Special Issue "Nitrogen-Rich Salts"

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (31 December 2015)

Special Issue Editor

Guest Editor
Dr. Gerhard Laus

Center for Chemistry and Biomedicine, University of Innsbruck, 6020 Innsbruck, Austria
Website | E-Mail
Interests: heterocyclic chemistry, ionic liquids, NMR spectroscopy, nitrogen-rich salts, hydrogen bonding, halogen interactions in the solid state.

Special Issue Information

Dear Colleagues,

The designability of salts (choice of cations and anions, functional groups) provides ample opportunities for tailoring their properties. Highly energetic salts are obtained when both the cation and the anion are nitrogen-rich species. These salts possess advantages over non-ionic energetic molecules due to their lower vapor pressures and higher densities. They often exhibit enhanced thermal stability. From the viewpoint of practical applications, these features allow the development of new generations of materials. Nitrogen-rich metal salts have potential as precursors of functional materials, for example in the synthesis of low-density, nanoporous metal foams. In any case, the structural characterization of these versatile salts by X-ray diffraction can be expected to reveal intriguing and gratifying results. Even serendipitous discoveries inspire stimulatory feedback for the understanding and designing of energetic materials. In this context, phlegmatization is another relevant field of interest. The current volume ‘Nitrogen-Rich Salts’ provides a unique forum allowing the dissemination of results in the entire field. Scientists working in a broader sense on nitrogen-rich salts are invited to use this opportunity for presenting their suitable contributions.

The topics summarized under the keywords should be considered only as guidelines. The volume is open for any advanced topics in the field of Nitrogen-Rich Salts.

Dr. Gerhard Laus
Guest Editor

Manuscript Submission Information

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Keywords

  • energetic salts
  • propellants
  • explosives
  • gas generators
  • thermal stability
  • technical applications
  • materials science
  • phlegmatization

Published Papers (5 papers)

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Research

Open AccessArticle 2-Azidoimidazolium Ions Captured by N-Heterocyclic Carbenes: Azole-Substituted Triazatrimethine Cyanines
Crystals 2016, 6(4), 40; doi:10.3390/cryst6040040
Received: 29 January 2016 / Revised: 15 February 2016 / Accepted: 17 February 2016 / Published: 8 April 2016
PDF Full-text (2063 KB) | HTML Full-text | XML Full-text
Abstract
1,3-Disubstituted 2-azidoimidazolium salts (substituents = methyl, methoxy; anion = PF6) reacted with N-heterocyclic carbenes to yield yellow 2-(1-(azolinylidene)triazen-3-yl)-1,3-R2-imidazolium salts (azole = 1,3-dimethylimidazole, 1,3-dimethoxyimidazole, 4-dimethylamino-1-methyl-1,2,4-triazole; R = methyl, methoxy; anion = PF6). Crystal structures of three cationic
[...] Read more.
1,3-Disubstituted 2-azidoimidazolium salts (substituents = methyl, methoxy; anion = PF6) reacted with N-heterocyclic carbenes to yield yellow 2-(1-(azolinylidene)triazen-3-yl)-1,3-R2-imidazolium salts (azole = 1,3-dimethylimidazole, 1,3-dimethoxyimidazole, 4-dimethylamino-1-methyl-1,2,4-triazole; R = methyl, methoxy; anion = PF6). Crystal structures of three cationic triazenes were determined. Numerous interionic C–H···F contacts were observed. Solvatochromism of the triazenes in polar solvents was investigated by UV-Vis spectroscopy, involving the dipolarity π* and hydrogen-bond donor acidity α of the solvent. Cyclovoltammetry showed irreversible reduction of the cations to uncharged radicals. Thermoanalysis showed exothermal decomposition. Full article
(This article belongs to the Special Issue Nitrogen-Rich Salts)
Figures

Open AccessArticle Preparation, Crystal and Properties of Nitrogen-Rich Energetic Salt of Bis(semicarbazide) 5,5′-Bitetrazole-1,1′-diolate
Crystals 2016, 6(2), 21; doi:10.3390/cryst6020021
Received: 26 December 2015 / Accepted: 3 February 2016 / Published: 6 February 2016
Cited by 4 | PDF Full-text (2297 KB) | HTML Full-text | XML Full-text
Abstract
A novel energetic salt of Bis(semicarbazide) 5,5′-bitetrazole-1,1′-diolate [2(SCZ)·BTO] was synthesized by using semicarbazide hydrochloride and 1H,1’H-5,5’-bitetrazole-1,1’-diol (BTO) as raw materials, and its structure was characterized by elemental analysis, Fourier Transform infrared spectroscopy (FT-IR) spectroscopy, 13C NMR spectrum and
[...] Read more.
A novel energetic salt of Bis(semicarbazide) 5,5′-bitetrazole-1,1′-diolate [2(SCZ)·BTO] was synthesized by using semicarbazide hydrochloride and 1H,1’H-5,5’-bitetrazole-1,1’-diol (BTO) as raw materials, and its structure was characterized by elemental analysis, Fourier Transform infrared spectroscopy (FT-IR) spectroscopy, 13C NMR spectrum and mass spectrum. The single crystal of the title salt was obtained and its structure was determined by an X-ray single-crystal diffractometer. Results show that 2(SCZ)·BTO belongs to the monoclinic space group P21/c with a density of 1.685 g·cm−3. The thermal decomposition behavior was investigated by differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) analyses, and non-isothermal kinetic parameters were also calculated. The results indicated that it has a good thermal stability with a decomposition temperature above 200 °C. The apparent activation energies were 231.2 kJ·mol−1 (Kissinger's method) and 228.1 kJ·mol−1 (Ozawa-Doyle's method), respectively, and the critical temperature of thermal explosion is 240.6 °C. The enthalpy of formation for the salt was calculated as 158.1 kJ·mol−1. The detonation pressure (P) and detonation velocities (D) of the salt were determined by using the Kamlet-Jacobs equation. The results indicated that the title salt has potential applications in the field of energetic materials. Full article
(This article belongs to the Special Issue Nitrogen-Rich Salts)
Figures

Open AccessFeature PaperArticle 5-Azido-4-dimethylamino-1-methyl-1,2,4-triazolium Hexafluoridophosphate and Derivatives
Crystals 2016, 6(2), 20; doi:10.3390/cryst6020020
Received: 14 January 2016 / Revised: 1 February 2016 / Accepted: 2 February 2016 / Published: 5 February 2016
Cited by 1 | PDF Full-text (9682 KB) | HTML Full-text | XML Full-text
Abstract
5-Azido-4-(dimethylamino)-1-methyl-1,2,4-triazolium hexafluoridophosphate was synthesized from the corresponding 5-bromo compound with NaN3. Reaction with bicyclo[2.2.1]hept-2-ene yielded a tricyclic aziridine, addition of an N-heterocyclic carbene resulted in a triazatrimethine cyanine, and reduction with triphenylphosphane gave the 5-amino derivative. The crystal structures of
[...] Read more.
5-Azido-4-(dimethylamino)-1-methyl-1,2,4-triazolium hexafluoridophosphate was synthesized from the corresponding 5-bromo compound with NaN3. Reaction with bicyclo[2.2.1]hept-2-ene yielded a tricyclic aziridine, addition of an N-heterocyclic carbene resulted in a triazatrimethine cyanine, and reduction with triphenylphosphane gave the 5-amino derivative. The crystal structures of three nitrogen-rich salts were determined. Thermoanalysis of the cationic azide and triazene showed exothermal decomposition. The triazene exhibited negative solvatochromism in polar solvents involving the dipolarity π* and hydrogen-bond donor acidity α of the solvent. Full article
(This article belongs to the Special Issue Nitrogen-Rich Salts)
Open AccessArticle Crystal Structures of Two 1,4-Diamino-1,2,4-triazolium Salts
Crystals 2016, 6(1), 13; doi:10.3390/cryst6010013
Received: 30 December 2015 / Revised: 13 January 2016 / Accepted: 18 January 2016 / Published: 20 January 2016
Cited by 1 | PDF Full-text (1570 KB) | HTML Full-text | XML Full-text
Abstract
Bis(1,4-diamino-1,2,4-triazolium) sulfate (1) was obtained from the corresponding chloride by ion metathesis using Ag2SO4. Further metathesis with barium 5,5′-azotetrazolate yielded bis(1,4-diamino-1,2,4-triazolium) 5,5′-azotetrazolate (2). Numerous NH···N and NH···O interactions were identified in the crystal structures of
[...] Read more.
Bis(1,4-diamino-1,2,4-triazolium) sulfate (1) was obtained from the corresponding chloride by ion metathesis using Ag2SO4. Further metathesis with barium 5,5′-azotetrazolate yielded bis(1,4-diamino-1,2,4-triazolium) 5,5′-azotetrazolate (2). Numerous NH···N and NH···O interactions were identified in the crystal structures of 1 and 2. Both compounds undergo exothermal decomposition upon heating. Full article
(This article belongs to the Special Issue Nitrogen-Rich Salts)
Open AccessArticle Electrostatic Potentials, Intralattice Attractive Forces and Crystal Densities of Nitrogen-Rich C,H,N,O Salts
Crystals 2016, 6(1), 7; doi:10.3390/cryst6010007
Received: 9 December 2015 / Revised: 28 December 2015 / Accepted: 30 December 2015 / Published: 4 January 2016
Cited by 8 | PDF Full-text (4623 KB) | HTML Full-text | XML Full-text
Abstract
The computed electrostatic potentials on C,H,N,O molecular solids and nitrogen-rich C,H,N,O salts are used in analyzing and comparing intralattice attractive forces and crystal densities in these two categories of compounds. Nitrogen-rich C,H,N,O salts are not an assured path to high densities. To increase
[...] Read more.
The computed electrostatic potentials on C,H,N,O molecular solids and nitrogen-rich C,H,N,O salts are used in analyzing and comparing intralattice attractive forces and crystal densities in these two categories of compounds. Nitrogen-rich C,H,N,O salts are not an assured path to high densities. To increase the likelihood of high densities, small cations and large anions are suggested. Caution is recommended in predicting benefits of nitrogen-richness for explosive compounds. Full article
(This article belongs to the Special Issue Nitrogen-Rich Salts)

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