N,N′-Bis(2-amino­benz­yl)ethane-1,2-diaminium dinitrate

Luis Ángel Garza Rodríguez; Perla Elizondo Martínez; Sylvain Bernès; Blanca Nájera Martínez; Nancy Pérez Rodríguez

doi:10.1107/S1600536813027475

. 2013 Oct 16;69(Pt 11):o1643–o1644. doi: 10.1107/S1600536813027475

N,N′-Bis(2-aminobenzyl)ethane-1,2-diaminium dinitrate

Luis Ángel Garza Rodríguez ^a, Perla Elizondo Martínez ^b, Sylvain Bernès ^b,^*, Blanca Nájera Martínez ^b, Nancy Pérez Rodríguez ^b

PMCID: PMC3884311 PMID: 24454087

Abstract

In the title salt, C₁₆H₂₄N₄ ²⁺·2NO₃ ⁻, both the cation and anion are placed in general positions, although the cation displays non-crystallographic inversion symmetry, with the aliphatic chain extended in an all-trans conformation. The benzene rings are almost parallel, with a dihedral angle between their mean planes of 3.3 (6)°. The nitrate ions are placed in the vicinity of the protonated amine groups, forming efficient N—H⋯O inter-ion hydrogen bonds. Each nitrate ion in the asymmetric unit bridges two symmetry-related cations, forming an R ₄ ⁴(18) ring, a common motif in organic ammonium nitrate salts. This results in the formation of chains along [010] with alternating cations and anions. The neutral amine groups are involved in slightly weaker N—H⋯O hydrogen bonds with the nitrate O atoms, and there are also a number of C—H⋯O hydrogen bonds present. The resulting supramolecular structure is based on a two-dimensional network extending in the ab plane.

Related literature

For the structure of the free neutral amine, see: Rodríguez de Barbarín et al. (2007 ▶). For the p-toluenesulfonate salt of the title cation, see: Garza Rodríguez et al. (2011 ▶). For related diammonium nitrate salts featuring Inline graphic (18) motifs, see: Liu et al. (2007 ▶); Yang et al. (2007 ▶). For supramolecular motifs nomenclature, see: Etter (1990 ▶). For the synthesis of the title salt, see: Garza Rodríguez (2010 ▶). graphic file with name e-69-o1643-scheme1.jpg

Experimental

Crystal data

C₁₆H₂₄N₄ ²⁺·2NO₃ ⁻
M _r = 396.41
Orthorhombic,
a = 11.041 (5) Å
b = 5.760 (4) Å
c = 30.069 (13) Å
V = 1912.1 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 298 K
0.60 × 0.20 × 0.20 mm

Data collection

Siemens P4 diffractometer
4371 measured reflections
2473 independent reflections
1501 reflections with I > 2σ(I)
R _int = 0.053
3 standard reflections every 97 reflections intensity decay: 1.5%

Refinement

R[F ² > 2σ(F ²)] = 0.061
wR(F ²) = 0.180
S = 1.61
2473 reflections
278 parameters
13 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Data collection: XSCANS (Siemens, 1996 ▶); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS2013 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXL2013.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813027475/rk2415sup1.cif

e-69-o1643-sup1.cif^{(171.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813027475/rk2415Isup2.hkl

e-69-o1643-Isup2.hkl^{(136KB, hkl)}

Click here for additional data file.^{(7.5KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536813027475/rk2415Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N9—H9A⋯O23ⁱ	0.94 (4)	1.87 (3)	2.794 (8)	167 (7)
N9—H9B⋯O24	0.95 (5)	1.96 (5)	2.879 (7)	164 (5)
N12—H12A⋯O27	0.92 (3)	1.88 (3)	2.787 (8)	168 (8)
N12—H12B⋯O28ⁱ	0.91 (5)	1.95 (5)	2.862 (8)	176 (9)
N1—H1B⋯O22ⁱⁱ	0.90 (7)	2.55 (8)	3.290 (11)	141 (9)
N1—H1B⋯O24ⁱⁱ	0.90 (7)	2.40 (7)	3.272 (10)	166 (9)
N9—H9A⋯O22ⁱ	0.94 (4)	2.38 (6)	3.050 (8)	128 (5)
N12—H12A⋯O26	0.92 (3)	2.36 (5)	3.046 (8)	132 (4)
N12—H12B⋯O27ⁱ	0.91 (5)	2.49 (5)	3.096 (8)	125 (4)
N20—H20B⋯O26ⁱⁱⁱ	0.91 (7)	2.56 (8)	3.246 (12)	133 (8)
N20—H20B⋯O28ⁱⁱⁱ	0.91 (7)	2.32 (8)	3.204 (11)	165 (8)
C8—H8B⋯O24ⁱⁱ	0.97	2.46	3.327 (9)	149
C10—H10A⋯O24ⁱⁱ	0.97	2.41	3.258 (8)	145
C10—H10B⋯O22^iv	0.97	2.58	3.291 (9)	130
C11—H11A⋯O27ⁱ	0.97	2.56	3.147 (9)	119
C11—H11A⋯O26^v	0.97	2.57	3.285 (9)	131
C11—H11B⋯O28ⁱⁱⁱ	0.97	2.41	3.249 (9)	145
C13—H13A⋯O28ⁱⁱⁱ	0.97	2.46	3.315 (10)	147

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

The authors thank the FCQ–UANL (project No. 03-6375-QMT-08-005) and PAICyT (Project No. IT164-09) for financial support. LAGR acknowledges a grant from the CONACyT program "Dirección de Tesis entre la UANL y la University of Texas at Austin y/o Instituciones de Educación Superior de la ANUIES" (grant N.L.-2006-C09 32658).

supplementary crystallographic information

1. Comment

The title salt crystallized unexpectedly, when attempting the crystallization of a macrocyclic molecule, resulting from the Schiff condensation between 2,6-diacetylpyridine and N,N'-bis(2-aminobenzyl)ethane-1,2-diamine (Garza Rodríguez, 2010). The synthesis was carried out via a template reaction, using Mn²⁺ as metal center, and analytical data showed that the Mn²⁺ complex was formed, with nitrate as counter ions. However, this compound is almost insoluble in organic solvents, like MeOH, EtOH, acetone and ethyl acetate, impeding the preparation of single crystals. Only slight solubility was obtained in hot acetonitrile. Slow evaporation of MeCN over 3 weeks afforded a mixture of amorphous brown solids and colourless needle-shaped crystals. We assume that the brown solids should be a mixture of manganese oxides, resulting from the hydrolysis of the complex induced by trace amounts of water and dissolved O₂. Minutes amounts of H₃O⁺ are then released, which promote the formation, and finally the crystallization of the nitrate salt of the protonated amine.

Title compound (Fig. 1) crystallizes in a non-centrosymmetric space group, with all atoms placed in general positions. However, the dication (C₁₆H₂₄N₄)²⁺ presents a non-crystallographic inversion center, with the central aliphatic chain extended in the all-trans conformation. This conformation was previously obtained for the same cation crystallized as p-toluenesulfonate salt, although in that case, the dication was placed on a crystallographic inversion center (Garza Rodríguez et al., 2011). The free amine, for which the X-ray structure is also known (Rodríguez de Barbarín et al., 2007) has a different solid state conformation, although preserving the centrosymmetric character. For the nitrate salt reported here, departure from centrosymmetry is small, as reflected, for example, by the dihedral angle between benzene rings, limited to 3.3 (6)°.

Nitrate ions positions are determined by the formation of hydrogen bonds with ammonium NH₂⁺ groups in the cation. All N—H···O angles for these contacts are close to 180°, and H···O separations are in the range 1.87 (3)Å to 1.96 (3)Å. Each independent anion, N21 and N25, bridges two cations related by cell translation in the [0 1 0] direction, forming a R₄⁴(18) ring motif (Etter, 1990; Fig. 2). This arrangement seems actually to be common in crystal structures involving ammonium and nitrate species, and R₄⁴(18) motifs are also formed in salts closely related to the title compound, for example with N,N'-dibenzylethane-1,2-diammonium (Liu et al., 2007) or N,N'-bis(4-chlorobenzyl)ethane-1,2-diammonium (Yang et al., 2007). For such salts, the crystal structure is invariably based on edge-fused R₄⁴(18) rings, which afford a one-dimensional linear supramolecular structure. In the case of the title compound, chains run along the short b axis, and no significant interchain interactions are observed (Fig. 2).

2. Experimental

An amount of 2,6-diacetylpyridine (735 mg, 4.50 mmol) in ethanol (180 ml) was mixed with the templating reagent Mn(NO₃)₂·xH₂O (1.130 g) and refluxed for 30 min. Then, N,N'-bis(2-aminobenzyl)ethane-1,2-diamine (1.302 g, 4.80 mmol, dissolved in 25 ml of ethanol) was slowly added, and the mixture further refluxed for 1 h. The resulting solid was filtered from hot ethanol, washed with cold ethanol, and dried under reduced pressure. A solution of the solid in hot CH₃CN was left to crystallize for 3 weeks. After this time, only one product was obtained as single crystals, in low yield, which was identified by X-ray diffraction as the title nitrate salt.