Structural isomerism of corroles: Theoretical consideration using DFT model chemistry

Using density functional theory (DFT) with the M06 functional and the def2TZVP basis set, combining D3 version of Grimme’s dispersion, the molecular structures of 10 structural isomers of corrole – [18]corrole(1.1.1.0) (A), [18]corrole(1.1.1.0) (B), [[18]corrole(2.0.1.0) (A), [18]corrole(2.0.1.0) (B), [18]corrole(1.0.0.2) (A), [18]corrole(1.0.0.2) (B), [18]corrole(1.0.0.2) (C), [18]corrole(1.0.0.2) (D), [18]corrole(3.0.0.0) (A), and [18]corrole(3.0.0.0) (B), were calculated. Calculations indicate that the [18]corrole(1.1.1.0)(A) is the most stable isomer, although the difference in total energy values is very small (< 2 kJ/mol), the least stable isomer is [18]corrole(3.0.0.0)(A). whose total energy is almost 200 kJ/mol higher. The standard enthalpy [Formula: see text], entropy [Formula: see text] and Gibbs energy [Formula: see text] of formation of these compounds were also calculated. The values of the most important bond lengths, bond and non-bond angles in these compounds are presented. It was noted that in almost all of these isomers, both the groupings of four nitrogen atoms and the 15-membered macrocycles containing them are non-planar, and in some cases exhibit a very significant deviation from coplanarity. All four interatomic distances between neighboring nitrogen atoms in all these compounds are different; the same applies to the non-valent angles between these atoms. NBO analysis of all the above isomers was carried out. On the basis of its data, a high degree of delocalization of the electron density in these compounds was stated.