Vibrational analysis of 2-nitrophenol. A joint FT-IR, FT-Raman and scaled quantum mechanical study

FT-IR (gas, solution, solid) and FT-Raman (solution, solid) spectra of 2-nitrophenol have been recorded in the range of 4000–30 cm−1. The spectra were interpreted with the aid of normal coordinate analysis based on a scaled Becke3–Lee–Yang–Parr/6-31G* density functional force field utilising a set of scale factors introduced recently by Rauhut and Pulay (G. Rauhut, P. Pulay, J. Phys. Chem. 99 (1995) 3093). These scale factors, developed on a small training set of organic molecules containing no hydrogen bonding moieties, were found to be well transferable to 2-nitrophenol including the strong intramolecular (O)H⋯O(N) hydrogen bonding moiety as well. The scaled force field reproduced the experimental frequencies of the molecule by a weighted mean deviation of 10.5 cm−1. Based on the calculated results, 38 fundamentals from a total of 39 were identified and assigned, revising the assignments of earlier experimental studies for several fundamentals.