4,4'-[Butane-1,4-diylbis(nitrilo-methyl-idyne)]dibenzonitrile.

The title Schiff base compound, C(20)H(18)N(4), lies across a crystallographic inversion centre and adopts E configurations with respect to the C=N bonds. The asymmetric unit of the compound is composed of one half-mol-ecule. The imino group is coplanar with the benzene ring. Within the mol-ecule, the planar units are parallel but extend in opposite directions from the methyl-ene bridge. In the crystal structure, neighbouring mol-ecules are linked together by weak inter-molecular C-H⋯N hydrogen bonds involving the cyano N atoms. These form ten-membered rings, generating R(2) (2)(10) ring motifs, and link the mol-ecules along the c axis.

Related literature

For bond-length data, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For information on Schiff base ligands, their complexes and applications, see, for example: Fun, Kargar & Kia (2008 ▶); Fun, Kia & Kargar (2008 ▶); Fun & Kia (2008a ▶,b ▶); Calligaris & Randaccio (1987 ▶); Casellato & Vigato (1977 ▶).

Experimental

Crystal data

C20H18N4

M = 314.38

Monoclinic,

a = 4.9720 (2) Å

b = 10.5047 (5) Å

c = 16.0315 (6) Å

β = 97.220 (3)°

V = 830.68 (6) Å3

Z = 2

Mo Kα radiation

μ = 0.08 mm−1

T = 100.0 (1) K

0.52 × 0.33 × 0.13 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer

Absorption correction: multi-scan (; Bruker, 2005 ▶) T min = 0.942, T max = 0.990

10382 measured reflections

2603 independent reflections

2035 reflections with I > 2σ(I)

R int = 0.027

Refinement

R[F 2 > 2σ(F 2)] = 0.046

wR(F 2) = 0.143

S = 1.11

2603 reflections

145 parameters

All H-atom parameters refined

Δρmax = 0.31 e Å−3

Δρmin = −0.20 e Å−3

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005 ▶); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680802744X/sj2534sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802744X/sj2534Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C20H18N4	F000 = 332
Mr = 314.38	Dx = 1.257 Mg m−3
Monoclinic, P21/n	Mo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2704 reflections
a = 4.9720 (2) Å	θ = 3.2–30.8º
b = 10.5047 (5) Å	µ = 0.08 mm−1
c = 16.0315 (6) Å	T = 100.0 (1) K
β = 97.220 (3)º	Block, colourless
V = 830.68 (6) Å3	0.52 × 0.33 × 0.13 mm
Z = 2

Bruker SMART APEXII CCD area-detector diffractometer	2603 independent reflections
Radiation source: fine-focus sealed tube	2035 reflections with I > 2σ(I)
Monochromator: graphite	Rint = 0.027
T = 100.0(1) K	θmax = 30.9º
φ and ω scans	θmin = 2.3º
Absorption correction: multi-scan(SADABS; Bruker, 2005)	h = −7→7
Tmin = 0.942, Tmax = 0.990	k = −12→15
10382 measured reflections	l = −23→20

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046	All H-atom parameters refined
wR(F2) = 0.143	w = 1/[σ2(Fo2) + (0.08P)2 + 0.042P] where P = (Fo2 + 2Fc2)/3
S = 1.12	(Δ/σ)max = 0.001
2603 reflections	Δρmax = 0.31 e Å−3
145 parameters	Δρmin = −0.20 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

	x	y	z	Uiso*/Ueq
N1	0.31548 (17)	0.07369 (8)	0.67193 (5)	0.0242 (2)
N2	−0.5866 (2)	0.17550 (9)	1.01544 (6)	0.0364 (3)
C1	0.0130 (2)	0.06350 (9)	0.81305 (6)	0.0255 (2)
C2	−0.1490 (2)	0.06318 (10)	0.87727 (6)	0.0269 (2)
C3	−0.3002 (2)	0.17138 (9)	0.89127 (6)	0.0240 (2)
C4	−0.2917 (2)	0.27859 (10)	0.84069 (6)	0.0260 (2)
C5	−0.1254 (2)	0.27847 (10)	0.77740 (6)	0.0246 (2)
C6	0.02661 (18)	0.17141 (9)	0.76284 (6)	0.0213 (2)
C7	0.20222 (19)	0.17330 (9)	0.69517 (6)	0.0218 (2)
C8	0.49150 (19)	0.08750 (10)	0.60619 (6)	0.0245 (2)
C9	0.39698 (18)	0.00237 (9)	0.53129 (6)	0.0226 (2)
C10	−0.4614 (2)	0.17317 (10)	0.95980 (6)	0.0276 (2)
H1	0.121 (3)	−0.0110 (13)	0.8041 (8)	0.033 (3)*
H2	−0.153 (3)	−0.0091 (13)	0.9122 (8)	0.035 (3)*
H4	−0.401 (3)	0.3560 (13)	0.8497 (8)	0.032 (3)*
H5	−0.116 (2)	0.3552 (12)	0.7446 (8)	0.033 (3)*
H7	0.224 (2)	0.2575 (12)	0.6706 (8)	0.028 (3)*
H8A	0.502 (2)	0.1786 (11)	0.5893 (8)	0.028 (3)*
H8B	0.678 (2)	0.0626 (11)	0.6313 (7)	0.025 (3)*
H9A	0.222 (2)	0.0346 (11)	0.5017 (7)	0.024 (3)*
H9B	0.363 (2)	−0.0864 (12)	0.5502 (8)	0.029 (3)*

	U11	U22	U33	U12	U13	U23
N1	0.0259 (4)	0.0289 (4)	0.0189 (4)	−0.0028 (3)	0.0071 (3)	−0.0027 (3)
N2	0.0469 (6)	0.0336 (5)	0.0326 (5)	−0.0050 (4)	0.0199 (4)	−0.0056 (4)
C1	0.0297 (5)	0.0240 (5)	0.0242 (5)	0.0005 (4)	0.0086 (4)	−0.0012 (4)
C2	0.0333 (5)	0.0267 (5)	0.0225 (5)	−0.0032 (4)	0.0102 (4)	0.0004 (4)
C3	0.0246 (5)	0.0285 (5)	0.0199 (5)	−0.0065 (4)	0.0067 (3)	−0.0060 (3)
C4	0.0277 (5)	0.0265 (5)	0.0248 (5)	−0.0017 (4)	0.0079 (4)	−0.0046 (4)
C5	0.0287 (5)	0.0241 (5)	0.0221 (5)	−0.0022 (4)	0.0073 (4)	−0.0009 (3)
C6	0.0213 (4)	0.0247 (5)	0.0183 (4)	−0.0041 (3)	0.0041 (3)	−0.0040 (3)
C7	0.0231 (4)	0.0248 (5)	0.0182 (4)	−0.0047 (3)	0.0045 (3)	−0.0018 (3)
C8	0.0229 (5)	0.0321 (5)	0.0200 (5)	−0.0042 (4)	0.0080 (3)	−0.0036 (4)
C9	0.0189 (4)	0.0307 (5)	0.0189 (4)	−0.0028 (4)	0.0052 (3)	−0.0036 (4)
C10	0.0325 (5)	0.0267 (5)	0.0252 (5)	−0.0055 (4)	0.0104 (4)	−0.0054 (4)

N1—C7	1.2663 (13)	C4—H4	0.999 (13)
N1—C8	1.4594 (12)	C5—C6	1.3910 (14)
N2—C10	1.1505 (13)	C5—H5	0.967 (13)
C1—C2	1.3845 (14)	C6—C7	1.4757 (13)
C1—C6	1.3969 (14)	C7—H7	0.979 (13)
C1—H1	0.971 (13)	C8—C9	1.5233 (13)
C2—C3	1.3963 (15)	C8—H8A	0.998 (12)
C2—H2	0.946 (14)	C8—H8B	0.996 (12)
C3—C4	1.3916 (14)	C9—C9i	1.5220 (18)
C3—C10	1.4392 (14)	C9—H9A	0.997 (11)
C4—C5	1.3869 (14)	C9—H9B	1.002 (12)
C7—N1—C8	117.36 (8)	C1—C6—C7	120.70 (8)
C2—C1—C6	120.36 (9)	N1—C7—C6	122.09 (9)
C2—C1—H1	119.5 (7)	N1—C7—H7	123.5 (7)
C6—C1—H1	120.1 (7)	C6—C7—H7	114.4 (7)
C1—C2—C3	119.52 (9)	N1—C8—C9	110.94 (8)
C1—C2—H2	120.1 (8)	N1—C8—H8A	110.5 (7)
C3—C2—H2	120.3 (8)	C9—C8—H8A	111.8 (7)
C4—C3—C2	120.58 (9)	N1—C8—H8B	107.0 (7)
C4—C3—C10	119.66 (9)	C9—C8—H8B	110.1 (7)
C2—C3—C10	119.75 (9)	H8A—C8—H8B	106.4 (10)
C5—C4—C3	119.35 (9)	C9i—C9—C8	111.85 (9)
C5—C4—H4	119.5 (7)	C9i—C9—H9A	108.5 (6)
C3—C4—H4	121.2 (7)	C8—C9—H9A	109.9 (7)
C4—C5—C6	120.66 (9)	C9i—C9—H9B	108.8 (7)
C4—C5—H5	118.1 (8)	C8—C9—H9B	110.8 (7)
C6—C5—H5	121.2 (8)	H9A—C9—H9B	106.8 (10)
C5—C6—C1	119.52 (9)	N2—C10—C3	178.83 (11)
C5—C6—C7	119.78 (8)
C6—C1—C2—C3	0.35 (15)	C2—C1—C6—C7	178.98 (9)
C1—C2—C3—C4	0.77 (15)	C8—N1—C7—C6	−178.16 (8)
C1—C2—C3—C10	−177.82 (9)	C5—C6—C7—N1	−170.25 (9)
C2—C3—C4—C5	−1.76 (15)	C1—C6—C7—N1	10.32 (14)
C10—C3—C4—C5	176.82 (9)	C7—N1—C8—C9	−122.71 (9)
C3—C4—C5—C6	1.66 (14)	N1—C8—C9—C9i	−170.18 (10)
C4—C5—C6—C1	−0.57 (15)	C4—C3—C10—N2	−87 (6)
C4—C5—C6—C7	180.00 (8)	C2—C3—C10—N2	92 (6)
C2—C1—C6—C5	−0.45 (15)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···N2ii	0.945 (13)	2.541 (14)	3.3973 (14)	150.8 (12)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯N2i	0.945 (13)	2.541 (14)	3.3973 (14)	150.8 (12)

Symmetry code: (i) .