2-Amino-5-bromo­pyridin-1-ium (2-amino-5-bromo­pyridine-κN 1)trichloridozincate

Fitriani; Kanidtha Hansongnern; Nararak Leesakul; Chaveng Pakawatchai; Saowanit Saithong

doi:10.1107/S1600536813011884

. 2013 May 4;69(Pt 6):m302. doi: 10.1107/S1600536813011884

2-Amino-5-bromopyridin-1-ium (2-amino-5-bromopyridine-κN ¹)trichloridozincate

Fitriani ^a, Kanidtha Hansongnern ^a,^*, Nararak Leesakul ^a, Chaveng Pakawatchai ^a, Saowanit Saithong ^a

PMCID: PMC3684871 PMID: 23794973

Abstract

The structure of the title salt, (C₅H₆BrN₂)[ZnCl₃(C₅H₅BrN₂)], consists of discrete 2-amino-5-bromopyridin-1-ium cations and distorted tetrahedral (2-amino-5-bromopyridine)trichloridozincate anions. In the crystal, the complex anions and cations are linked via N—H⋯Cl hydrogen bonds into layers parallel to (101). Short Br⋯Cl contacts of 3.4239 (11) and 3.4503 (12) Å are observed, as well as π–π stacking interactions between the pyridine and pyridinium rings, with alternating centroid-to-centroid distances of 3.653 (2) and 3.845 (2) Å.

Related literature

For background to the chemistry of substituted pyridines, see: Janiak et al. (1999 ▶); Hubrich et al. (2010 ▶); Wei et al. (2012 ▶). For the biological activities and electrochemical properties of pyridine derivatives, see: Jo et al. (2004 ▶); Xiao et al. (2012 ▶). graphic file with name e-69-0m302-scheme1.jpg

Experimental

Crystal data

(C₅H₆BrN₂)[ZnCl₃(C₅H₅BrN₂)]
M _r = 518.77
Monoclinic,
a = 9.4238 (4) Å
b = 13.6544 (6) Å
c = 13.5679 (6) Å
β = 104.349 (1)°
V = 1691.40 (13) Å³
Z = 4
Mo Kα radiation
μ = 6.64 mm⁻¹
T = 293 K
0.26 × 0.16 × 0.08 mm

Data collection

Bruker APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2003 ▶) T _min = 0.286, T _max = 0.576
18043 measured reflections
2979 independent reflections
2491 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.086
S = 1.02
2979 reflections
196 parameters
5 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.23 e Å⁻³
Δρ_min = −0.40 e Å⁻³

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶), PLATON (Spek, 2009 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Click here for additional data file.^{(22.5KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813011884/wm2739sup1.cif

e-69-0m302-sup1.cif^{(22.5KB, cif)}

Click here for additional data file.^{(146.2KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813011884/wm2739Isup2.hkl

e-69-0m302-Isup2.hkl^{(146.2KB, 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
N2—H2A⋯Cl1	0.87 (2)	2.50 (3)	3.315 (4)	156 (4)
N2—H2B⋯Cl2ⁱ	0.87 (2)	2.43 (2)	3.288 (4)	169 (5)
N3—H3A⋯Cl1ⁱⁱ	0.87 (2)	2.75 (4)	3.309 (4)	124 (3)
N3—H3A⋯Cl1ⁱⁱⁱ	0.87 (2)	2.74 (4)	3.297 (4)	123 (4)
N4—H4A⋯Cl3ⁱⁱⁱ	0.88 (2)	2.49 (3)	3.328 (4)	159 (4)
N4—H4B⋯Cl2^iv	0.87 (2)	2.46 (3)	3.295 (4)	160 (4)

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

Acknowledgments

The authors express their gratitute to the Center for Innovation in Chemistry (PERCH–CIC) and the Graduate School, Prince of Songkla University, Thailand, for financial support. One of the authors (Fitriani) is grateful to the Directorate General of Higher Education (DGHE) of Indonesia and Brawijaya University, Indonesia, for financial assistance and a DGHE postgraduate scholarship.

supplementary crystallographic information

Comment

In recent years, pyridine and its derivatives were found to be suitable ligands for transition metal coordination compounds involving Fe^II, Ni^II (Janiak et al., 1999); Cu^II, Co^II (Hubrich et al., 2010) and Zn^II (Wei et al., 2012). Several pyridine derivatives play important roles in biological activities (Jo et al., 2004) or have interesting electrochemical properties (Xiao et al., 2012).

In the present work, 2-amino-5-bromopyridine was reacted with ZnCl₂ in acidic solution, forming the pyridinium cation, [C₅H₆BrN₂]⁺, accompanied by the complex anion, [ZnCl₃(C₅H₅BrN₂]^- (Fig. 1). In the anion, the Zn^II atom is in a distorted tetrahedral coordination geometry, bonded to the N atom of the pyridine ring of neutral 2-amino-5-bromopyridine and to three Cl atoms. The amino group is not involved in metal coordination. The Zn1—N1 bond length is 2.052 (3) Å, and the three Zn—Cl bond lengths are Zn1—Cl1 = 2.2494 (11) Å; Zn1—Cl2 = 2.2691 (11) Å; Zn1—Cl3 = 2.2499 (11) Å. The angles around the Zn^II atom range from 104.99 (9) to 114.22 (4)°, indicating a slight deviation from the the ideal tetrahedral angles.

Both intra- and inter-molecular N—H···Cl hydrogen-bonding interactions are observed (Fig. 2). The only intramolecular hydrogen bond is in the complex anion, namely between the N2 atom of the amino group and the Cl1 atom [N2—H2A···Cl1, N2···Cl1 = 3.315 (4) Å]. The N2 donor is also connected to the Cl2ⁱ atom (i: -x + 3/2, y + 1/2, -z + 1/2) of an adjacent anionic complex as an inter-molecular interaction [N2—H2B···Cl2ⁱ, N2···Cl2ⁱ = 3.288 (4) Å]. Other inter-molecular hydrogen bonds are found between the N-amino group of the cation and Cl atoms of different anionic complexes [N4—H4A···Cl3ⁱⁱⁱ, N4···Cl3ⁱⁱⁱ = 3.328 (4) Å; iii: -x + 1, -y, -z + 1; N4—H4B···Cl2^iv, N4···Cl2^iv = 3.295 (4) Å; iv: x - 1/2, -y + 1/2, z + 1/2]. In addition, inter-molecular hydrogen bonding of the type N—H···Cl is also found among the protonated N atom of the cation and other two Cl atoms of two nearby anionic complexes [N3—H3A···Cl1ⁱⁱ, N3···Cl1ⁱⁱ = 3.309 (4) Å; ii: x - 1, y, z; N3—H3A···Cl1ⁱⁱⁱ, N3···Cl1ⁱⁱⁱ = 3.297 (4) Å]. All these inter-molecular hydrogen-bonding interactions generate a layer-like arrangement parallel to (101).

A short halogen···halogen contact of the type Br···Cl is found between the Br1 atom of the 2-amino-5-bromopyridine ligand of the complex anion and the Cl2 atom of an adjacent complex anion [Br1···Cl2 = 3.4239 (11) Å]. Furthermore, the Br2 atom of the neighbouring 2-amino-5-bromopyridinium cation also has a short contact to this Cl2 atom with a Br2···Cl2 distance of 3.4503 (12) Å as depicted in Fig. 3.

The crystal packing is futher stabilized by π–π stacking interactions between the pyridine ring (Cg1) of the anionic complex and the pyridinium ring (Cg2) with alternating centroid···centroid distances of Cg2···Cg1 = 3.653 (2) Å and Cg1···Cg2 = 3.845 (2) Å (Fig. 4). These interactions generate π–π stacking chains parallel to [101]. All in all, the stability of the crystal packing is governed by various interactions, including N—H···Cl hydrogen bonds, Br···Cl short contacts and π–π stacking, respectively.

Experimental

The title compound was synthesized by dissolving zinc chloride (480 mg, 3 mmol) in methanol (10 ml) which was added to a methanolic solution of 2-amino-5-bromopyridine (519 mg, 3 mmol). The reaction mixture was stirred in the presence of a few drops of concentrated hydrochloric acid. The final pH of the solution was adjusted to 3. After stirring for 5 h, the resulting solution was filtered off and the filtrate was left for slow evaporation of the solvent at ambient temperature. After several days, brown crystals suitable for X-ray diffraction analysis were collected by filtration, washed several times with methanol and dried in a desiccator over silica gel.

The analytical data of the zinc(II) complex are given as follows. [C₅H₆BrN₂]⁺.[ZnCl₃(C₅H₅BrN₂)]^-. Yield 0.42 g, 27%. m.p. 461–463 K. Anal. Calcd. for [C₅H₆BrN₂]⁺.[ZnCl₃(C₅H₅BrN₂)]^-: C 23.15, H 2.14, N 10.80%. Found: C 23.31, H 2.09, N 10.64%.