4-tert-Butyl­pyridinium triiodide–4-tert-butyl­pyridine (1/1)

Hongshan He; Andrew G Sykes

doi:10.1107/S1600536811001371

. 2011 Jan 22;67(Pt 2):o434. doi: 10.1107/S1600536811001371

4-tert-Butylpyridinium triiodide–4-tert-butylpyridine (1/1)

Hongshan He ^a,^*, Andrew G Sykes ^b

PMCID: PMC3051785 PMID: 21523100

Abstract

The title compound, C₉H₁₄N⁺·I₃ ⁻·C₉H₁₃N, consists of monoprotonated 4-tert-butylpyridinium cations and triiodide anions. The triiodide ion has near-symmetric linear geometry, with bond lengths of 2.9105 (4) Å (I—I) and a bond angle of 177.55 (3)° (I—I—I). For this room-temperature structure, the butyl group on the pyridine ring is disordered and has been treated as a rigid rotator, modeled in three separate positions with 1/3, 1/3, 1/3 occupancies. The cations assemble into dimeric forms by way of N—H⋯N hydrogen bonds.

Related literature

For applications of the 4-t-butylpyridine and iodide/triiodide system in dye-sensitized solar cells see: Campbell et al. (2004 ▶); Lee et al. (2010 ▶); Wang et al. (2005 ▶). For related structures, see: Fialho et al. (1996 ▶); Kochel (2006 ▶).

Experimental

Crystal data

C₉H₁₄N⁺·I₃ ⁻·C₉H₁₃N
M _r = 652.12
Tetragonal,
a = 11.6862 (4) Å
c = 17.1665 (13) Å
V = 2344.4 (2) Å³
Z = 4
Mo Kα radiation
μ = 4.00 mm⁻¹
T = 293 K
0.55 × 0.50 × 0.40 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T _min = 0.217, T _max = 0.298
23722 measured reflections
2217 independent reflections
1758 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.037
wR(F ²) = 0.090
S = 1.04
2217 reflections
119 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.80 e Å⁻³
Δρ_min = −0.77 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: SAINT (Bruker, 2006 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶), WinGX (Farrugia, 1999 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811001371/sj5091sup1.cif

e-67-0o434-sup1.cif^{(18.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811001371/sj5091Isup2.hkl

e-67-0o434-Isup2.hkl^{(106.9KB, 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—H99⋯N1ⁱ	0.90	1.76	2.655 (7)	172

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Symmetry code: (i) Inline graphic .

Acknowledgments

This material is based upon work supported by the National Science Foundation/EPSCoR grant No. 0903804 and by the State of South Dakota.

supplementary crystallographic information

Comment

4 - t-Butylpyridine is usually added into an iodide/triiodide electrolyte solution to enhance the photovoltaic performance of dye-sensitized solar cells. The solution is a mixture of iodide, lithium iodide, 4 - t-butylpyridine, and guanidinium thiocyanate (Campbell et al., 2004; Lee et al., 2010). Alternatively, the electrolyte can be prepared by the reaction between 2-hydroxypropionitrile and lithium iodide (Wang et al., 2005). It was proposed that triiodide was produced during the reaction; however, no direct evidence was obtained. Reported here is the structure of the resulting compound.

In the molecule of the title compound, three iodide atoms in triiodide ion are in a linear geometry (Fig. 1). The I1—I2 bond length is 2.9105 (4)Å and the I2—I1—I2 angle is 177.55 (3)°. The triiodide bond is almost parallel to the pyridyl ring. In each asymmetric unit cell, two pairs of triiodide ions are perpendicular to each other (Fig. 2 and Fig. 3). The cations assemble into dimeric forms by way of N—H···N hydrogen bonds (Fig. 4, Table 1).

Experimental

2-Hydroxypropionitrile (6.1 g) and lithium iodide (10 g) was added to a flask. The resulting mixture was heated to 120°C in a sealed high pressure tube for 30 minutes. When the temperature decreased to 70°C, silica powder with diameter 25 µm (1.3 g), 4 - t-butylpyridine (1.0 g), and ethanol (3 ml) were added. The mixture was stirred by a mechanical stirrer at 50°C for 30 minutes. Red crystals were obtained from the resulting mixture in one month.