Planar Möbius-Aromatic Metallaborocycles

  • Author: ChemistryViews.org
  • Published: 17 February 2020
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
  • Source / Publisher: Journal of the American Chemical Society/ACS Publications
  • Associated Societies: American Chemical Society (ACS), USA
thumbnail image: Planar Möbius-Aromatic Metallaborocycles

Möbius aromaticity is a special type of aromaticity that usually exists in twisted organic molecules that resemble a Möbius strip. The rules for the number of electrons in their π-system are the opposite of "normal" Hückel aromatics: Systems with 4n π-electrons are aromatic, while those with 4n+2 π-electrons are anti-aromatic (with n being a positive integer).


The twist in the molecules causes a phase change in its p-orbitals, which allows for the Möbius aromaticity. Thus, there usually are no planar Möbius-aromatic systems. However, if the molecule contains a transition-metal atom, the phase change can be induced by a d-orbital without any twist in the structure. This makes Möbius aromaticity possible in a planar ring.


Lai-Sheng Wang, Brown University, Providence, RI, USA, and colleagues have observed the first planar monocyclic metallaboron system with Möbius aromaticity, ReB4 (pictured). The team ablated a target made of Re, B, and Ag as a binder with a laser to synthesize the desired compound. They used a high-resolution photoelectron spectroscopy setup to characterize the products.


The researchers found two rhenium-boride clusters: ReB3, which has a pyramidal structure, and ReB4, which has a planar pentagonal structure with four π-electrons. Calculations of the chemical shifts confirm the Möbius-aromatic properties of ReB4. According to the team, the results indicate that there could be a new class of Möbius-aromatic metallaborons with other metals.


 

 

Article Views: 860

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

Bookmark and Share

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more


CONNECT:

ChemistryViews.org on Facebook

ChemistryViews.org on Twitter ChemistryViews.org on YouTube ChemistryViews.org on LinkedIn Sign up for our free newsletter


A product of ChemPubSoc Europe (16 European Chemical Societies)published by Wiley-VCH