3,4-Diaminopyridinium 2-carboxy-4,6-dinitrophenolate

Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536810038936

. 2010 Oct 9;66(Pt 11):o2747. doi: 10.1107/S1600536810038936

3,4-Diaminopyridinium 2-carboxy-4,6-dinitrophenolate

Madhukar Hemamalini ^a, Hoong-Kun Fun ^a,^*,^‡

PMCID: PMC3009103 PMID: 21588952

Abstract

In the title salt, C₅H₈N₃ ⁺·C₇H₃N₂O₇ ⁻, the pyridine N atom of the 3,4-diaminopyridine molecule is protonated. The 3,5-dinitrosalicylate anion shows whole-molecule disorder over two orientations with a refined occupancy ratio of 0.875 (4): 0.125 (4). In the crystal, the cations and anions are connected by intermolecular N—H⋯O and C—H⋯O hydrogen bonds, forming a three-dimensional network.

Related literature

For applications of diaminopyridine, see: Abu Zuhri & Cox (1989 ▶); Inuzuka & Fujimoto (1990 ▶); El-Mossalamy (2001 ▶). For related structures, see: Rubin-Preminger & Englert (2007 ▶); Koleva et al. (2007 ▶); Koleva et al. (2008 ▶). For reference bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₅H₈N₃ ⁺·C₇H₃N₂O₇ ⁻
M _r = 337.26
Monoclinic,
a = 9.1187 (4) Å
b = 11.3569 (5) Å
c = 13.1343 (6) Å
β = 98.204 (4)°
V = 1346.27 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.14 mm⁻¹
T = 100 K
0.52 × 0.11 × 0.10 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.931, T _max = 0.986
10195 measured reflections
2785 independent reflections
1979 reflections with I > 2σ(I)
R _int = 0.064

Refinement

R[F ² > 2σ(F ²)] = 0.070
wR(F ²) = 0.162
S = 1.12
2785 reflections
287 parameters
526 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.46 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810038936/hb5660sup1.cif

e-66-o2747-sup1.cif^{(22.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810038936/hb5660Isup2.hkl

e-66-o2747-Isup2.hkl^{(134KB, 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—H1N1⋯O1	1.07	1.76	2.753 (4)	153
N2—H2N2⋯O6ⁱ	0.89	2.24	3.120 (4)	171
N2—H1N2⋯O3ⁱⁱ	1.03	2.11	3.026 (5)	146
N3—H1N3⋯O6ⁱ	0.89	2.36	3.104 (4)	142
N3—H2N3⋯O5ⁱⁱⁱ	1.00	2.24	3.217 (5)	163
C6—H6A⋯O3^iv	0.93	2.56	3.299 (6)	136

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

Acknowledgments

MH and HKF thank the Malaysian Government and Universiti Sains Malaysia for the Research University grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Diaminopyridine have an important role in the preparation of aromatic azo dyes (Abu Zuhri & Cox, 1989; Inuzuka & Fujimoto, 1990) and in many polarographic investigations (El-Mossalamy, 2001). The crystal structure of 3,4-diaminopyridine (Rubin-Preminger & Englert, 2007), 3,4-diaminopyridinium hydrogen squarate (Koleva et al., 2007) and 3,4-diaminopyridinium hydrogen tartarate (Koleva et al., 2008) have been reported in the literature. 3,5-Dinitrosalicylic acid (DNSA) has proved to be effective as a proton-donating acid species for stabilizing crystalline salts of Lewis bases. Since our aim is to study some interesting hydrogen-bonding interactions, the synthesis and structure of the title compound (I) is presented here.

The asymmetric unit of (I) (Fig 1), contains a protonated 3,4-diaminopyridinium cation and a 3,5-dinitrosalicylate anion. The bond lengths (Allen et al., 1987) and angles are normal. In the 3,4-diaminopyridinium cation (the proton transfer from the hydroxyl group of the anion), protonation of the N1 atom leads to a slight increase in the C1—N1—C5 angle to 122.1 (3)°, compared to 115.69 (19)° in 3,4-diaminopyridine (Rubin-Preminger & Englert, 2007). The whole 3,5-dinitrosalicylate anion is disordered over two positions with a refined occupancy ratio of 0.886 (4): 0.114 (4). Excluding amino group, the pyridine is planar, with a maximum deviation of 0.010 (3) Å for atom C2.

In the crystal structure (Fig. 2), there is an intramolecular O2—H2···O1 hydrogen bond in the 3,5-dinitrosalicylate anion, which generates an S(6) (Bernstein et al., 1995) ring motif. Furthermore, the cations and anions are connected by intermolecular strong N1—H1N1···O1; N2—H2N2···O6; N2—H1N2···O3; N3—H1N3···O6; N3—H2N3···O5 and weak C6—H6A···O3 hydrogen bonds, forming a three-dimensional network.

Experimental

A hot methanol solution (20 ml) of 3,4-diaminopyridine (27 mg, Aldrich) and 3,5-dinitrosalicylic acid (57 mg, Merck) were mixed and warmed over a heating magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound appeared after a few days.