The near-infrared spectrum of ONNHF—direct evidence for geometric isomerism in a hydrogen bonded complex

The near-IR spectrum and equilibrium structure of a novel hydrogen bonded complex between nitrous oxide and hydrogen fluoride is described. In contrast to a previously reported structure, in which the HF bonds to the oxygen end of NNO, the present structure has the HF bonded to the nitrogen end of NNO. The structure is unambiguously confirmed by isotopic substitution. The identification of the two stable, spectroscopically distinct structures represents the first demonstration of geometric isomerism in a hydrogen-bonded complex.