Bis(2-amino-3-nitro­pyridinium) dichromate(VI)

Samah Akriche; Mohamed Rzaigui

doi:10.1107/S1600536808043018

. 2008 Dec 20;65(Pt 1):m123. doi: 10.1107/S1600536808043018

Bis(2-amino-3-nitropyridinium) dichromate(VI)

Samah Akriche ^a,^*, Mohamed Rzaigui ^a

PMCID: PMC2968023 PMID: 21581487

Abstract

The title compound, (C₅H₆N₃O₂)₂[Cr₂O₇], consists of 2-amino-3-nitropyridinium cations and discrete dichromate anions linked together by N—H⋯O and C—H⋯O hydrogen bonds, forming thick layers parallel to (101). Layer cohesion is ensured by N—H⋯O hydrogen bonding in addition to electrostatic and van der Waals interactions, forming a three-dimensional framework. The dichromate anion is located on a twofold axis that passes through its bridging O atom.

Related literature

For related structures, see: Akriche & Rzaigui (2000 ▶); Khadhrani et al. (2006 ▶); Nicoud et al. (1997 ▶); Panunto et al. (1987 ▶); Sieroń (2007 ▶); Le Fur et al. (1998 ▶). For a discussion of hydrogen bonding, see: Desiraju (1989 ▶, 1995 ▶).

Experimental

Crystal data

(C₅H₆N₃O₂)₂[Cr₂O₇]
M _r = 496.26
Monoclinic,
a = 14.799 (2) Å
b = 7.464 (3) Å
c = 17.870 (5) Å
β = 116.71 (4)°
V = 1763.3 (11) Å³
Z = 4
Mo Kα radiation
μ = 1.31 mm⁻¹
T = 298 K
0.25 × 0.23 × 0.19 mm

Data collection

Enraf–Nonius TurboCAD-4 diffractometer
Absorption correction: none
3444 measured reflections
2123 independent reflections
1562 reflections with I > 2σ(I)
R _int = 0.021
2 standard reflections frequency: 120 min intensity decay: 3%

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.106
S = 1.04
2123 reflections
132 parameters
H-atom parameters constrained
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.37 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1996 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-32 for Windows (Farrugia, 1998 ▶); DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808043018/dn2417sup1.cif

e-65-0m123-sup1.cif^{(14.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808043018/dn2417Isup2.hkl

e-65-0m123-Isup2.hkl^{(102.3KB, hkl)}

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
N1—H1⋯O2	0.86	1.87	2.707 (3)	165
N2—H2A⋯O4	0.86	2.17	2.974 (4)	155
N2—H2B⋯O6	0.86	2.06	2.654 (4)	125
N2—H2B⋯O6ⁱ	0.86	2.59	3.061 (4)	116
C3—H3⋯O4ⁱⁱ	0.93	2.58	3.494 (4)	167
C4—H4⋯O3ⁱⁱⁱ	0.93	2.50	3.337 (4)	150
C5—H5⋯O2^iv	0.93	2.34	3.232 (4)	160

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

supplementary crystallographic information

Comment

A new engineering strategy using organic-inorganic hybrid materials have appeared over the past years. The challenge was to combine the advantages of organic crystals and those of the inorganic materials. As a part of our study of crystal packing in amino-nitro "push-pull" system, a new organic-inorganic salt, bis (2-amino-3-nitropyridinium) dichromate (I) have been synthesized.

The dichromate anion has a binary internal symmetry since its bridging oxygen atom is located on a twofold axis, and so is built by only one independent (CrO₄) group. This later with one independent (2-NH₂-3-NO₂C₅H₃NH)₊ cation constitute the asymmetric unit of (I) (Fig. 1).

As expected, the main geometrical features of anion agree with those previously observed for this group in other coumpounds (Sieroń, 2007; Khadhrani et al.,2006). The bond lengths and the angles within the cation are comparable with those observed for 2-amino-3-nitropyridinium dihydrogenphosphate (Akriche et al.,2000), 2-amino-3-nitropyridinium hydrogensulfate(Le Fur et al., 1998) and 2-amino-3-nitropyridinium chloride (Nicoud et al.,1997).

The dichromate and organic entities manifest different interactions (electrostatic, H-bonds, Van Der Waals) to keep up the three-dimensionel network cohesion (Fig. 2). The main links are from the N—H···O bonds (Table 1) with H···O bond lengths falling in the range from 1.87–2.59 Å.

Long C—H···O contacts occur between cations and cation-anion moities with C···O bond lengths ranging from 3.494 (4)–3.232 (4)Å (Desiraju, 1989; Desiraju, 1995).

It's worth noticing the intracation contact N2—H2B···O6 (see Table 1 for symmetry code) which is always present in nitroaniline in which nitro and amino groups are ortho to one another, as clearly shown in a study of hydrogen patterns of nitroaniline derivatives (Panunto et al., 1987). This situation precludes the rotation of the nitro group with respect to pyridinium ring. The angle between the planes of the NO₂group and the heterocycle is 7.98° for cation, indicating a coplanar geometry.

Experimental

0.004 mol of 2-amino-3-nitropyridine was dissolved in 20 ml of pure acetic acid. 5 ml solution containing 0.004 mol of CrO₃ was added drop by drop under stirring at 333 K. The obtained solution is slowly evaporated at the ambiant temperature. After some days, Brown single crystals of the title compound are formed in the reactionnel midle.