Ultrafast protonation of cyanate anion in aqueous solution Academic Article uri icon

abstract

  • We use femtosecond infrared spectroscopy to study the aqueous protonation dynamics of cyanate, OCN−, using a photoacid, 2‐naphthol‐6,8‐disulfonate (2N‐6,8S) excited by a 60‐fs pulse tuned at 336 nm. The transient response in the spectral range of the cyano‐stretching vibrational marker modes of cyanic acid, HOCN, and isocyanic acid, HNCO, reveals how much of both reaction products are formed at early delay times, and whether the on‐contact reactive complex between 2N‐6,8S and OCN− has a well‐defined structure. Using the Szabo‐Collins‐Kimball approach to describe bimolecular reaction dynamics subject to the Debye‐von Smoluchowski diffusional motions, an on‐contact proton transfer reaction rate is derived that follows the correlation between free energy and reaction rates found for a large class of aqueous proton transfer of photoacid dissociation and photoacid‐base neutralization reactions.

publication date

  • January 1, 2009