Simulating Non‐Adiabatic Dynamics of Photoexcited Phenyl Azide: Investigating Electronic and Structural Relaxation en Route to the Formation of Phenyl Nitrene

• Published in: Chemistry : a European journal 2024-02, Vol.30 (7), p.e202302178-n/a
• Main Authors: Das, Sambit K., Odelius, Michael, Banerjee, Ambar
• Format: Article
• Language: English
• Subjects: Adiabatic; Azides; Azides (organic); CASSCF; Chemical Physics; Density functional calculations; Dissociation; Dynamic structural analysis; Electronic structure; Excitation; kemisk fysik; Mathematical analysis; Molecular dynamics; Nitrogen; Non-adiabatic molecular dynamics; Photodissociation; Photolysis; Population dynamics; Simulation
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202302178

Excited state molecular dynamics simulations of the photoexcited phenyl azide have been performed. The semi‐classical surface hopping approximation has enabled an unconstrained analysis of the electronic and nuclear degrees of freedom which contribute to the molecular dissociation of phenyl azide into phenyl nitrene and molecular nitrogen. The significance of the second singlet excited state in leading the photodissociation has been established through electronic structure calculations, based on multi‐configurational schemes, and state population dynamics. The investigations on the structural dynamics have revealed the N−N bond separation to be accompanied by synchronous changes in the azide N−N−N bond angle. The 100 fs simulation results in a nitrene fragment that is electronically excited in the singlet manifold. Photolysis of phenyl azide lead by coupled nuclear motion results in excited singlet photoproduct. Surface hopping simulations based on multi‐reference model reveal that the second electronic excited state steers the N2 elimination, accompanied by synchronous bond elongation and angular rotation.