Photo-induced intramolecular hydrogen transfer in ortho-nitroaniline: A matrix-isolation infrared spectroscopic and quantum-chemical study

The photo-induced intramolecular hydrogen transfer in ortho-nitroaniline (ortho-NA) was investigated by matrix isolation infrared spectroscopy and quantum chemical calculations. Under UV irradiation of ortho-NA in solid argon, the hydrogen atom transferred isomer was formed. It was found that the isomer is stable and not rearranged to its nitro form upon diffusion annealing at 30 K. The infrared spectra and vibrational frequency assignments of the newly observed isomer were reported, which were supported by quantum chemical calculations.

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► The hydrogen transfer product (HT) of ortho-nitroaniline (ortho-NA) was trapped firstly.
► No conversion of the HT back to ortho-NA after annealing at 30 K, different from that of ortho-nitrotoluene.
► An excited TS structure between HT and ortho-NA.