2-(2-Pyridylamino)pyridinium tetra­chlorido­zincate(II)

Diego Venegas-Yazigi; Carolina Castillo; Verónica Paredes-García; Andrés Vega; Evgenia Spodine

doi:10.1107/S1600536808007745

. 2008 May 7;64(Pt 6):m777–m778. doi: 10.1107/S1600536808007745

2-(2-Pyridylamino)pyridinium tetrachloridozincate(II)

Diego Venegas-Yazigi ^a,^b,^*, Carolina Castillo ^c, Verónica Paredes-García ^c,^b, Andrés Vega ^d, Evgenia Spodine ^e,^b

PMCID: PMC2961562 PMID: 21202468

Abstract

The structure of the title compound, (C₁₀H₁₀N₃)₂[ZnCl₄], is composed of C₁₀H₉N₃H⁺ (DPAH⁺) cations and [ZnCl₄]²⁻ anions. The two pyridyl rings of DPAH⁺ are approximately coplanar, with a dihedral angle of 7.2 (2)° between their corresponding least-squares planes. The proton is disordered in a one-to-one ratio over the two chemically equivalent pyridyl N atoms. An intramolecular hydrogen bond is formed between the pyridinium H atom and the pyridyl N atom of the other pyridyl ring. The Zn atom lies on a twofold rotation axis. There are also some weak N—H⋯Cl hydrogen bonds. These interactions lead to the formation of an alternating zigzag chain in the solid state. The results clearly show that reducing agents normally used in hydrothermal syntheses, such as metallic zinc employed here, are also active in terms of coordination chemistry.

Related literature

For related literature, see: Bock et al. (1998 ▶); Bose et al. (2004 ▶); Camus et al. (2000 ▶); Chowdhury et al. (2005 ▶); Du & Zhao (2004 ▶); Gillon et al. (2000 ▶); Marinescu et al. (2005 ▶); Rahaman et al. (2005 ▶); Rice et al. (2002 ▶); Visser et al. (1997 ▶); Willett (1995 ▶); Youngme et al. (2005 ▶).

Experimental

Crystal data

(C₁₀H₁₀N₃)₂[ZnCl₄]
M _r = 551.61
Monoclinic,
a = 14.620 (3) Å
b = 11.260 (2) Å
c = 14.765 (3) Å
β = 101.13 (3)°
V = 2384.9 (8) Å³
Z = 4
Mo Kα radiation
μ = 1.50 mm⁻¹
T = 150 (2) K
0.1 × 0.1 × 0.1 mm

Data collection

Siemens SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS in SAINT-NT; Bruker, 1999 ▶) T _min = 0.861, T _max = 0.861
8907 measured reflections
2718 independent reflections
2063 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.079
S = 1.17
2718 reflections
145 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.53 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Data collection: SMART-NT (Bruker, 2001 ▶); cell refinement: SAINT-NT (Bruker, 1999 ▶); data reduction: SAINT-NT; program(s) used to solve structure: SHELXTL-NT (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL-NT; molecular graphics: SHELXTL-NT; software used to prepare material for publication: SHELXTL-NT.

Supplementary Material

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S1600536808007745/zl2105sup1.cif

e-64-0m777-sup1.cif^{(17.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808007745/zl2105Isup2.hkl

e-64-0m777-Isup2.hkl^{(133.6KB, 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—H1N⋯N3	1.06	1.82	2.612 (3)	129
N3—H3N⋯N1	1.03	1.83	2.612 (3)	130
N1—H1N⋯Cl2	1.06	2.73	3.548 (2)	134
N3—H3N⋯Cl2	1.03	2.74	3.477 (3)	129
N2—H2N⋯Cl1ⁱ	0.93	2.39	3.313 (3)	170

Open in a new tab

Symmetry code: (i) Inline graphic .

Acknowledgments

The authors thank the X-ray Laboratory of the University of Chile for the data collection. The authors acknowledge FONDAP (grant No. 11980002) for financial support.

supplementary crystallographic information

Comment

Core to the crystal engineering of supramolecular compounds are the different strategies that are used to control the molecular aggregation processes. For example, the selection of metal ions that promote the formation of extended arrays, and organic molecules capable of forming hydrogen bonding or close packed structures are fundamental to control the molecular aggregation (Guillon et al., 2000, Rice et al., 2002). Therefore, the strategies adopted in the preparation of crystal structures involve two main concepts. One of them is related with the use of the shape-controlled close packing of molecules, and the second one with the use of the specific interactions to control aggregation of molecular species (Guillon et al., 2000).

2,2-Dipyridylamine (DPA) is used as an organic linker presenting different coordination modes ranging from monodentate to chelating bidentate or bridging tridentate. Furthermore, this organic ligand contains the amino group and aromatic rings that may induce intermolecular hydrogen bonding and π-π stacking interactions that may lead to different structures. (Camus, et al. 2000, Bose et al., 2004, Rahaman et al.2005, Chowdhury et al., 2005, Youmgme et al., 2005, Marinescu et al., 2005).

In this work we inform on the synthesis of a novel crystal structure with a tetrachlorozincate anion obtained by hydrothermal synthesis. The reaction conditions described in the experimental section lead to the oxidation of the metallic zinc used as the reducing agent and, to the formation of a crystalline tetrahalide species, which is present together with the cationic counterion, DPAH⁺.

The organic cation (DPAH⁺) exhibits two pyridinium rings in a highly planar arrangement with a dihedral angle between them of only 7.2 (2)°. This is consistent with the value observed for the isostructural cobalt derivative (DPAH⁺)₂[CoCl₄]^2- of the title compound (Visser et al., 1997); both compounds being isostructural. The pyridinium nitrogen atoms on the cation are in a "face to face" (or U) arrangement, allowing the existence of an intramolecular hydrogen bond (see hydrogen bonding table), also observed for other 2-(pyridin-2-ylamino)pyridinium salts such as the Cl^-, squarate (C₄O₄H)^-, tetraphenylborate (B(C₆H₅)₄)^- (Bock et al., 1998) or NO₃^- (Du & Zhao, 2004) compounds. The parameters for this interaction within these salts are basically identical. A different situation is observed for (DPAH²⁺)[CuCl₄]^2- (Willett, 1995) and (DPAH²⁺)(CF₃SO₃)^- (Bock et al., 1998) where the molecule is diprotonated, leading to an S-like conformation which precludes intramolecular hydrogen bonding.

As expected, the tetrachlorozincate anion, with the zinc atom lying on the twofold axis, displays an almost perfect tetrahedral coordination environment. The [ZnCl₄]^2-anion interacts with the cations through weak hydrogen bonds between Cl1 and Cl2 with the DPAH⁺ cations, as summarized in the hydrogen bonding table and depicted in Figure 1. Each tetrachlorozincate anion is bonded in this way to four cations. This differs from what is observed in (DPAH²⁺)[CuCl₄]^2-, where the values N(amine)···Cl = 2.133 Å, N(pyridinium)···Cl = 2.307, 2.470 Å) suggest stronger interactions. The rather strong distortion from square planar geometry in this latter molecule has been addressed to the hydrogen bonding interactions (Willett, 1995).

As can be seen in Figure 1, there are two pairs of strictly parallel cations, which are separated by approximately 3.3 Å, a value that is in the range for π-π interactions (Marinescu et al., 2005), but somewhat shorter than the 3.534 (5) Å reported for (DPAH⁺)NO₃^-(Du & Zhao, 2004). Each pair of DPAH⁺cations is in connected with a neighboring pair in a "head to tail" fashion (see Figure 1), thus leading to a packing arrangement with a zigzag chain with alternating organic cations and tetrachlorozincate anions as seen in Figure 2. These chains interact in the solid by means of π-π contacts.

Experimental

The compound was obtained by hydrothermal synthesis employing the following reagents: CrCl₃.6H₂O, DPA, V₂O₅, Zn, H₃PO₄(85%) and H₂O (all Aldrich, used without further purification) in the following quantities: 0.1523 g, 0.28 g, 0.1438 g, 0.1054 g, 0.58 ml and 5 ml respectively. This mixture was sealed in a 23 ml PTFE-lined stainless steel autoclave, and heated to 393 K (120°C) for 72 h. The yield of the studied compound was approximately 10%, and X-ray quality crystals were directly selected from the bulk mixture of products.