Related Experiment Video
Updated: Jul 11, 2025
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On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes
Published on: August 5, 2016
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Direct Spectroscopic Identification of BN-Arynes and Subtle Steric Effects on Nitrogen Fixation
Divanshu Gupta1, Constanze Keck1, Christina Tönshoff1
1Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|November 6, 2023
Summary
This study explores 1,2-azaborinines, BN analogues of arynes. Researchers generated dibenzo[c,e][1,2]azaborinine (10,9-BN-phenanthryne) via thermolysis and studied its properties under cryogenic conditions.
Area of Science:
- Organometallic Chemistry
- Boron Chemistry
- Reactive Intermediates
Background:
- 1,2-Azaborinines are isoelectronic BN analogues of arynes, representing an underexplored class of reactive intermediates.
- Dibenzo[c,e][1,2]azaborinine (10,9-BN-phenanthryne) has been previously inferred through trapping reactions.
Purpose of the Study:
- To generate and characterize 10,9-BN-phenanthryne in the gas phase and under cryogenic conditions.
- To investigate the photochemical behavior of azaborinine precursors and their adducts.
- To explore the potential for nitrogen fixation with these novel BN-aryne analogues.
Main Methods:
- Gas-phase thermolysis of the pyridine adduct of 9-azido-9-borafluorene.
- Cryogenic matrix isolation and photolysis of azidoborole precursors.
- Ionization potential measurement.
- Spectroscopic analysis (FTIR).
Main Results:
- 10,9-BN-phenanthryne was generated in the gas phase via thermolysis, with an ionization potential of 8.2 eV from its π HOMO.
- Photolysis of 9-azido-9-borafluorene under cryogenic conditions led to isomerization to the dinitrogen adduct without a triplet borylnitrene intermediate.
- Nitrogen fixation was found to be irreversible for the 10,9-BN-phenanthryne-N2 adduct under cryogenic conditions.
- Steric hindrance in tetra-tert-butyl substituted analogues precluded nitrogen fixation.
Conclusions:
- The study successfully generated and characterized 10,9-BN-phenanthryne, providing insights into its electronic properties and reactivity.
- The photochemical behavior highlights the stability of the BN-aryne core and the irreversibility of nitrogen fixation under specific conditions.
- Steric effects play a crucial role in controlling the reactivity and preventing nitrogen fixation in substituted azaborinines.
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