STUDY OF STRUCTURAL FACTORS DETERMINATIVE FOR BASICITY OF THE ALKYLATED DERIVATIVES OF THE FREE BASE CORROLES
Equilibrium molecular conformation of the long wavelength NH tautomer for the family of alkylated derivatives of the free base corrole has been determined by using quantum-chemical methods. It was found that dihedral angle φ<sub>D</sub> between the pyrrolenine ring undergoing protonation and macrocycle mean plane correlates with the С<sub>1</sub>С<sub>19</sub> bond length in the dipyrrole fragment. С<sub>1</sub>С<sub>19</sub> bond length depends on the architecture of peripheral substitution which determines the strength and localization of the steric hindrances on the macrocycle periphery. When there are no substituents in the С<sub>2</sub> and С<sub>18</sub> positions of the pyrrole rings belonging to the dipyrrole fragment, the С<sub>1</sub>С<sub>19</sub> bond length would be of minimum, and the tilting angle φ<sub>D</sub> reaches the maximum value. Basicity of such derivatives is the highest. On the contrary, introduction of substituents into dipyrrole fragment leads to increase in the С<sub>1</sub>С<sub>19</sub> bond length and decrease in tilting angle φ<sub>D</sub>. As a result the macrocycle basicity decreases. The molecular structures with given basicity can be proposed based on the established structure - property relationship.