supporting information

Acta Cryst. (2013). E69, o1131-o1132    [ doi:10.1107/S1600536813016589 ]

4,5-Di­amino-3-[(E,E)-4-(4,5-di­amino-4H-1,2,4-triazol-3-yl)buta-1,3-dien­yl]-4H-1,2,4-triazol-1-ium chloride

R. Centore and V. Piccialli

Abstract top

The title compound, C8H13N10+·Cl-, is the monochlorhydrate salt of an aromatic bis­(di­amino­triazole). The cation is centrosymmetric, lying about an inversion centre (Ci symmetry) because the acidic H atom is disordered over two centrosymmetrically related ring N atoms, with equal multiplicity. It is noteworthy that protonation occurs at an N atom of the ring, instead of at the C-NH2 or N-NH2 amino groups. The chloride anions are also in special positions, as they lie on binary axes, and so the crystallographically independent unit contains half of a formula unit. The N atom of the C-NH2 group is sp2-hybridized and the amino group is coplanar with the triazole ring [dihedral angle = 5 (3)°], while the N atom of the N-NH2 amino group is pyramidal. The C=C bonds are in E conformations and the cation is flat because the conformation of the carbon chain is fully extended. The chloride anions are hexa­coordinated, in a distorted trigonal-prismatic geometry, and they are involved, as acceptors, in six hydrogen bonds. Chains of hydrogen-bonded cations, running along c and a + c, are generated by c-glide and C2 rotation, respectively. This combination of N-H...Cl and N-H...N hydrogen bonds leads to the formation of a three-dimensional network.

Comment top

Nitrogen rich, aromatic heterocycles have interest in the field of organic electronics for several reasons. One reason is that the Bondi van der Waals radius of nitrogen is 1.55 Å, as compared with 1.70 Å of carbon, so while the limiting interlayer distance for an all-carbon-containing planar structure is that of graphite (3.4 Å), in planar structures containing sp2 hybridized nitrogen atoms, interplanar distances of 3.1 Å can be reached in principle. Another feature of sp2 nitrogen atoms in heteroaromatic compounds is their capability of acting as H bonding acceptors, a feature that, if properly exploited, can lead to tighter packings. Following our interest in the synthesis of aromatic heterocycles for advanced applications in electronics, optoelectronics and photonics (Carella, Centore, Fort et al., 2004; Centore, Ricciotti et al., 2012; Centore, Concilio et al., 2012), we have recently developed the synthesis on N-rich heterocycles containing the 3,4-diamino-1,2,4-triazole unit (Centore et al., 2011; Centore, Fusco, Capobianco et al., 2013). In the present paper we report the structural investigation of the title compound, shown in the Scheme, which is the monochlorhydrate salt of a bis(3,4-diamino-1,2,4- triazole).

The molecular structure is shown in Fig. 1. The cation is formed by protonation at N2 atom of the ring, instead of C–NH2 or N—NH2 amino groups. The acidic H atom is found bonded both to N2 and to N2i (i= -x + 1/2, -y + 1/2, -z + 1) with equal multiplicity which is 0.5 since the cation lies in special position on crystallographic inversion centres and has (statistically) Ci symmetry. The chloride anion also lies in special position on C2 axes and has fixed occupancy factor 0.5 too. The geometry around N5 atom is substantially planar indicating sp2 hybridization (the sum of valence angles at N5 is 360 (3)°) and the plane of the amino group is coplanar with the triazole ring. This suggests partial delocalization of the lone pair of N5 towards the triazole ring, as confirmed by the short length of the bond C1–N5 (1.329 (3) Å). The geometry around N4, on the other hand, is pyramidal (the sum of valence angles at N4 is 318 (4)°). With exception for the two H atoms bonded to N4, the molecule is substantially flat, as the result of the torsion angles of the hydrocarbon chain joining the two rings. The double bonds in the hydrocarbon chain are in E configuration.

The molecules of the title compound have several H bonding donor and acceptor groups, and the crystal packing is dominated by the formation of H bonds, Table 1. Several H bonding motifs are recognized in the crystal packing and some of them are shown in Figs. 2. The chloride anion is hexacoordinated, according to a distorted trigonal prismatic geometry; it is involved, as acceptor, in six H bonds: four are formed with C–NH2 donors and two with N–NH2 donors. Ring patterns R23(10) and R24(8) are observed.

Cations are involved in the formation of different H bonded chains. Chains running along c are generated by the c-glide reflection through H bonding between a N–NH2 donor and N1 acceptor of another glide-related molecule. The graph-set symbol of the H bonding pattern is C(5). Chains running along a + c are formed by H bonding between N2–H donor and N2 acceptor of a C2 related molecule. The graph-set symbol of the H bonding pattern is C(11). It is a remarkable finding that the crystal structure of the dichlorhydrate salt is completely different, showing the formation of π-stacked infinite planar layers (Centore, Fusco, Carella & Causà, 2013).

Related literature top

For semiconductor, optoelectronic and piezoelectric materials containing heterocycles, see: Wen & Liu (2010); Centore, Ricciotti et al. (2012); Centore, Concilio et al. (2012). For the structural analysis of conjugation in organic molecules containing N-rich heterocycles, see: Carella, Centore, Fort et al. (2004); Centore, Fusco, Capobianco et al. (2013). For the synthesis of related compounds, see: Centore et al. (2011). For the local packing modes of heterocycles containing nitrogen, see: Centore et al. (2013a,b). For H bonding in crystal structures, see: Centore, Fusco, Jazbinsek et al. (2013). For the crystal structure of the dichlorhydrate salt, see: Centore, Fusco, Carella & Causà (2013).

Experimental top

The title compound was prepared by suspending E,E-1,4-bis(3,4-diamino-1,2,4-triazol-5-yl)-1,3-butadiene (Centore et al., 2011) in diluted hydrochloric acid (0.1 M). By heating the suspension at ebullition, a clear solution was obtained. By adding ethanol, single crystals of the chlorhydrate were obtained by slow cooling to room temperature.

Refinement top

The H atoms bonded to N atoms were located in difmaps and their coordinates were refined. All other H atoms were generated stereochemically and were refined by the riding model. For all H atoms Uiso=1.2×Ueq of the carrier atom was assumed. The cation (C8H13N10)+ is not centrosymmetric by itself. However, since the acidic H atom is equally shared by N2 and N2i (i= -x + 1/2, -y + 1/2, -z + 1) the cation is statistically centrosymmetric (Ci crystallographic symmetry). For this reason the occupancy factor of the H atom bonded to N2 was fixed at 0.5. Chloride anions lie in special positions on binary axes and they too were given fixed occupancy factor 0.5.

Computing details top

Data collection: COLLECT (Nonius, 1999); cell refinement: DIRAX/LSQ (Duisenberg et al., 2000); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top
[Figure 1] Fig. 1. ORTEP view of the molecular structure of the title compound. Thermal ellipsoids are drawn at 30% probability level. The acidic H atom is disordered over N2 and N2i (i= -x + 1/2, -y + 1/2, -z + 1) with occupancy factor 0.5. The chloride anion also has occupancy factor 1/2, as it lies on C2 axes.
[Figure 2] Fig. 2. Partial crystal packing of the title compound, showing some H bonding patterns. H bonds are represented by dashed lines. Only one position of the disordered N+–H hydrogen atom is shown.
4,5-Diamino-3-[(E,E)-4-(4,5-diamino-4H-1,2,4-triazol-3-yl)buta-1,3-dienyl]-4H-1,2,4-triazol-1-ium chloride top
Crystal data top
C8H13N10+·ClF(000) = 592
Mr = 284.73Dx = 1.532 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 150 reflections
a = 10.360 (3) Åθ = 3.7–19.8°
b = 10.823 (4) ŵ = 0.32 mm1
c = 11.123 (4) ÅT = 293 K
β = 98.27 (2)°Prism, pale brown
V = 1234.2 (7) Å30.40 × 0.10 × 0.08 mm
Z = 4
Data collection top
Bruker–Nonius KappaCCD
1405 independent reflections
Radiation source: normal-focus sealed tube999 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.048
Detector resolution: 9 pixels mm-1θmax = 27.5°, θmin = 3.1°
CCD rotation images, thick slices scansh = 1213
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
k = 1412
Tmin = 0.884, Tmax = 0.977l = 1414
4820 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.047Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.128H atoms treated by a mixture of independent and constrained refinement
S = 1.05 w = 1/[σ2(Fo2) + (0.057P)2 + 1.1655P]
where P = (Fo2 + 2Fc2)/3
1405 reflections(Δ/σ)max < 0.001
102 parametersΔρmax = 0.28 e Å3
0 restraintsΔρmin = 0.37 e Å3
Crystal data top
C8H13N10+·ClV = 1234.2 (7) Å3
Mr = 284.73Z = 4
Monoclinic, C2/cMo Kα radiation
a = 10.360 (3) ŵ = 0.32 mm1
b = 10.823 (4) ÅT = 293 K
c = 11.123 (4) Å0.40 × 0.10 × 0.08 mm
β = 98.27 (2)°
Data collection top
Bruker–Nonius KappaCCD
1405 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
999 reflections with I > 2σ(I)
Tmin = 0.884, Tmax = 0.977Rint = 0.048
4820 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0470 restraints
wR(F2) = 0.128H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 0.28 e Å3
1405 reflectionsΔρmin = 0.37 e Å3
102 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
C10.41283 (19)0.7142 (2)0.5276 (2)0.0278 (5)
C20.3433 (2)0.5222 (2)0.51757 (19)0.0276 (5)
C30.2841 (2)0.4103 (2)0.4657 (2)0.0323 (5)
C40.2814 (2)0.3050 (2)0.5256 (2)0.0307 (5)
N10.38783 (18)0.54308 (17)0.63082 (16)0.0313 (5)
N20.43126 (19)0.66519 (17)0.63755 (18)0.0317 (5)
H20.473 (5)0.691 (5)0.699 (4)0.038*0.50
N30.35804 (16)0.62667 (16)0.45004 (16)0.0267 (4)
N40.3270 (2)0.6457 (2)0.32470 (18)0.0372 (5)
H4A0.248 (3)0.630 (3)0.304 (3)0.045*
H4B0.370 (3)0.585 (3)0.292 (3)0.045*
N50.4393 (2)0.82900 (19)0.4965 (2)0.0365 (5)
H5A0.428 (3)0.849 (3)0.420 (3)0.044*
H5B0.477 (3)0.884 (3)0.558 (3)0.044*
Cl10.50000.98424 (10)0.75000.0552 (3)
Atomic displacement parameters (Å2) top
C10.0261 (10)0.0267 (12)0.0304 (11)0.0013 (8)0.0038 (8)0.0021 (9)
C20.0283 (10)0.0270 (12)0.0273 (11)0.0004 (8)0.0031 (8)0.0020 (9)
C30.0352 (11)0.0319 (13)0.0282 (11)0.0011 (9)0.0003 (9)0.0045 (10)
C40.0351 (11)0.0286 (12)0.0279 (11)0.0017 (9)0.0027 (8)0.0044 (9)
N10.0376 (10)0.0278 (10)0.0274 (10)0.0046 (8)0.0008 (8)0.0008 (8)
N20.0393 (10)0.0249 (10)0.0291 (10)0.0053 (8)0.0009 (8)0.0011 (8)
N30.0312 (9)0.0259 (10)0.0225 (9)0.0021 (7)0.0019 (7)0.0002 (7)
N40.0486 (12)0.0399 (12)0.0226 (10)0.0037 (10)0.0031 (8)0.0003 (9)
N50.0492 (12)0.0249 (11)0.0350 (11)0.0049 (8)0.0046 (9)0.0020 (9)
Cl10.0648 (6)0.0474 (6)0.0497 (6)0.0000.0042 (5)0.000
Geometric parameters (Å, º) top
C1—N21.321 (3)C4—H40.9300
C1—N51.329 (3)N1—N21.395 (3)
C1—N31.350 (3)N2—H20.80 (5)
C2—N11.298 (3)N3—N41.400 (3)
C2—N31.378 (3)N4—H4A0.84 (3)
C2—C31.440 (3)N4—H4B0.90 (3)
C3—C41.322 (3)N5—H5A0.87 (3)
C3—H30.9300N5—H5B0.95 (3)
C4—C4i1.434 (4)
N2—C1—N5127.5 (2)C1—N2—N1109.15 (18)
N2—C1—N3107.5 (2)C1—N2—H2129 (4)
N5—C1—N3124.9 (2)N1—N2—H2121 (4)
N1—C2—N3109.54 (19)C1—N3—C2107.25 (18)
N1—C2—C3127.4 (2)C1—N3—N4123.27 (19)
N3—C2—C3123.1 (2)C2—N3—N4129.47 (19)
C4—C3—C2124.2 (2)N3—N4—H4A109 (2)
C4—C3—H3117.9N3—N4—H4B104.1 (18)
C2—C3—H3117.9H4A—N4—H4B105 (3)
C3—C4—C4i123.8 (3)C1—N5—H5A118.8 (19)
C3—C4—H4118.1C1—N5—H5B118.1 (17)
C4i—C4—H4118.1H5A—N5—H5B123 (3)
C2—N1—N2106.51 (18)
N1—C2—C3—C49.0 (4)N2—C1—N3—C20.3 (2)
N3—C2—C3—C4172.4 (2)N5—C1—N3—C2178.3 (2)
C2—C3—C4—C4i177.9 (3)N2—C1—N3—N4178.77 (19)
N3—C2—N1—N20.8 (2)N5—C1—N3—N42.7 (3)
C3—C2—N1—N2177.9 (2)N1—C2—N3—C10.7 (2)
N5—C1—N2—N1178.7 (2)C3—C2—N3—C1178.1 (2)
N3—C1—N2—N10.2 (2)N1—C2—N3—N4178.3 (2)
C2—N1—N2—C10.6 (2)C3—C2—N3—N43.0 (3)
Symmetry code: (i) x+1/2, y+1/2, z+1.
Hydrogen-bond geometry (Å, º) top
N2—H2···N2ii0.80 (5)1.97 (5)2.695 (4)151 (5)
N4—H4B···N1iii0.90 (3)2.29 (3)3.100 (3)149 (2)
N4—H4A···Cl1iv0.84 (3)2.83 (3)3.652 (3)165 (3)
N5—H5A···Cl1v0.87 (3)2.79 (3)3.534 (2)144 (2)
N5—H5B···Cl10.95 (3)2.37 (3)3.265 (2)156 (2)
Symmetry codes: (ii) x+1, y, z+3/2; (iii) x, y+1, z1/2; (iv) x+1/2, y+3/2, z+1; (v) x+1, y+2, z+1.

Experimental details

Crystal data
Chemical formulaC8H13N10+·Cl
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)10.360 (3), 10.823 (4), 11.123 (4)
β (°) 98.27 (2)
V3)1234.2 (7)
Radiation typeMo Kα
µ (mm1)0.32
Crystal size (mm)0.40 × 0.10 × 0.08
Data collection
DiffractometerBruker–Nonius KappaCCD
Absorption correctionMulti-scan
(SADABS; Bruker, 2001)
Tmin, Tmax0.884, 0.977
No. of measured, independent and
observed [I > 2σ(I)] reflections
4820, 1405, 999
(sin θ/λ)max1)0.650
R[F2 > 2σ(F2)], wR(F2), S 0.047, 0.128, 1.05
No. of reflections1405
No. of parameters102
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.28, 0.37

Computer programs: COLLECT (Nonius, 1999), DIRAX/LSQ (Duisenberg et al., 2000), EVALCCD (Duisenberg et al., 2003), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006), WinGX (Farrugia, 2012).

Hydrogen-bond geometry (Å, º) top
N2—H2···N2i0.80 (5)1.97 (5)2.695 (4)151 (5)
N4—H4B···N1ii0.90 (3)2.29 (3)3.100 (3)149 (2)
N4—H4A···Cl1iii0.84 (3)2.83 (3)3.652 (3)165 (3)
N5—H5A···Cl1iv0.87 (3)2.79 (3)3.534 (2)144 (2)
N5—H5B···Cl10.95 (3)2.37 (3)3.265 (2)156 (2)
Symmetry codes: (i) x+1, y, z+3/2; (ii) x, y+1, z1/2; (iii) x+1/2, y+3/2, z+1; (iv) x+1, y+2, z+1.
Acknowledgements top

The authors thank the Centro Interdipartimentale di Metodologie Chimico–Fisiche, Università degli Studi di Napoli "Federico II".