Stacked-ring aromaticity from the viewpoint of the effective number of π-electrons.

ABSTRACT: In this study, we theoretically examined the mechanism of aromaticity induced in closely stacked cofacial π-dimers of 4nπ antiaromatic molecules, which is called stacked-ring aromaticity, in terms of the effective number of π-electrons (N _π) and Baird's rule. High-precision quantum chemical calculations combined with a multi-configurational wavefunction analysis revealed that double-triplet [¹(T₁T₁)] and intermolecular charge-transfer (CT) electron configurations mix substantially in the ground state wavefunctions of cyclobutadiene and Ni(ii) norcorrole dimer models at small stacking distance (d). Since the T₁ configuration gives rise to two unpaired electrons, the remaining 4n - 2 π electrons still particip

SUBMITTER: Sugimori R 

PROVIDER: S-EPMC11694183 | biostudies-literature | 2025 Jan

REPOSITORIES: biostudies-literature