Knowledge Bank

The structure of the intramolecular hydrogen bond of 2-nitrophenol is being studied with the primary interest in the determination of the phenol O-H bond length. Other systems exhibiting an intramolecular hydrogen bond have been shown to have an O-H bond length longer than that normally found for the free O-H group. The microwave spectra of the normal species of 2-nitrophenol, of 2-nitrophenol-d and of 2-nitrophenol$-018$ have been assigned and the moments of inertia for the ground state have been calculated. Because the phenol oxygen is situated close to the b-axis, it is necessary to assign the doubly substituted species, 2-nitrophenol$-018$-d in order to calculate its coordinates. Work on this species is in progress. In addition to the ground state assignments, four excited vibrational states of a series have been assigned for the normal species. These vibrational satellites appear to be due to torsion of the nitro group. This work supported by a grant C-071 of the Robert A. Welch Foundatation.