p-Iso­cyano­benzo­nitrile

p-Di­cyano­benzene and p-diiso­cyano­benzene are not isomorphous. The title compound, C₈H₄N₂, is isomorphous with p-di­cyano­benzene. The mol­ecule lies on a center of symmetry and is end-for-end disordered. The bond lengths and angles lie within normal ranges, but the precise values are obscured by the disorder.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.049
• wR factor = 0.133
• Data-to-parameter ratio = 13.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

p-isocyanobenzonitrile

Crystal data

C8H4N2	Z = 1
Mr = 128.13	F(000) = 66
Triclinic, P1	Dx = 1.279 Mg m^−3
a = 3.7923 (11) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.4680 (18) Å	Cell parameters from 1186 reflections
c = 7.504 (2) Å	θ = 3.0–27.5°
α = 113.099 (10)°	µ = 0.08 mm^−1
β = 94.412 (10)°	T = 173 K
γ = 97.128 (10)°	Needle, colorless
V = 166.41 (8) Å^3	0.50 × 0.15 × 0.10 mm

Data collection

Siemens SMART area-detector diffractometer	747 independent reflections
Radiation source: fine-focus sealed tube	610 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
ω scans	θmax = 27.5°, θmin = 3.0°
Absorption correction: multi-scan SADABS (Sheldrick, 1996; Blessing, 1995)	h = −4→4
Tmin = 0.97, Tmax = 0.99	k = −8→8
1941 measured reflections	l = −9→9

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.133	All H-atom parameters refined
S = 1.07	w = 1/[σ^2(Fo^2) + (0.079P)^2 + 0.0192P] where P = (Fo^2 + 2Fc^2)/3
747 reflections	(Δ/σ)max = 0.001
54 parameters	Δρmax = 0.22 e Å^−3
0 restraints	Δρmin = −0.21 e Å^−3

Special details

Refinement. Atoms C7(N7) and C8(N8) were assumed to have 50/50 disorder between C and N.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
C1	0.1172 (3)	0.5945 (2)	0.69825 (18)	0.0310 (4)
C2	0.1421 (3)	0.3664 (2)	0.5875 (2)	0.0329 (4)
H2	0.242 (4)	0.281 (2)	0.653 (2)	0.037 (4)*
C3	0.0251 (3)	0.2717 (2)	0.3886 (2)	0.0333 (4)
H3	0.042 (4)	0.113 (3)	0.305 (2)	0.043 (4)*
C7	0.2402 (3)	0.6929 (2)	0.90203 (18)	0.0365 (4)	0.50
N7	0.2402 (3)	0.6929 (2)	0.90203 (18)	0.0365 (4)	0.50
C8	0.3426 (4)	0.7754 (2)	1.0717 (2)	0.0447 (4)	0.50
N8	0.3426 (4)	0.7754 (2)	1.0717 (2)	0.0447 (4)	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0234 (6)	0.0372 (7)	0.0331 (7)	0.0056 (5)	0.0056 (5)	0.0146 (6)
C2	0.0282 (7)	0.0368 (7)	0.0384 (8)	0.0089 (5)	0.0059 (5)	0.0191 (6)
C3	0.0299 (7)	0.0330 (7)	0.0371 (8)	0.0083 (5)	0.0073 (5)	0.0131 (6)
C7	0.0323 (7)	0.0371 (7)	0.0424 (8)	0.0085 (5)	0.0063 (5)	0.0177 (6)
N7	0.0323 (7)	0.0371 (7)	0.0424 (8)	0.0085 (5)	0.0063 (5)	0.0177 (6)
C8	0.0476 (8)	0.0441 (8)	0.0427 (8)	0.0114 (6)	0.0042 (6)	0.0173 (6)
N8	0.0476 (8)	0.0441 (8)	0.0427 (8)	0.0114 (6)	0.0042 (6)	0.0173 (6)

Geometric parameters (Å, º)

C1—C2	1.4004 (19)	C2—H2	0.961 (15)
C1—C3^i	1.4030 (19)	C3—C1^i	1.4030 (19)
C1—C7	1.4192 (17)	C3—H3	0.986 (16)
C2—C3	1.3833 (19)	C7—C8	1.1814 (17)
C2—C1—C3^i	121.27 (12)	C1—C2—H2	118.4 (9)
C2—C1—C7	119.41 (11)	C2—C3—C1^i	119.47 (12)
C3^i—C1—C7	119.32 (11)	C2—C3—H3	121.8 (9)
C3—C2—C1	119.26 (12)	C1^i—C3—H3	118.8 (9)
C3—C2—H2	122.3 (9)	C8—C7—C1	179.82 (12)

Symmetry code: (i) −x, −y+1, −z+1.