2,5-Dibromo­pyridinium hexa­bromidostannate(IV)

The asymmetric unit of the title compound, (C₅H₄Br₂N)₂[SnBr₆], contains one cation and one half-anion. The anion exhibits a distorted octa­hedral arrangement about the Sn atom, which lies on a crystallographic twofold rotation axis. In the crystal structure, inter­molecular hydrogen bonds and short Br...Br inter­actions cause the formation of a supra­molecular architecture, in which they may be effective in the stabilization of the structure.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.010 Å
• R factor = 0.039
• wR factor = 0.048
• Data-to-parameter ratio = 20.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Sn1
PLAT342_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...         10
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  Br5     ..       3.44 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.23
           From the CIF: _reflns_number_total               2126
           Count of symmetry unique reflns         1203
           Completeness (_total/calc)            176.72%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       923
           Fraction of Friedel pairs measured     0.767
           Are heavy atom types Z>Si present        yes

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXP97 (Sheldrick, 1997); software used to prepare material for publication: SHELXCIF97 (Sheldrick, 1997).

2,5-Dibromopyridinium hexabromidostannate(IV)

Crystal data

(C5H4Br2N)2[SnBr6]	Dx = 3.047 Mg m^−3
Mr = 1073.89	Mo Kα radiation, λ = 0.71070 Å
Tetragonal, I42d	Cell parameters from 9875 reflections
Hall symbol: I -4 2bw	θ = 1.2–27.9°
a = 24.566 (4) Å	µ = 18.16 mm^−1
c = 7.7555 (12) Å	T = 294 K
V = 4680.4 (13) Å^3	Block, yellow
Z = 8	0.20 × 0.20 × 0.10 mm
F(000) = 3856

Data collection

Rigaku Mercury diffractometer	2126 independent reflections
Radiation source: fine-focus sealed tube	2120 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.063
Detector resolution: 14.6306 pixels mm^-1	θmax = 25.2°, θmin = 2.3°
data integrate scans	h = −29→29
Absorption correction: numerical Shape Tracing Software [Please provide reference]	k = −29→23
Tmin = 0.044, Tmax = 0.163	l = −9→9
26765 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.039	w = 1/[σ^2(Fo^2)]
wR(F^2) = 0.048	(Δ/σ)max = 0.001
S = 1.21	Δρmax = 0.39 e Å^−3
2126 reflections	Δρmin = −0.40 e Å^−3
106 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.000518 (16)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1442 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.008 (13)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Sn1	0.59942 (2)	0.2500	0.1250	0.02781 (16)
Br2	0.67475 (3)	0.25444 (3)	−0.10868 (10)	0.04030 (19)
Br3	0.52636 (3)	0.24040 (3)	0.36258 (10)	0.0435 (2)
Br1	0.59987 (3)	0.14399 (3)	0.09574 (10)	0.0467 (2)
Br4	0.74778 (3)	0.12955 (3)	0.62230 (12)	0.0543 (2)
Br5	0.49036 (3)	0.08634 (4)	0.52186 (12)	0.0678 (3)
C2	0.6750 (3)	0.1125 (3)	0.5845 (9)	0.0393 (19)
C5	0.5661 (3)	0.0954 (3)	0.5487 (9)	0.0423 (18)
C3	0.6572 (3)	0.0692 (3)	0.4917 (10)	0.044 (2)
H3A	0.6820	0.0455	0.4409	0.053*
C4	0.6027 (3)	0.0607 (3)	0.4733 (9)	0.047 (2)
H4A	0.5903	0.0312	0.4094	0.056*
C6	0.5840 (3)	0.1382 (3)	0.6383 (10)	0.0408 (18)
H6A	0.5595	0.1626	0.6867	0.049*
N1	0.6377 (3)	0.1455 (2)	0.6579 (7)	0.0442 (17)
H1A	0.6488	0.1723	0.7199	0.053*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sn1	0.0293 (4)	0.0242 (3)	0.0299 (3)	0.000	0.000	0.0011 (3)
Br2	0.0362 (4)	0.0423 (4)	0.0424 (4)	−0.0059 (3)	0.0106 (3)	−0.0037 (4)
Br3	0.0377 (4)	0.0517 (5)	0.0412 (4)	0.0034 (3)	0.0096 (4)	0.0096 (4)
Br1	0.0669 (5)	0.0244 (4)	0.0486 (5)	−0.0031 (4)	0.0000 (5)	0.0006 (4)
Br4	0.0452 (4)	0.0589 (5)	0.0589 (5)	−0.0089 (4)	−0.0075 (6)	−0.0031 (4)
Br5	0.0414 (5)	0.0844 (7)	0.0776 (7)	−0.0051 (5)	−0.0037 (4)	0.0010 (6)
C2	0.034 (4)	0.046 (5)	0.038 (5)	0.004 (4)	−0.004 (4)	0.006 (4)
C5	0.040 (4)	0.049 (5)	0.038 (4)	−0.001 (4)	−0.004 (4)	0.006 (4)
C3	0.043 (5)	0.037 (5)	0.052 (5)	0.006 (4)	−0.007 (4)	−0.015 (4)
C4	0.058 (6)	0.040 (5)	0.042 (5)	0.000 (4)	−0.015 (4)	−0.007 (4)
C6	0.038 (5)	0.045 (5)	0.039 (4)	0.006 (4)	−0.003 (4)	0.001 (4)
N1	0.061 (5)	0.038 (4)	0.034 (4)	−0.003 (3)	−0.002 (3)	−0.012 (3)

Geometric parameters (Å, º)

Sn1—Br3^i	2.5830 (9)	C2—C3	1.356 (9)
Sn1—Br3	2.5830 (9)	C5—C6	1.334 (9)
Sn1—Br2^i	2.5925 (9)	C5—C4	1.370 (10)
Sn1—Br2	2.5925 (9)	C3—C4	1.363 (9)
Sn1—Br1	2.6141 (9)	C3—H3A	0.9300
Sn1—Br1^i	2.6141 (9)	C4—H4A	0.9300
Br4—C2	1.860 (7)	C6—N1	1.339 (8)
Br5—C5	1.886 (7)	C6—H6A	0.9300
C2—N1	1.349 (8)	N1—H1A	0.8600
Br3^i—Sn1—Br3	91.96 (13)	C3—C2—Br4	124.7 (6)
Br3^i—Sn1—Br2^i	176.87 (3)	C6—C5—C4	119.8 (7)
Br3—Sn1—Br2^i	89.63 (12)	C6—C5—Br5	118.4 (6)
Br3^i—Sn1—Br2	89.63 (12)	C4—C5—Br5	121.7 (6)
Br3—Sn1—Br2	176.87 (3)	C2—C3—C4	119.4 (7)
Br2^i—Sn1—Br2	88.91 (13)	C2—C3—H3A	120.3
Br3^i—Sn1—Br1	91.83 (3)	C4—C3—H3A	120.3
Br3—Sn1—Br1	88.50 (3)	C3—C4—C5	120.3 (7)
Br2^i—Sn1—Br1	90.90 (3)	C3—C4—H4A	119.9
Br2—Sn1—Br1	88.75 (3)	C5—C4—H4A	119.9
Br3^i—Sn1—Br1^i	88.50 (3)	C5—C6—N1	119.3 (7)
Br3—Sn1—Br1^i	91.83 (3)	C5—C6—H6A	120.4
Br2^i—Sn1—Br1^i	88.75 (3)	N1—C6—H6A	120.4
Br2—Sn1—Br1^i	90.90 (3)	C6—N1—C2	122.7 (6)
Br1—Sn1—Br1^i	179.52 (4)	C6—N1—H1A	118.7
N1—C2—C3	118.5 (6)	C2—N1—H1A	118.7
N1—C2—Br4	116.8 (5)
N1—C2—C3—C4	0.9 (11)	C4—C5—C6—N1	−2.2 (11)
Br4—C2—C3—C4	179.7 (5)	Br5—C5—C6—N1	−179.6 (5)
C2—C3—C4—C5	−0.3 (11)	C5—C6—N1—C2	2.8 (11)
C6—C5—C4—C3	1.0 (11)	C3—C2—N1—C6	−2.2 (10)
Br5—C5—C4—C3	178.3 (5)	Br4—C2—N1—C6	178.9 (5)

Symmetry code: (i) x, −y+1/2, −z+1/4.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3A···Br3^ii	0.93	2.92	3.566 (9)	128
N1—H1A···Br2^iii	0.86	2.50	3.357 (7)	175

Symmetry codes: (ii) −y+1, −x+1/2, z+1/4; (iii) x, y, z+1.