Bis(4-amino­pyridinium) tetra­iodido­cad­mate monohydrate

Qiaozhen Sun; Songyi Liao; Junjun Yao; Junke Wang; Qiongjiali Fang

doi:10.1107/S1600536812034447

. 2012 Aug 8;68(Pt 9):m1160–m1161. doi: 10.1107/S1600536812034447

Bis(4-aminopyridinium) tetraiodidocadmate monohydrate

Qiaozhen Sun ^a,^*, Songyi Liao ^a, Junjun Yao ^a, Junke Wang ^a, Qiongjiali Fang ^a

PMCID: PMC3435586 PMID: 22969459

Abstract

The title compound, (C₅H₇N₂)₂[CdI₄]·H₂O, contains one [CdI₄]²⁻ anion, two prontonated 4-aminopyridine molecules and one water molecule in the asymmetric unit. In the anion, the Cd^II atom is coordinated by four I atoms in a slightly distorted tetrahedral geometry. The [CdI₄]²⁻ anion and the water molecule are bisected by a crystallographic mirror plane perpendicular to the c-axis direction, with the Cd^II atom, two of the I atoms and the atoms of the water molecule located on this plane. The crystal packing is stabilized by intermolecular N—H⋯I, N—H⋯O and O—H⋯I hydrogen bonds and by π–π stacking interactions [centroid–centroid distance = 3.798 (3) Å) between pyridine rings, which build up a three-dimensional network.

Related literature

For background literature on the magnetism, antiviral activity and luminescence of organic–inorganic hybrid compounds, see: Bauer et al. (2003 ▶); Cavicchioli et al. (2010 ▶); Li et al. (2007 ▶). For ion channel inhibitor properties of 4-aminopyridine, see: Picolo et al. (2003 ▶). For metal complexes of 4-aminopyridine, see: Das et al. (2010 ▶); Ivanova et al. (2005 ▶); Jebas et al. (2009 ▶); Kulicka et al. (2006 ▶); Rademeyer et al. (2007 ▶); Zaouali Zgolli et al. (2009 ▶). For bond-length data, see: Anderson et al. (2005 ▶); Hines et al. (2006 ▶).

Experimental

Crystal data

(C₅H₇N₂)₂[CdI₄]·H₂O
M _r = 828.27
Orthorhombic,
a = 7.3987 (2) Å
b = 14.7348 (4) Å
c = 18.7286 (4) Å
V = 2041.76 (9) Å³
Z = 4
Mo Kα radiation
μ = 7.12 mm⁻¹
T = 293 K
0.40 × 0.24 × 0.20 mm

Data collection

Bruker SMART CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.145, T _max = 0.340
11964 measured reflections
1860 independent reflections
1755 reflections with I > 2σ(I)
R _int = 0.052

Refinement

R[F ² > 2σ(F ²)] = 0.025
wR(F ²) = 0.064
S = 1.02
1860 reflections
102 parameters
3 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.91 e Å⁻³
Δρ_min = −0.72 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); 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.

Supplementary Material

Crystal structure: contains datablock(s) global. DOI: 10.1107/S1600536812034447/zl2495sup1.cif

e-68-m1160-sup1.cif^{(14.7KB, cif)}

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—H1B⋯OW1ⁱ	0.86	2.03	2.886 (5)	173
N2—H2A⋯I2ⁱⁱ	0.86	3.12	3.938 (4)	161
N2—H2B⋯I2	0.86	3.04	3.843 (4)	157
OW1—HW1A⋯I2ⁱⁱ	0.83 (2)	3.24 (1)	3.828 (4)	130 (1)
OW1—HW1A⋯I2ⁱⁱⁱ	0.83 (2)	3.24 (1)	3.828 (4)	130 (1)
OW1—HW1A⋯I1	0.83 (2)	3.27 (4)	3.704 (5)	116 (3)
OW1—HW1B⋯I3^iv	0.85 (2)	2.99 (2)	3.761 (5)	152 (4)
OW1—HW1A⋯I1	0.83 (2)	3.27 (4)	3.704 (5)	116 (3)

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

Acknowledgments

The authors acknowledge financial support from the Postdoctoral Science Foundation of Central South University and the Fundamental Research Funds for the Central Universities.

supplementary crystallographic information

Comment

Studies of hydrogen bonds connecting organic-inorganic hybrid compounds continue to be a topic of intense research in crystal engineering because such compounds not only allow for rational bottom-up construction but hydrogen bonds also effectively regulate the molecular architecture. Hydrogen bond connected organic-inorganic hybrid compounds can exhibit novel properties related to e.g magnetism, luminescence, antiviral activity and even multifunctional properties (Bauer et al., 2003; Cavicchioli et al., 2010; Li et al., 2007). The protonated form of 4-aminopyridine (4-AP) has hydrogen-bonding capability at both ends of the molecule, and it is also biologically active and can be used as a K⁺ and Ca²⁺ channel inhibitor (Picolo et al., 2003). Structures of 4-AP with the metals Mn^II, Co^II, Cu^II, Ni^II, Sn^IV, Sb^V and Pd^II have been reported (Das et al., 2010; Ivanova et al., 2005; Jebas et al., 2009; Kulicka et al., 2006; Rademeyer et al., 2007; Zaouali Zgolli et al., 2009). Here we report the crystal structure of the title compound, which is a salt that comprises two symmetry related 4-AP cations and a complex [CdI₄]^2- anion, Fig. 1. The [CdI₄]^2- anion and the water molecule are bisected by a crystallographic mirror plane perpendicular to the c-axis direction, with the the atoms Cd1, I1, I3 and the water molecule located on this plane at x, y, 1/4. In the anion, the Cd^II ion is coordinated by four I atoms, exhibiting a slightly distorted tetrahedral geometry. The mean Cd···I bond distance is 2.78 Å, which is similar to that of related compounds reported in the literature (Hines et al., 2006).

In the cation, the nitrogen atom of the pyridine ring is protonated. Both of the nitrogen atoms of 4-AP are not metal coordinated, but are instead involved in an extensive hydrogen bonding network that includes the amine hydrogen atoms and the iodine atoms, the protonated pyridyl hydrogen atom, and the water molecule. The bond distances and bond angles of the 4-AP cation are comparable with values reported earlier for its uncomplexed form (Anderson et al., 2005).

Packing of the title complex (Fig. 2 and Fig. 3) is facilitated through π–π interactions between pyridine rings [ring centroid distance: 3.798 (3) Å], through the N—H···I hydrogen bonds between the [CdI₄]^2- anions and the 4-AP cations, and through O—H···I and N—H···O hydrogen bonds, which link the components of the structure into a three dimensional network.

Experimental

A mixture of CdI₂ (0.36 g, 0.98 mmol), pyridine-2,3-dicarboxylic acid (0.08 g, 0.48 mmol), and 4-aminopyridine (0.06 g, 0.64 mmol) in H₂O (12.0 mL) was sealed in a 20 mL stainless-steal reactor with Teflon liner and heated at 423 K for 60 h under autogenous pressure. Colorless block crystals were collected after the reaction solution was cooled. Yield: 16%. IR: 3314(s), 1653(s), 1608(s), 1526(s), 1407(s), 1197(m), 993(m), 865(w), 806(m), 758(m), 715(w), 495(m).