Low-temperature ozonation (-78 °C) of saturated organic compounds, i.e., alcohols, ethers, acetals, hydrocarbons, and organometallic hydrides leads to the corresponding hydrotrioxides (ROOOH), and dihydrogen trioxide (HOOOH) as unstable intermediates [1, 2]. These polyoxides have been well characterized by ¹H, ¹³C, ¹⁷O and ²⁹Si NMR, and by IR spectroscopic methods [3]. Furthermore, the structure of HOOOH has recently been determined by microwave spectroscopy [4]. According to the theoretical studies, they form dimeric as well as polymeric structures in »inert«, i.e., non-basic solvents, such as dichloromethane, toluene, chloroform, and benzene. However, basic solvents (acetone, methyl acetate and tert-butyl methyl ether) are able to complex with such aggregates and, if basic enough, disrupt the hydrogen bonds to form hydrogen-bonded complexes with ROOOH (HOOOH).

Pyridine N-oxides are efficient hydrogen bond acceptors [5], forming complexes with various hydrogen bond donors, such as water, (carboxylic) acids, peroxy acids, alcohols, phenols, and silanols. Therefore, they should also be able to form strong hydrogen-bonded complexes with hydrotrioxides, thus affecting their stability and reactivity. Namely the hydrotrioxides were estimated to be more acidic than their homologues, i.e., hydroperoxides and alcohols [2]. The interactions between various pairs of hydrotrioxides and pyridine N-oxides were studied by means of ¹H NMR spectroscopy. The change in kinetic and activation parameters for the decomposition of ROOOH-pyridine N-oxides complexes will be discussed and plausible binding modes will be presented. A comparison between pyridine N-oxides, phosphine oxides, and arsine oxides as suitable hydrogen bond acceptors will also be outlined.

[1] B. Plesničar, J. Cerkovnik, T. Tekavec, J. Koller, Chem. Eur. J. 2000, 6, 809.

[2] B. Plesničar, Acta Chim. Slov. 2005, 52, 1.

[3] J. Cerkovnik, T. Tuttle, E. Kraka, N. Lendero, B. Plesničar, D. Cremer, J. Am. Chem. Soc. 2006, 128, 4090.

[4] K. Suma, Y. Sumiyoshi, Y. Endo, J. Am. Chem. Soc. 2005, 127, 14998.

[5] C. Laurence, M. Berthelot, Perspect. Drug Discov. Des. 2000, 18, 39.

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