Wydział Chemii

Magdalena Sałdyka

Zofia Mielke

2005

Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy

61

1491-1497

10.1016/j.saa.2004.11.006

Naukowa

Angielski

Artykuł

Dimerization of the keto tautomer of acetohydroxamic acid has been studied using FTIR matrix isolation spectroscopy and DFT(B3LYP)/6-31+G(d,p) calculations. Analysis of CH₃CONHOH/Ar matrix spectra indicates formation of two dimers in which two intramolecular CO···HON bonds within two interacting acetohydroxamic acid molecules are retained. A chain dimer I is stabilized by the intermolecular CO···HN hydrogen bond, whereas the cyclic dimer II is stabilized by two intermolecular NH···O(H)N bonds. Twelve vibrations were identified for dimer I and six vibrations for dimer II; the observed frequency shifts show a good agreement with the calculated ones for the structures I and II. Both dimers have comparable binding energies ( = −7.02, −6.34 kcal mol⁻¹) being less stable than calculated structures III and IV ( = −9.50, −8.87 kcal mol⁻¹) in which one or two intramolecular hydrogen bonds are disrupted. In the most stable 10-membered cyclic dimer III, two intermolecular CO···HON hydrogen bonds are formed at expense of intramolecular hydrogen bonds of the same type. The formation of the less stable (AHA)₂ dimers in the studied matrixes indicates that the formation of (AHA)₂ is kinetically and not thermodynamically controlled.

Acetohydroxamic acid, Molecular aggregates, Hydrogen bonding, Infrared spectroscopy, Matrix isolation, Computational methods

https://doi.org/10.1016/j.saa.2004.11.006

http://www.elsevier.com