Stable π Radical from a Contracted Doubly N‐Confused Hexaphyrin by Double Palladium Metalation

Abstract

A contracted doubly N-confused dioxohexaphyrin derivative served as a dinucleating metal ligand for unsymmetrical coordination. The complexation of two palladium(II) cations led to the formation of π-radical species that were persistent in atmospheric air in the presence of moisture. Effective delocalization of an unpaired electron over the hexaphyrin backbone could contribute to the distinct chemical stability.

Bis‐Copper(II)/π‐Radical Multi‐Heterospin System with Non‐innocent Doubly N‐Confused Dioxohexaphyrin(1.1.1.1.1.0) Ligand

“…The selective dioxygenation at the α‐positions of confused pyrrole rings in 1‐Cu 2 was confirmed by the spectral analysis of the corresponding free‐base dioxo‐norhexaphyrin 1 , through reductive demetalation with Zn/HCl . The resulting spectroscopic data were identical to those reported previously . The formation of bis‐copper complex 1‐Cu 2 was confirmed by high‐resolution mass and 19 F NMR spectrometry (see Supporting Information).…”

“…The electronic structure of the ground‐state 1‐Cu 2 is likely complicated due to the contribution of various resonance forms (Figure S4). Based on the density functional theory (DFT) calculations, the co‐planar geometry of 1‐Cu 2 was anticipated by the optimized structure obtained by broken‐symmetry (BS) UB3LYP calculation in line with that of bis‐palladium complex 1‐Pd 2 (Figures S5–S6) . The spin density map of the doublet 1‐Cu 2 demonstrated the delocalized nature not only over the whole π‐framework of the dioxo‐norhexaphyrin, but also on both the copper centers (Mulliken spin‐densities: −0.5455 and 0.5652 for Cu 1 and Cu 2 , respectively; Figure a).…”

“…In this work, we have designed and synthesized a novel metal‐radical heterospin compound based on the expanded porphyrin bis‐copper complex ( 1‐Cu 2 ), which is inspired by our previous report on a contracted hexaphyrin bis‐palladium complex ( 1‐Pd 2 ) with a highly stable π‐radical character ( S= 1 / 2 ; Figure ) . A copper(II)‐radical hybrid spin complex has been considered as a simple and significant platform of heterospin system because a square‐planar d 9 Cu II ion has a well‐defined spin orbital of 3d x2−y2 .…”

“…Consistently, significant reductions of the coefficients of the spin densities on the cationic and anionic hexaphyrin ligands were seen (Figure S14). On this basis, the formal aromaticity of the dioxo‐norhexaphyrin moiety in 1‐Cu 2 is considered as a 25 π‐electronic structure as observed in 1‐Pd 2 . The nonaromatic nature of 1‐Cu 2 was evaluated by nuclear‐independent chemical shifts (NICS) value of −3.59 ppm at the global center of the macrocycle.…”

Skeletal Rearrangement of Twisted Thia‐Norhexaphyrin: Multiply Annulated Polypyrrolic Aromatic Macrocycles

“…[4a, 6, 7] Subsequently,t he inner carbon sites play essential roles in the rational functionalization via carbonyl-or ethenyl-bridgings,o ro xidative ring fusions at the cores. [9] Upon modification of the linking modes,wehave developed highly twisted and nonaromatic porphyrinoids (6,F igure 1b)e mbedded with an NÀCl inked confused bipyrrole moiety. [9] Upon modification of the linking modes,wehave developed highly twisted and nonaromatic porphyrinoids (6,F igure 1b)e mbedded with an NÀCl inked confused bipyrrole moiety.…”