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Title: Approaching Dianionic Tetraoxadiborecine Macrocycles: 10‐Membered Bora‐Crown Ethers Incorporating Borafluorenate Units
Abstract

The addition of non‐benzenoid quinones, acenapthenequinone or aceanthrenequinone, to the 9‐carbene‐9‐borafluorene monoanion (1) affords the first examples of dianionic 10‐membered bora‐crown ethers (25), which are characterized by multi‐nuclear NMR spectroscopy (1H,13C,11B), X‐ray crystallography, elemental analysis, and UV/Vis spectroscopy. These tetraoxadiborecines have distinct absorption profiles based on the positioning of the alkali metal cations. When compound4, which has a vacant C4B2O4cavity, is reacted with sodium tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate, a color change from purple to orange serves as a visual indicator of metal binding to the central ring, whereby the Na+ion coordinates to four oxygen atoms. A detailed theoretical analysis of the calculated reaction energetics is provided to gain insight into the reaction mechanism for the formation of25. These data, and the electronic structures of proposed intermediates, indicate that the reaction proceeds via a boron enolate intermediate.

 
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Award ID(s):
2046544 2018870
NSF-PAR ID:
10388039
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Angewandte Chemie International Edition
Volume:
62
Issue:
5
ISSN:
1433-7851
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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