Henry Rzepa's Blog Chemistry with a twist

April 15, 2016

Azane oxide, a tautomer of hydroxylamine.

In the previous post I described how hydronium hydroxide or H3O+…HO, an intermolecular tautomer of water, has recently been observed captured inside an organic cage[1] and how the free-standing species in water can be captured computationally with the help of solvating water bridges. Here I explore azane oxide or H3N+-O, a tautomer of the better known hydroxylamine (H2N-OH).



  1. M. Stapf, W. Seichter, and M. Mazik, "Unique Hydrogen-Bonded Complex of Hydronium and Hydroxide Ions", Chemistry - A European Journal, vol. 21, pp. 6350-6354, 2015. http://dx.doi.org/10.1002/chem.201406383

October 1, 2015

Yes, no, yes. Computational mechanistic exploration of (nickel-catalysed) cyclopropanation using tetramethylammonium triflate.

A fascinating re-examination has appeared[1] of a reaction first published[2] in 1960 by Wittig and then[3] repudiated by him in 1964 since it could not be replicated by a later student. According to the new work, the secret to a successful replication seems to be the presence of traces of a nickel catalyst (originally coming from e.g. a nickel spatula?). In this recent article[1] a mechanism for the catalytic cycle is proposed. Here I thought I might explore this mechanism using calculations to see if any further insights might emerge.



  1. S.A. Künzi, J.M. Sarria Toro, T. den Hartog, and P. Chen, "Nickel-Catalyzed Cyclopropanation with NMe4 OTf and n BuLi", Angewandte Chemie International Edition, vol. 54, pp. 10670-10674, 2015. http://dx.doi.org/10.1002/anie.201505482
  2. V. Franzen, and G. Wittig, "Trimethylammonium-methylid als Methylen-Donator", Angewandte Chemie, vol. 72, pp. 417-417, 1960. http://dx.doi.org/10.1002/ange.19600721210
  3. G. Wittig, and D. Krauss, "Cyclopropanierungen bei Einwirkung vonN-Yliden auf Olefine", Justus Liebigs Annalen der Chemie, vol. 679, pp. 34-41, 1964. http://dx.doi.org/10.1002/jlac.19646790106

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