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Acta Cryst. (2009). E65, m402    [ doi:10.1107/S1600536809007090 ]

Low-temperature rerefinement of nonmerohedrally twinned tripyridinium bis[tetrabromidoferrate(III)] bromide

S. W. Ng

Abstract top

The asymmetric unit of the title double salt, (C5H6N)3[FeBr4]2Br, consists of three pyridinium cations, two tetrahedral bromidoferrate(III) anions and a bromide anion. The three cations each form one N-H...Br hydrogen bond to the bromide anion. The crystal under investigation was a non-merohedral twin, with a portion of 22% for the minor twin component.

Related literature top

The authors of the original room-temperature study noted twinning but the refinement program then could not take this into consideration; see: Lowe et al. (1994).

Experimental top

The crystals were provided by Dr. Nasser Safari of Shahid Beheshti University. Pyridine (2.2 ml, 25 mmol) was added to a solution of ferric bromide (1.25 g, 4.23 mmol) dissolved in a mixture of 1.2 M hydrobromic acid and 2.4 M acetic acid (20 ml). The red solution was set aside for two weeks, after which crystals separated out.

Refinement top

The refinement initally converged to an R1 value of 0.088, but there were large peaks/deep holes. The crystal is in fact a nonmerohedral twin. The law, as given by PLATON (Spek, 2003), is (-1 0 0, 0 - 1 0, 0.323 0 1). The refinement, with an approximate twin component of 22%, halved the R1 index. The twinning affected the anisotropic temperature factors of the carbon and nitrogen atoms; these were restrained to be nearly isotropic.

Carbon- and nitrogen-bound H-atoms were placed in calculated positions (C–H 0.95, N–H 0.88 Å) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U(C,N).

The final difference Fourier map had large peaks/holes in the vicinity of the bromide atoms.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2009).

Figures top
[Figure 1] Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of [C5H6N]3[FeBr4]2[Br].
tripyridinium bis[tetrabromidoferrate(III)] bromide top
Crystal data top
(C5H6N)3[FeBr4]2BrF(000) = 992
Mr = 1071.21Dx = 2.487 Mg m−3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 8983 reflections
a = 7.5602 (1) Åθ = 2.7–28.3°
b = 14.0125 (2) ŵ = 13.59 mm−1
c = 13.5609 (2) ÅT = 123 K
β = 95.172 (1)°Irregular block, brown
V = 1430.76 (3) Å30.30 × 0.25 × 0.20 mm
Z = 2
Data collection top
Bruker SMART APEX
diffractometer		6460 independent reflections
Radiation source: fine-focus sealed tube6006 reflections with I > 2σ(I)
graphiteRint = 0.038
ω scansθmax = 27.5°, θmin = 1.5°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −9→9
Tmin = 0.098, Tmax = 0.154k = −18→18
13428 measured reflectionsl = −17→17
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.043H-atom parameters constrained
wR(F2) = 0.106 w = 1/[σ2(Fo2) + (0.0502P)2 + 4.7139P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max = 0.001
6460 reflectionsΔρmax = 1.29 e Å−3
263 parametersΔρmin = −1.71 e Å−3
109 restraintsAbsolute structure: Flack (1983), 3046 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.10 (2)
Crystal data top
(C5H6N)3[FeBr4]2BrV = 1430.76 (3) Å3
Mr = 1071.21Z = 2
Monoclinic, P21Mo Kα radiation
a = 7.5602 (1) ŵ = 13.59 mm−1
b = 14.0125 (2) ÅT = 123 K
c = 13.5609 (2) Å0.30 × 0.25 × 0.20 mm
β = 95.172 (1)°
Data collection top
Bruker SMART APEX
diffractometer		6460 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		6006 reflections with I > 2σ(I)
Tmin = 0.098, Tmax = 0.154Rint = 0.038
13428 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.043H-atom parameters constrained
wR(F2) = 0.106Δρmax = 1.29 e Å−3
S = 1.07Δρmin = −1.71 e Å−3
6460 reflectionsAbsolute structure: Flack (1983), 3046 Friedel pairs
263 parametersFlack parameter: 0.10 (2)
109 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br10.27784 (12)0.49992 (6)0.74070 (6)0.02428 (19)
Br20.27108 (13)0.35971 (6)0.50468 (7)0.0250 (2)
Br30.02833 (11)0.60181 (6)0.50814 (7)0.02457 (19)
Br40.52742 (11)0.59765 (7)0.52624 (7)0.0268 (2)
Br50.52708 (11)0.89250 (6)0.95876 (7)0.02335 (19)
Br60.75284 (12)1.00789 (7)0.74713 (6)0.02522 (19)
Br71.02585 (12)0.91096 (8)0.97548 (8)0.0356 (3)
Br80.74006 (15)1.13935 (7)0.98802 (7)0.0350 (2)
Br90.74762 (11)0.65558 (7)0.83903 (6)0.02359 (19)
Fe10.27879 (15)0.51483 (9)0.56879 (9)0.0177 (2)
Fe20.76356 (16)0.98860 (9)0.91855 (9)0.0197 (3)
N10.7426 (11)0.4395 (6)0.7619 (7)0.038 (2)
H10.74270.49310.79590.045*
N20.7876 (12)0.7029 (7)1.0778 (6)0.0343 (19)
H20.79930.72331.01730.041*
N30.3634 (10)0.7457 (5)0.7543 (5)0.0203 (15)
H30.43240.70320.78630.024*
C10.8048 (15)0.4412 (10)0.6741 (9)0.047 (3)
H1A0.84570.49880.64700.056*
C20.8080 (17)0.3569 (11)0.6239 (9)0.054 (3)
H2A0.85820.35490.56220.065*
C30.7408 (16)0.2758 (9)0.6606 (10)0.048 (3)
H3A0.73630.21820.62340.058*
C40.6797 (14)0.2790 (8)0.7523 (9)0.038 (2)
H40.63710.22260.78100.046*
C50.6802 (15)0.3618 (9)0.8016 (7)0.038 (2)
H50.63570.36470.86490.046*
C60.7428 (14)0.6150 (8)1.0919 (7)0.035 (2)
H60.72460.57381.03630.042*
C70.7210 (16)0.5797 (8)1.1832 (9)0.041 (3)
H70.68730.51511.19190.049*
C80.7500 (12)0.6418 (8)1.2642 (7)0.032 (2)
H80.73610.61991.32940.039*
C90.7984 (14)0.7340 (8)1.2482 (7)0.035 (2)
H90.81920.77711.30210.042*
C100.8163 (16)0.7633 (7)1.1548 (8)0.039 (2)
H100.84970.82741.14330.047*
C110.1903 (12)0.7447 (6)0.7669 (6)0.0208 (17)
H110.14350.69890.80920.025*
C120.0815 (12)0.8104 (7)0.7182 (6)0.0260 (18)
H12−0.04200.81020.72620.031*
C130.1503 (13)0.8766 (6)0.6576 (7)0.0256 (19)
H130.07570.92310.62410.031*
C140.3330 (13)0.8744 (6)0.6459 (7)0.0260 (19)
H140.38310.91900.60350.031*
C150.4375 (12)0.8082 (7)0.6956 (7)0.0269 (19)
H150.56140.80620.68880.032*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0313 (4)0.0211 (4)0.0195 (4)−0.0010 (4)−0.0025 (3)−0.0005 (3)
Br20.0325 (5)0.0188 (4)0.0241 (4)−0.0009 (4)0.0039 (4)−0.0032 (3)
Br30.0164 (4)0.0285 (5)0.0285 (4)0.0046 (4)0.0009 (3)0.0077 (4)
Br40.0168 (4)0.0268 (5)0.0369 (5)−0.0041 (4)0.0030 (3)0.0016 (4)
Br50.0181 (4)0.0236 (4)0.0286 (4)−0.0015 (3)0.0038 (3)0.0022 (3)
Br60.0311 (4)0.0272 (4)0.0175 (4)0.0014 (4)0.0031 (3)0.0012 (4)
Br70.0186 (4)0.0520 (7)0.0356 (5)0.0033 (4)−0.0007 (4)0.0137 (5)
Br80.0507 (6)0.0292 (6)0.0246 (5)−0.0099 (5)0.0008 (4)−0.0090 (4)
Br90.0204 (4)0.0272 (5)0.0225 (4)0.0047 (4)−0.0019 (3)−0.0033 (3)
Fe10.0153 (5)0.0167 (6)0.0206 (6)0.0002 (5)−0.0005 (4)−0.0003 (5)
Fe20.0186 (5)0.0230 (6)0.0173 (6)−0.0020 (5)0.0003 (4)0.0008 (5)
N10.025 (4)0.030 (4)0.056 (5)0.003 (3)−0.013 (4)−0.012 (4)
N20.038 (4)0.043 (5)0.023 (4)0.011 (4)0.010 (3)0.009 (3)
N30.020 (3)0.019 (3)0.021 (3)−0.002 (3)−0.006 (3)0.002 (3)
C10.030 (5)0.055 (6)0.055 (6)−0.009 (5)−0.004 (4)0.028 (5)
C20.042 (6)0.083 (8)0.038 (5)0.003 (6)0.009 (5)0.000 (6)
C30.040 (5)0.047 (6)0.056 (6)0.008 (5)−0.005 (5)−0.021 (5)
C40.028 (5)0.028 (5)0.055 (6)−0.007 (4)−0.013 (4)0.016 (4)
C50.036 (5)0.058 (6)0.021 (4)0.001 (5)0.005 (4)−0.002 (4)
C60.043 (5)0.035 (5)0.024 (4)0.013 (4)−0.011 (4)−0.005 (4)
C70.044 (5)0.026 (5)0.051 (6)−0.013 (4)−0.009 (5)0.005 (4)
C80.028 (4)0.045 (5)0.024 (4)0.000 (4)−0.001 (3)0.010 (4)
C90.037 (5)0.039 (5)0.029 (5)−0.002 (4)0.004 (4)−0.013 (4)
C100.049 (5)0.022 (4)0.048 (5)0.002 (4)0.010 (5)0.001 (4)
C110.023 (4)0.019 (4)0.021 (4)−0.002 (3)0.004 (3)−0.001 (3)
C120.023 (4)0.031 (4)0.025 (4)0.001 (4)0.004 (3)−0.004 (3)
C130.027 (4)0.020 (4)0.029 (4)0.008 (4)0.001 (3)0.005 (3)
C140.028 (4)0.020 (4)0.031 (4)−0.010 (3)0.008 (4)0.005 (3)
C150.021 (4)0.032 (4)0.028 (4)−0.007 (4)−0.003 (3)−0.003 (4)
Geometric parameters (Å, °) top
Br1—Fe12.341 (2)C3—H3A0.9500
Br2—Fe12.340 (2)C4—C51.340 (16)
Br3—Fe12.338 (1)C4—H40.9500
Br4—Fe12.326 (1)C5—H50.9500
Br5—Fe22.342 (1)C6—C71.357 (15)
Br6—Fe22.335 (1)C6—H60.9500
Br7—Fe22.331 (2)C7—C81.404 (15)
Br8—Fe22.326 (2)C7—H70.9500
N1—C11.319 (15)C8—C91.366 (15)
N1—C51.320 (15)C8—H80.9500
N1—H10.8800C9—C101.349 (15)
N2—C61.296 (14)C9—H90.9500
N2—C101.347 (14)C10—H100.9500
N2—H20.8800C11—C121.364 (13)
N3—C111.335 (11)C11—H110.9500
N3—C151.340 (12)C12—C131.372 (13)
N3—H30.8800C12—H120.9500
C1—C21.36 (2)C13—C141.405 (13)
C1—H1A0.9500C13—H130.9500
C2—C31.357 (19)C14—C151.358 (13)
C2—H2A0.9500C14—H140.9500
C3—C41.366 (17)C15—H150.9500
Br4—Fe1—Br3107.44 (6)N1—C5—C4119.7 (9)
Br4—Fe1—Br2111.41 (6)N1—C5—H5120.2
Br3—Fe1—Br2111.18 (6)C4—C5—H5120.2
Br4—Fe1—Br1111.51 (6)N2—C6—C7122.4 (10)
Br3—Fe1—Br1108.77 (6)N2—C6—H6118.8
Br2—Fe1—Br1106.55 (6)C7—C6—H6118.8
Br8—Fe2—Br7112.54 (6)C6—C7—C8117.7 (10)
Br8—Fe2—Br6107.52 (6)C6—C7—H7121.1
Br7—Fe2—Br6109.63 (6)C8—C7—H7121.1
Br8—Fe2—Br5109.89 (6)C9—C8—C7119.1 (9)
Br7—Fe2—Br5107.40 (6)C9—C8—H8120.4
Br6—Fe2—Br5109.86 (6)C7—C8—H8120.4
C1—N1—C5123.5 (10)C10—C9—C8119.2 (10)
C1—N1—H1118.2C10—C9—H9120.4
C5—N1—H1118.2C8—C9—H9120.4
C6—N2—C10120.6 (9)N2—C10—C9121.0 (10)
C6—N2—H2119.7N2—C10—H10119.5
C10—N2—H2119.7C9—C10—H10119.5
C11—N3—C15123.4 (8)N3—C11—C12119.1 (8)
C11—N3—H3118.3N3—C11—H11120.4
C15—N3—H3118.3C12—C11—H11120.4
N1—C1—C2117.3 (11)C11—C12—C13120.1 (8)
N1—C1—H1A121.4C11—C12—H12120.0
C2—C1—H1A121.4C13—C12—H12120.0
C3—C2—C1121.2 (11)C12—C13—C14118.9 (8)
C3—C2—H2A119.4C12—C13—H13120.6
C1—C2—H2A119.4C14—C13—H13120.6
C2—C3—C4118.3 (11)C15—C14—C13119.5 (8)
C2—C3—H3A120.8C15—C14—H14120.3
C4—C3—H3A120.8C13—C14—H14120.3
C5—C4—C3119.8 (10)N3—C15—C14119.1 (8)
C5—C4—H4120.1N3—C15—H15120.5
C3—C4—H4120.1C14—C15—H15120.5
C5—N1—C1—C2−1.8 (17)C7—C8—C9—C100.3 (17)
N1—C1—C2—C33.5 (19)C6—N2—C10—C9−0.3 (17)
C1—C2—C3—C4−4.1 (19)C8—C9—C10—N2−0.2 (17)
C2—C3—C4—C52.9 (18)C15—N3—C11—C12−0.2 (13)
C1—N1—C5—C40.6 (17)N3—C11—C12—C13−0.3 (13)
C3—C4—C5—N1−1.2 (17)C11—C12—C13—C140.9 (14)
C10—N2—C6—C70.7 (16)C12—C13—C14—C15−1.0 (14)
N2—C6—C7—C8−0.5 (17)C11—N3—C15—C140.1 (13)
C6—C7—C8—C90.0 (16)C13—C14—C15—N30.5 (14)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1···Br90.882.353.202 (9)163
N2—H2···Br90.882.593.292 (8)137
N3—H3···Br90.882.523.279 (7)146
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1···Br90.882.353.202 (9)163
N2—H2···Br90.882.593.292 (8)137
N3—H3···Br90.882.523.279 (7)146
Acknowledgements top

I thank the University of Malaya for supporting this study.

references
References top

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Bruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.

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Lowe, C. B., Schultz, A. J., Shaviv, R. & Carlin, R. L. (1994). Inorg. Chem. 33, 3051–3054.

Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.

Westrip, S. P. (2009). publCIF. In preparation.