Theoretical study on the mechanism for the reaction of pentafulvenone with HNC in singlet and triplet states, interconversions and solvation effect

Abstract

The mechanism for the reaction of pentafulvenone with HNC in singlet and triplet states is studied theoretically at MP2/6-311+G**//B3LYP/6-311+G** level. Eleven singlet and two triplet stable points, 21 singlet and 11 triplet transition states are found. The results show that the reaction has two attacking modes, which are HNC attacking carbon–oxygen and carbon–carbon double bond of pentafulvenone. The reaction is more favourable in singlet state, and the dominant pathway is to form cyclopentadienyl isocyanide P via TS6. The structure of the most stable product is identified. The interconversions between cyclopentadienyl isocyanides and cyclopentadienyl cyanides are thoroughly studied in the singlet state. In aqueous solvent, the reaction of pentafulvenone with HNC are investigated using the PCM-UAHF model at the MP2 (PCM)/6-311+G**//B3LYP (PCM)/6-311+G** and MP2 (PCM)/6-311+G**//B3LYP/6-311+G** levels. The barrier of the transition state in the main pathway is decreased.