4-Cyano­anilinium iodide

In the title compound, C₇H₇N₂⁺·I⁻, the cation is located on a site of 4mm symmetry and is thus disordered about the fourfold axis so that there are two perpendicular orientations of the six-membered ring and four rotational orientations of the {–NH₃⁺} group. In the crystal, there are two layers perpendicular to the c axis, each containing iodide ions and the {–NH₃⁺} portions of the cations, with the remainder of the cations extending outwards from these layers.

Related literature

For the structure of 4-cyano­anilinium chloride, see: Colapietro et al. (1981). For the structure of 4-cyano­anilinium bromide, see: Vumbaco et al. (2012). For the structure of anilinium iodide, see: Fecher & Weiss (1986).

Experimental

Crystal data

• C₇H₇N₂⁺·I⁻

• M_r = 246.05

• Tetragonal, P 4/n m m

• a = 4.9930 (4) Å

• c = 16.445 (2) Å

• V = 409.98 (8) ų

• Z = 2

• Mo Kα radiation

• μ = 3.83 mm⁻¹

• T = 100 K

• 0.26 × 0.20 × 0.05 mm

Data collection

• Bruker SMART APEX CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 2009) T_min = 0.362, T_max = 0.844

• 7082 measured reflections

• 382 independent reflections

• 381 reflections with I > 2σ(I)

• R_int = 0.039

Refinement

• R[F² > 2σ(F²)] = 0.012

• wR(F²) = 0.029

• S = 1.14

• 382 reflections

• 31 parameters

• H-atom parameters constrained

• Δρ_max = 0.46 e Å⁻³

• Δρ_min = −0.56 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯I1	0.88	2.72	3.5813 (5)	165
N1—H1A⋯I1^i	0.88	2.87	3.5813 (5)	139
N1—H1B⋯I1^ii	0.88	2.87	3.5813 (5)	139
Symmetry codes: (i) x-1, y, z; (ii) x, y-1, z.

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL).

Supporting information

S1. Comment

In the title compound, (C₇H₇N₂)⁺.I^-, the cation is located on a site of 4mm symmetry so is disordered over 2 sites rotated 90° from one another about the N1—C1···C4—C5≡N2 axis. This leads to a more extensive disorder of the (—NH₃⁺) group so it is likely that there are a variety of N—H···I interactions of different geometries. To illustrate what one set of these could be, the best estimate of the rotational orientation of the (—NH₃⁺) group obtained from a difference map was used to generate the values given in Table 1. These interactions lead to a layer of anions with the (—NH₃⁺) groups largely in the layer and the remainder of the cations projecting perpendicular to the layer. Two of these layers are then associated in a head–to–head fashion via electrostatic N1⁺···I1^- interactions of 3.513 (1)Å leading to a bilayer of iodide and (—NH₃⁺) groups with the remainders of the cations projecting out from both sides (Fig. 2). A similar layer structure is adopted by anilinium iodide (Fecher & Weiss, 1986) while the packings for 4–cyanoanilinium bromide (Vumbaco et al., 2012) and the corresponding chloride salt (Colapietro et al., 1981) are quite different.

Related literature

For the structure of 4-cyanoanilinium chloride, see: Colapietro et al. (1981). For the structure of 4-cyanoanilinium bromide, see: Vumbaco et al. (2012). For the structure of anilinium iodide, see: Fecher & Weiss (1986).

S2. Experimental

The 0.55 g of 4–cyanoaniline and 1.0 ml of aqueous hydroiodic acid (47% by mass) were combined in 10 ml of ethanol. This solution was slowly evaporated to dryness under ambient conditions to form crystals of the title compound.

S3. Refinement

The cation sits on a special position requiring 4 mm symmetry with the 4–fold axis running through both N atoms and the attached carbons. Thus the carbon atoms at the 2– and 3–positions are effectively disordered over two sites and two orientations of each were used in the refinement. H atoms attached to these carbons were placed in calculated positions with C—H = 0.95Å. A small peak in a position to be one location for a hydrogen bound to N1 could be seen in a difference map and its position was used to calculate positions for the remainder of one of the orientations of the —NH₃⁺ unit in which the N—H distance was adjusted to be 0.88Å. All H atoms were included as riding contributions with U_iso(H) = 1.2U_eq(C, N).

Computing details

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. View of the cation–anion pair with with the atom numbering scheme. Displacement ellipsoids are drawn at 50% probability level. H atoms are presented as a small spheres of arbitrary radius. Symmetry code: (i) -x+1/2, -y+1/2, z.
	Fig. 2. Packing showing the cation–anion bilayer perpendicular to the c axis. N—H···I interactions are shown as dashed lines and the electrostatic N^+···I^- interactions as dotted lines. Colour key: purple = I, blue = N, gray = C, orange = H.

4-Cyanoanilinium iodide

Crystal data

C7H7N2^+·I^−	Dx = 1.993 Mg m^−3
Mr = 246.05	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4/nmm	Cell parameters from 8495 reflections
Hall symbol: -P 4a 2a	θ = 2.5–29.1°
a = 4.9930 (4) Å	µ = 3.83 mm^−1
c = 16.445 (2) Å	T = 100 K
V = 409.98 (8) Å^3	Plate, colourless
Z = 2	0.26 × 0.20 × 0.05 mm
F(000) = 232

Data collection

Bruker SMART APEX CCD diffractometer	382 independent reflections
Radiation source: fine–focus sealed tube	381 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
ϕ and ω scans	θmax = 29.1°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 2009)	h = −6→6
Tmin = 0.362, Tmax = 0.844	k = −6→6
7082 measured reflections	l = −22→22

Refinement

Refinement on F^2	Primary atom site location: heavy atom
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.012	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.029	H-atom parameters constrained
S = 1.14	w = 1/[σ^2(Fo^2) + (0.0165P)^2 + 0.1447P] where P = (Fo^2 + 2Fc^2)/3
382 reflections	(Δ/σ)max = 0.002
31 parameters	Δρmax = 0.46 e Å^−3
0 restraints	Δρmin = −0.56 e Å^−3

Special details

Experimental. The diffraction data were obtained from 3 sets of 400 frames, each of width 0.5° in ω, colllected at ϕ = 0.00°, 90.00° and 180.00° and 2 sets of 800 frames, each of width 0.45° in ϕ, collected at ω = -30.00° and 210.00°. The scan time was 10 sec/frame.

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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	Occ. (<1)
I1	0.7500	0.7500	0.588552 (10)	0.01472 (8)
N1	0.2500	0.2500	0.62508 (16)	0.0199 (5)
H1	0.3662	0.3662	0.6057	0.024*	0.25
H1A	0.0887	0.2904	0.6073	0.024*	0.125
H1B	0.2904	0.0887	0.6073	0.024*	0.125
N2	0.2500	0.2500	1.03941 (17)	0.0226 (6)
C1	0.2500	0.2500	0.71467 (18)	0.0139 (5)
C2	0.4934 (6)	0.2500	0.75539 (17)	0.0174 (5)	0.50
H2	0.6576	0.2500	0.7262	0.021*	0.50
C3	0.4936 (6)	0.2500	0.84022 (16)	0.0171 (5)	0.50
H3	0.6583	0.2500	0.8692	0.020*	0.50
C4	0.2500	0.2500	0.88189 (18)	0.0143 (5)
C5	0.2500	0.2500	0.97006 (19)	0.0174 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.01513 (9)	0.01513 (9)	0.01392 (11)	0.000	0.000	0.000
N1	0.0236 (8)	0.0236 (8)	0.0126 (11)	0.000	0.000	0.000
N2	0.0252 (9)	0.0252 (9)	0.0174 (12)	0.000	0.000	0.000
C1	0.0129 (8)	0.0129 (8)	0.0158 (12)	0.000	0.000	0.000
C2	0.0132 (12)	0.0225 (14)	0.0163 (11)	0.000	0.0020 (10)	0.000
C3	0.0129 (12)	0.0226 (13)	0.0157 (11)	0.000	−0.0022 (11)	0.000
C4	0.0146 (8)	0.0146 (8)	0.0136 (13)	0.000	0.000	0.000
C5	0.0161 (9)	0.0161 (9)	0.0200 (14)	0.000	0.000	0.000

Geometric parameters (Å, º)

N1—C1	1.473 (4)	C2—C3	1.395 (4)
N1—H1	0.8800	C2—H2	0.9500
N1—H1A	0.8800	C3—C4	1.396 (3)
N1—H1B	0.8800	C3—H3	0.9500
N2—C5	1.141 (4)	C4—C3^i	1.396 (3)
C1—C2^i	1.388 (3)	C4—C5	1.450 (4)
C1—C2	1.388 (3)
C1—N1—H1	111.2	C1—C2—H2	120.8
C1—N1—H1A	109.4	C3—C2—H2	120.3
H1—N1—H1A	109.4	C2—C3—C4	119.3 (3)
C1—N1—H1B	109.4	C2—C3—H3	120.1
H1—N1—H1B	109.4	C4—C3—H3	120.5
H1A—N1—H1B	108.0	C3^i—C4—C3	121.2 (3)
C2^i—C1—C2	122.3 (3)	C3^i—C4—C5	119.39 (15)
C2^i—C1—N1	118.85 (16)	C3—C4—C5	119.39 (15)
C2—C1—N1	118.85 (16)	N2—C5—C4	180.000 (1)
C1—C2—C3	118.9 (3)
C2^i—C1—C2—C3	0.000 (2)	C1—C2—C3—C4	0.000 (2)
N1—C1—C2—C3	180.000 (1)	C2—C3—C4—C5	180.000 (1)

Symmetry code: (i) −x+1/2, −y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···I1	0.88	2.72	3.5813 (5)	165
N1—H1A···I1^ii	0.88	2.87	3.5813 (5)	139
N1—H1B···I1^iii	0.88	2.87	3.5813 (5)	139

Symmetry codes: (ii) x−1, y, z; (iii) x, y−1, z.