ion
نویسنده
چکیده
Spectroscopic manifestations of protonation of the trimethylated pyrichrominium ion studied previously experimentally [1] are investigated using a semiempirical IN DO /S Cl method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with experimental spectra. Calculated charge densities on nitrogen atoms are correlated with experimental pK a values for the ground and lowest excited singlet and triplet states. The possibility of the proton transfer reaction (phototautomerization) in the lowest excited singlet state of monoprotonated species is discussed on the basis of IN DO /S Cl calculations, fluorescence and absorption spectroscopy.
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