Structure, vibrational spectroscopy, and photochemistry of 5-phenoxy-1-phenyltetrazole in argon and nitrogen cryomatrices

The molecular structure, infrared spectra, and photochemistry of 5-phenoxy-1-phenyltetrazole (5PPT) isolated in argon and N-2 cryogenic matrices were investigated by infrared spectroscopy and theoretical calculations (DFT(B3LYP)/6-311++ G(d,p)). Calculations yield two dissimilar minima on the potential energy surface of the molecule, both being eightfold degenerate by symmetry and belonging to the C-1 symmetry point group. Extensive analysis of the potential energy landscape of the molecule was performed. Upon consideration of the zero-point vibrational correction to the energy, the calculations predict that the higher energy minimum shall relax barrierlessly to the lower energy form, leading to conclude that the compound exists in a single conformer in the gas phase. Accordingly, a single conformer was observed and fully characterized spectroscopically upon isolation of the monomer of the compound in argon and nitrogen cryomatrices. UV-laser irradiation (lambda = 250 nm) of matrix-isolated 5PPT leads to photocleavage of the tetrazole ring, with release of N-2 and formation of the corresponding carbodiimide.