# Impact of Bulky Substituents on the Singlet Arylnitrene Ring Enlargement

## TL;DR

This paper explores how bulky chemical groups affect the formation of certain reactive molecules called arylnitrenes and their transformation into didehydroazepines.

## Contribution

The study compares computed energy surfaces to show that bulky substituents do not significantly alter the formation rates of didehydroazepines.

## Key findings

- Bulky substituents like hydrindacene do not significantly change didehydroazepine formation rates.
- Didehydroazepines may act as intermediates in forming stable triplet arylnitrenes.
- Triplet arylnitrenes can be isolated from aryl azide photodecomposition.

## Abstract

Substituents of the
hydrindacene type allow the isolation of crystalline
stable triplet arylnitrenes from photodecomposition of the corresponding
aryl azides, while phenyl azide is known to produce singlet phenylnitrene
that reacts to didehydroazepine via benzazirine. Comparison of computed
potential energy surfaces for ring enlargement of singlet arylnitrenes
suggests that bulky groups of the hydrindacene type should not significantly
change the rates of formation of didehydroazepines compared to phenylnitrene.
Thus, didehydroazepines could be trappable intermediates en route
to stable triplet arylnitrenes.