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The β modification of pyridinium di­chloro­iodide, C5H6N+·Cl2I, was obtained as yellow crystals by the reaction of (C5NH5)AuCl3, C5H6N+·Cl and I2 in a vacuum-sealed ampoule. The di­chloro­iodide ion is nearly symmetric and linear with I—Cl bond lengths of 2.544 (3) and 2.550 (3) Å and a Cl—I—Cl angle of 179.68 (12)°.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100000317/br1276sup1.cif
Contains datablocks psi, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100000317/br1276Isup2.hkl
Contains datablock I

CCDC reference: 144642

Comment top

The dichloroiodide ion has been characterized in many compounds, showing different forms (Brandoli et al., 1978; Grebe et al., 1995). Tucker reported the α modification of pyridinium dichloroiodide as trigonal, space group R3 m, with a = 6.165 (4) Å, α = 82.45 (6)° and Z = 1 (Tucker & Kroon, 1973). We present (I), the β modification of this compound that crystallizes in the orthorhombic space group Pnma with a = 8.0390 (5), b = 7.694 (16), c = 14.130 (2) Å and Z = 4. \sch

The title compound is formed during the reaction of (C5NH5)AuCl3, (C5NH6)+Cl- and I2 in a sealed glass ampoule. We also observed the formation of elemental gold. Crystals of good quality were obtained by subsequent sublimation. The asymmetric unit contains a half dichloroiodide anion located on a mirror plane and a half pyridium cation off a mirror plane.

The packing diagram (Fig. 1) shows the pyridium cation packed in stacks along the a axis. The dichloroiodide anion packs with the Cl–I–Cl units parallel in a zigzag pattern along the b axis between the pyridium stacks with a spacing of 4.3931 (10) Å between the anions. The cation-anion (H—Cl) distance of 2.86–2.94 Å (Table 2) is rather shorter than the sum of the van der Waals radii (Pauling, 1960), suggesting that the cation-anion interactions control the packing.

In the β-modification, the deviation of the Cl—I—Cl bond angle [179.68 (12)°] from linearity is not significant. The bond lengths of I—Cl1 = 2.544 (3) Å and I—Cl2 = 2.550 (3) Å can be considered symmetric and have values similar to that already found in similar anions (2.54–2.69 Å) (Bandoli et al., 1978; Grebe et al., 1995). In agreement with another similar structure we are assuming that the cation is sixfold disordered; we have been unable to distingish an ordered (C5NH6)+ ion (Tucker & Kroon, 1973). The pyridinium ion is treated as six symmetry-related C—H groups (occupancy = 5/6) and six related N—H groups (occupancy = 1/6). Selected bond distances and angles are given in Table 1.

Experimental top

The β-piridinium dichloroiodide is formed when (C5NH5)AuCl3, (C5NH6)+Cl- and I2 in the molar ratio 1:1:4 are heated in sealed glass ampoule (diameter = 1.2 cm, length = 20 cm). To obtain high quality crystals it is essential that the temperature is slowly increased between 373 and 523 K. After cooling, β-pyridinium dichloroiodide deposits as yellow single crystals. Element analysis (calculated/found) C 21.60/23.07 H 2.16/2.34 N 5.03/5.07%

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1994); cell refinement: CAD-4 Software; data reduction: HELENA (Spek, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. View of molecule with Cl and I atoms labelled. Displacement ellipsoids are drawn at the 50% probability level.
/b-Pyridinium Dichlroiodide top
Crystal data top
C5H6N+·Cl2IDx = 2.112 Mg m3
Mr = 277.91Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, PnmaCell parameters from 25 reflections
a = 8.0390 (5) Åθ = 5.3–16.3°
b = 7.6940 (16) ŵ = 4.20 mm1
c = 14.130 (2) ÅT = 208 K
V = 874.0 (2) Å3Needle, yellow
Z = 40.20 × 0.10 × 0.05 mm
F(000) = 520
Data collection top
CAD4
diffractometer
Rint = 0.075
Radiation source: fine-focus sealed tubeθmax = 28.0°, θmin = 3.0°
Graphite monochromatorh = 110
ω/2θ scansk = 010
Absorption correction: ψ scan
(North et al., 1968)
l = 181
Tmin = 0.660, Tmax = 0.8113 standard reflections every 200 reflections
1378 measured reflections intensity decay: 5.3%
1129 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.057Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.141H atoms treated by a mixture of independent and constrained refinement
S = 1.05Calculated w = 1/[σ2(Fo2) + (0.0715P)2]
where P = (Fo2 + 2Fc2)/3
1129 reflections(Δ/σ)max < 0.001
46 parametersΔρmax = 1.92 e Å3
0 restraintsΔρmin = 1.11 e Å3
Crystal data top
C5H6N+·Cl2IV = 874.0 (2) Å3
Mr = 277.91Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 8.0390 (5) ŵ = 4.20 mm1
b = 7.6940 (16) ÅT = 208 K
c = 14.130 (2) Å0.20 × 0.10 × 0.05 mm
Data collection top
CAD4
diffractometer
1129 independent reflections
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.075
Tmin = 0.660, Tmax = 0.8113 standard reflections every 200 reflections
1378 measured reflections intensity decay: 5.3%
Refinement top
R[F2 > 2σ(F2)] = 0.0570 restraints
wR(F2) = 0.141H atoms treated by a mixture of independent and constrained refinement
S = 1.05Δρmax = 1.92 e Å3
1129 reflectionsΔρmin = 1.11 e Å3
46 parameters
Special details top

Experimental. PyAuCl3.H2O + PyHCl + I2 —-> [PyH][ICl2] + ···

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 (Å2) top
xyzUiso*/UeqOcc. (<1)
I10.01318 (9)0.25000.07469 (5)0.0409 (3)
Cl10.3121 (4)0.25000.1339 (3)0.0600 (9)
Cl20.2858 (4)0.25000.0144 (2)0.0654 (10)
C10.1723 (12)0.1601 (11)0.2206 (5)0.054 (2)0.83333
H10.18310.09890.16420.065*
C20.1563 (12)0.0739 (13)0.3042 (6)0.061 (2)0.83333
H20.15300.04690.30500.073*
C30.1453 (10)0.1648 (12)0.3867 (5)0.050 (2)0.83333
H30.13760.10510.44380.060*
N10.1723 (12)0.1601 (11)0.2206 (5)0.054 (2)0.16666
N20.1563 (12)0.0739 (13)0.3042 (6)0.061 (2)0.16666
N30.1453 (10)0.1648 (12)0.3867 (5)0.050 (2)0.16666
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
I10.0529 (5)0.0353 (4)0.0345 (4)0.0000.0026 (4)0.000
Cl10.0522 (18)0.063 (2)0.065 (2)0.0000.0063 (17)0.000
Cl20.0536 (19)0.090 (3)0.053 (2)0.0000.0056 (15)0.000
C10.088 (6)0.037 (5)0.038 (4)0.002 (5)0.007 (5)0.005 (4)
C20.098 (7)0.033 (5)0.052 (5)0.004 (5)0.001 (5)0.011 (4)
C30.060 (5)0.055 (6)0.034 (4)0.005 (4)0.010 (4)0.010 (4)
N10.088 (6)0.037 (5)0.038 (4)0.002 (5)0.007 (5)0.005 (4)
N20.098 (7)0.033 (5)0.052 (5)0.004 (5)0.001 (5)0.011 (4)
N30.060 (5)0.055 (6)0.034 (4)0.005 (4)0.010 (4)0.010 (4)
Geometric parameters (Å, º) top
I1—Cl12.544 (3)C1—C21.361 (11)
I1—Cl22.550 (3)C1—C1i1.384 (17)
I1—Cl22.550 (3)C2—C31.363 (11)
Cl2—Cl20.000 (9)C3—C3i1.312 (18)
Cl1—I1—Cl2179.68 (12)C2—C1—C1i119.2 (5)
Cl1—I1—Cl2179.68 (12)C1—C2—C3120.0 (8)
Cl2—I1—Cl20.00 (15)C3i—C3—C2120.9 (5)
Cl2—Cl2—I10 (10)
Symmetry code: (i) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···Cl1ii0.932.913.566 (9)129
C1—H1···Cl20.932.903.512 (8)125
C3—H3···Cl1iii0.932.943.570 (9)127
C3—H3···Cl2iv0.932.863.527 (9)130
Symmetry codes: (ii) x, y, z; (iii) x1/2, y, z1/2; (iv) x1/2, y, z1/2.

Experimental details

Crystal data
Chemical formulaC5H6N+·Cl2I
Mr277.91
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)208
a, b, c (Å)8.0390 (5), 7.6940 (16), 14.130 (2)
V3)874.0 (2)
Z4
Radiation typeMo Kα
µ (mm1)4.20
Crystal size (mm)0.20 × 0.10 × 0.05
Data collection
DiffractometerCAD4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.660, 0.811
No. of measured, independent and
observed (?) reflections
1378, 1129, ?
Rint0.075
(sin θ/λ)max1)0.660
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.057, 0.141, 1.05
No. of reflections1129
No. of parameters46
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)1.92, 1.11

Computer programs: CAD-4 Software (Enraf-Nonius, 1994), CAD-4 Software, HELENA (Spek, 1995), SHELXS97 (Sheldrick, 1997a), SHELXL97 (Sheldrick, 1997b), ORTEP-3 for Windows (Farrugia, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
I1—Cl12.544 (3)C1—C1i1.384 (17)
I1—Cl22.550 (3)C2—C31.363 (11)
C1—C21.361 (11)C3—C3i1.312 (18)
Cl1—I1—Cl2179.68 (12)C1—C2—C3120.0 (8)
C2—C1—C1i119.2 (5)C3i—C3—C2120.9 (5)
Symmetry code: (i) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···Cl1ii0.932.913.566 (9)128.8
C1—H1···Cl20.932.903.512 (8)124.7
C3—H3···Cl1iii0.932.943.570 (9)126.6
C3—H3···Cl2iv0.932.863.527 (9)129.5
Symmetry codes: (ii) x, y, z; (iii) x1/2, y, z1/2; (iv) x1/2, y, z1/2.
 

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