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Insights into the Thermal and Photochemical Reaction Mechanisms of Azidoacetonitrile. Spectroscopic and MS‐CASPT2 Calculations
Author(s) -
Algarra Manuel,
Soto Juan
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000201
Subject(s) - chemistry , nitrene , conical intersection , complete active space , photochemistry , singlet state , computational chemistry , ab initio , thermal decomposition , ground state , photodissociation , dissociation (chemistry) , imine , photoisomerization , isomerization , excited state , density functional theory , basis set , molecule , atomic physics , organic chemistry , physics , catalysis
This work studies the photochemical and thermal decompositions of azidoacetonitrile (N 3 CH 2 CN) from both the experimental and theoretical points of view. The data of the photochemical experiments are taken from the literature, while the thermal decomposition have been carried out by us. In addition, we have performed ab initio calculations of the multiconfigurational type [complete active space self‐consistent field (CASSCF) and the multistate multireference perturbation theory (MS‐CASPT2)]. It is found that the first step of both type of decompositions is N 2 elimination and formation of closed shell singlet nitrene. Afterwards, the nitrene tends to rapidly rearrange into formimidoyl cyanide (HNCHCN). As both reactions progress, the imine isomerizes into formimidoyl isocyanide (HNCHNC). The photoisomerization of the imine takes places thorough a conical intersection, while the same reaction on the ground electronic state occurs via a conventional transition state. The last step of the global reaction is decomposition of the imines into HCN and CNH. In photochemical conditions, the conjunction of the imines and its dissociation products (HCN and CNH) yields adenine