Abstract
The distribution of the electrostatic potential of the molecule of porphine (P) and the anions formed by the successive elimination of one and two central protons from it has been studied by the SCF-MO-LCAO method in the all-valence-electron CNDO/2 approximation. The electrostatic potential of the potential of the (P-2HO2− dianion is characterized by the presence of four minima located at a distance of about 1 Å from the nitrogen atoms. The potential in them is equal to −991 kJ/mole. The value of the potential at the center of the opening is −978 kJ/mole. The distribution of the electrostatic potential of the (P-H)− anion with a fixed position of the proton near one of the nitrogen atoms is characterized by the presence of a deep valley situated at the oppositely lying nitrogen atom perpendicularly to the N-H bond. The potential of the molecule of P in the plane of the ring does not have negative values, attesting to the energetic unfavorability of the planar conformations of the (P+H)+ cation.
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Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 2, pp. 216–220, March–April, 1986.
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Zayats, V.Y., Pinchuk, V.M. & Lobanov, V.V. Motion of protons in the central opening of porphyrins. Theor Exp Chem 22, 201–204 (1986). https://doi.org/10.1007/BF00519194
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DOI: https://doi.org/10.1007/BF00519194