Crystal Structures of Two 1,4-diamino-1,2,4-triazolium Salts

Bis(1,4-diamino-1,2,4-triazolium) sulfate (1) was obtained from the corresponding chloride by ion metathesis using Ag 2 SO 4. Further metathesis with barium 5,5 1-azotetrazolate yielded bis(1,4-diamino-1,2,4-triazolium) 5,5 1-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.

N,N 1 -Diaminoazolium cations are potent hydrogen bond donors [2,[8][9][10], and it seemed to be of interest to examine the interactions of the 1,4-diamino-1,2,4-triazolium cation with acceptor anions such as sulfate or 5,5 1 -azotetrazolate in the solid state.The crystal data and refinement details are summarized in Table 1.
Crystals 2016, 6, 13 2 of 7 such as sulfate or 5,5′-azotetrazolate in the solid state.The crystal data and refinement details are summarized in Table 1.Hydrogen atoms at N3 and N5 were found and refined isotropically.The geometry of the N-amino groups was pyramidal, indicating sp 3 hybridization.The N-amino group conformations relative to the azolium ring planes were eclipsed (lone pair closely aligned with the ring plane, N-H bonds out of the ring plane), as observed in the structure of the corresponding chloride (Cambridge Structural Database reference code MEBPOZ).
The crystal structure of this simple salt was found to be unexpectedly complicated.There are four independent cations and two anions in the asymmetric unit.Numerous NH¨¨¨O hydrogen bonds (Table 2) create a three-dimensional framework.These interactions are depicted separately, for the sake of clarity, for each of the four independent cations A-D in Figure 2. The salt (C 2 H 6 N 5 ) 2 (C 2 N 10 ) consists of 76.9 percent nitrogen and thus can be rightly considered to be "nitrogen-rich."The hydrogen atoms at N8 and N10 were found and refined isotropically with bond restraints, and the N-amino groups again are pyramidal.The ions form cyclic hydrogen-bonded assemblies (Figure 3), which can be described by a R 2 2 p13q graph set [11], meaning a 13-membered ring with 2 hydrogen bond donors and 2 acceptors.In contrast, in the structure of the related 1,3-diaminoimidazolium 5,5 1 -azotetrazolate (CSD reference code YEHTAI) [8] hydrogen bonds between two cations and two anions create centrosymmetric ring-shaped aggregates, graph set R 4 4 p20q.In 2, a wave-like arrangement of the ions is observed (Figure 3), whereas the very similar salt, 4-amino-1-methyl-1,2,4-triazolium 5,5 1 -azotetrazolate (CSD reference code PAPMOJ), packed in flat layers and crystallized in an orthorhombic space group [7].Obviously, the structure of 2 is controlled by the additional hydrogen bonding of the second amino group.
crystallized in an orthorhombic space group [7].Obviously, the structure of 2 is controlled by the additional hydrogen bonding of the second amino group.

Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA)
Thermoanalysis of the triazolium salts 1 and 2 showed initial melting followed by exothermal decomposition (maxima at 164 and 165 °C) with approximately 60% loss of mass.Decomposition gases are not limited to N2, but also include NH3, CH4 and HCN [6], which are formed in varying amounts.Thermograms are depicted in Figure 4.

Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA)
Thermoanalysis of the triazolium salts 1 and 2 showed initial melting followed by exothermal decomposition (maxima at 164 and 165 ˝C) with approximately 60% loss of mass.Decomposition gases are not limited to N 2 , but also include NH 3 , CH 4 and HCN [6], which are formed in varying amounts.Thermograms are depicted in Figure 4.
Single crystal diffraction intensity data were recorded by ω scans with an Oxford Diffraction Gemini-R Ultra (Oxford Diffraction Ltd., Abingdon, Oxfordshire, UK) or by φ and ω scans with a Bruker D8 Quest Photon 100 (Billerica, MA, USA) diffractometer using MoKα radiation.CCDC reference numbers: 1441522 and 1441523.These data can be obtained free of charge from The Cambridge Crystallographic Data Centre (Cambridge, UK).
Single crystal diffraction intensity data were recorded by ω scans with an Oxford Diffraction Gemini-R Ultra (Oxford Diffraction Ltd., Abingdon, Oxfordshire, UK) or by ϕ and ω scans with a Bruker D8 Quest Photon 100 (Billerica, MA, USA) diffractometer using MoKα radiation.CCDC reference numbers: 1441522 and 1441523.These data can be obtained free of charge from The Cambridge Crystallographic Data Centre (Cambridge, UK).

Table 1 .
Crystal data and structure refinement for 1 and 2.

Table 1 .
Crystal data and structure refinement for 1 and 2.