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Abstract The incorporation of heteroatoms into the framework of polycyclic aromatic hydrocarbons (PAHs), in particular of nitrogen to yield polycyclic aromatic nitrogen heterocycles (PANHs), has been proposed for both astronomical and combustion environments, but no suitable precursors and pathways have been found. Analogous pathways to PAH formation are kinetically or energetically inhibited in the presence of a nitrogen heteroatom. We report on the reaction of phenylnitrene (3PhN,c‐C6H5N) with resonance‐stabilized propargyl radicals (C3H3) and find that the association reaction bifurcates depending on the orientation of the attacking propargyl radical and yields multiple isomeric products. Among them, we identify the condensed‐ring quinoline and conclude that nitrenes are viable candidates to drive the formation of PANHs.
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Probing Effects of Electron Addition to Polycyclic Conjugated Hydrocarbons Containing Four‐Membered Rings
The rectangular cyclobutadiene (CBD, C4H4) is a unique moiety for building nonbenzenoid polycyclic conjugated hydrocarbons with interesting electron‐accepting properties. Herein, the investigation on chemical reduction of several CBD‐containing polycyclic hydrocarbons with increasing conjugation length is reported: biphenylene (C12H8), dimethyl[2]naphthalene (C22H16), and tetramethyl‐dibenzo‐[3]phenylene (C30H22). The two‐step sequential reduction is first demonstrated by in situ spectroscopic investigation and then confirmed by the isolation of single crystals of the reduced products. The X‐ray crystallographic analysis reveals the formation of several mono‐ and doubly reduced products in solvent‐separated and complexed forms. The crystal structures for both neutral parents and corresponding reduced products unravel the changes in bond alternation in each ring of the fused systems. Density functional theory (DFT) and nucleus‐independent chemical shift (NICS) scan calculations reveal that the two‐electron addition reduces the aromatic character in the benzenoid rings but has minor influence on the antiaromatic CBD rings.
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- Award ID(s):
- 2404031
- PAR ID:
- 10590766
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemistryEurope
- Volume:
- 3
- Issue:
- 4
- ISSN:
- 2751-4765
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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