Carbon nanohoop, a class of constrained molecular architecture consisting of linked arene units, has attracted considerable interest from both experimental and theoretical chemists due to their synthetic challenge and aesthetic architectures. Another fascinating and synthetically challenging species, the Möbius-type molecule, has been attracting the scientific community with its elegant structure and aromaticity. Thus, combining two things together, synthesizing a carbon nanohoop with Möbius topology remains more challenging to date.
Disilene has attracted considerable interests due to the trans-bending geometry which is significantly different from the planar alkene. However, the equilibrium between disilene and isomeric silylsilylene has not been fully understood. Here, we report a density functional theory (DFT) study on this equilibrium. Calculations reveal significant effects of substituent, aromaticity and base. Specifically, the parent disilene is thermodynamically more stable than the isomeric silylene.
While sp2-hybridized carbon atoms in hydrocarbons typically contribute only one electron to their aromaticity, metals have more electrons from d or f orbitals available for participating in conjugation in organometallics, complicating the electron counting as well as analysis of their aromaticity. Here, the author comments on the challenges towards understanding aromaticity in organometallics and outlines several remaining questions that have yet to be answered.
The isolated‐pentagon rule (IPR) is a determining structural feature accounting for hollow fullerene stabilization and properties related to Cn (n ≥ 60) cages. The recent characterization of an unprecedented non‐IPR hydrofullerene, C2v‐C66H4, bearing two heptagons with adjacent fused‐pentagons motif, largely dismiss this feature. Herein, employing DFT calculations, we explore the 13C‐NMR pattern and aromatic behavior of C2v‐C66H4.
The selective fusions with pyrene derivative to the rim and flank bonds of corannulene generated 4 and 7, respectively, which underwent a Scholl reaction to provide novel distorted PAHs CORA-1 and CORA-2, consisting of corannulene and dibenzocoronene units with different connections between them. The studies revealed that the properties of these PAHs are highly dependent on the fusing positions of corannulene.
Activation of the strongest triplet bond in molecular nitrogen (N2) under mild conditions is particularly challenging. Recently, its fixation and reduction were achieved by highly reactive dicoordinated borylene species at ambient conditions, ripping the limits of harsh reaction conditions by metallic species. Less reactive species with a facile preparation could be desirable for next-generation N2 activation. Now density functional theory calculations reveal that tricoordinated boranes could be a potential candidate of N2 activation/functionalization.
Aromaticity is one of the most basic concepts in organic chemistry. The planar Möbius aromatic metallapentalynes and metallapentalenes have been attracted considerable attention in the past few years. However, the aromaticity of metallapentalenes containing heteroatoms (such as B, N, and O), termed as hetero‐metallapentalenes, is rarely studied. Here, we theoretically investigated the stability and aromaticity of a series of hetero‐metallapentalenes.
Molecular nitrogen (N2), an abundant component of the atmosphere, is appealing for industrial value‐added products. However, its intrinsic inertness limits its activation to mainly metallic species. Environmental concerns and harsh reaction conditions have resulted in a demand for alternate nonmetallic and nontoxic routes to activate and functionalize N2 at ambient conditions. Comprehensive density functional theory (DFT) calculations are performed on N2 activation by boron species, specifically for the experimentally more accessible tricoordinated boron compounds.
Metallaaromatics have attracted considerable attention in recent years because they can display properties of both organic and organometallic species. However, it remains unclear whether Clar’s rule could be applied to organometallic chemistry despite its proposal in 1950s. Here, we investigate the relative stabilities of 49 organic and organometallic species by density functional theory (DFT) calculations.
Pentafulvenes are dipolar hydrocarbons since they shift their π-electrons to achieve Hückel aromaticity and thus the electron donating groups at the exocyclic position can enhance their aromaticity. Silapentafulvenes are analogues of pentafulvene formed by the replacement of the carbon atoms at the exocyclic CC double bond with a silicon atom in pentafulvene. It remains unclear how the aromaticity of 5-silapentafulvenes and 6-silapentafulvenes can be changed due to the polarization of the CSi double bond.