Reconciling the Debate on the Existence of Pentazole HN5 in the Pentazolate Salt of (N5)6(H3O)3(NH4)4Cl

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Huisheng Huang
  • Jie Zhong
  • Liang Ma
  • Liping Lv
  • Joseph S. Francisco

Detail(s)

Original languageEnglish
Pages (from-to)2984–2989
Journal / PublicationJournal of the American Chemical Society
Volume141
Issue number7
Online published31 Jan 2019
Publication statusPublished - 20 Feb 2019
Externally publishedYes

Abstract

The successful synthesis of the pentazolate salt (N5)6(H3O)3(NH4)4Cl has received considerable attention, as it ends the long search for a method for the bulk preparation of cyclo-N5-, a molecular ring with high energy density (Zhang, C.; et al. Science 2017, 355, 374.). A debate has recently arisen on the possible existence of a neutral HN5 species in the pentazolate salt (Huang, R.-Y.; et al. Science 2018, 359, eaao3672.; Jiang, C.; et al. Science 2018, 359, eaas8953.). Herein, we show that the debate can be reconciled by the temperature effect on the proton transfer. At a low temperature (123 K), the proton transfer from H3O+ to cyclo-N5- is energetically unfavorable; therefore, few neutral HN5 species exist in the pentazolate salt, which is consistent with the single-crystal X-ray diffraction measurements (Zhang, C.; et al. Science 2017, 355, 374.). As the temperature increases toward room temperature, endothermic proton transfer becomes increasingly feasible, promoting the formation of H2O···HN5 via H2O-H-N5 as an intermediate species. In addition, the confusion over the apparent absence of a peak in the measured infrared spectrum corresponding to the out-of-plane bending of H3O+ can be resolved by the computationally established ultrafast interconversion among the neutral and anionic species under ambient conditions.

Citation Format(s)

Reconciling the Debate on the Existence of Pentazole HN5 in the Pentazolate Salt of (N5)6(H3O)3(NH4)4Cl. / Huang, Huisheng; Zhong, Jie; Ma, Liang et al.

In: Journal of the American Chemical Society, Vol. 141, No. 7, 20.02.2019, p. 2984–2989.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review