2,2′-Bi­thio­phene-3,3′-dicarbo­nitrile

The complete mol­ecule of the title compound, C₁₀H₄N₂S₂, is generated by an inversion center situated at the mid-point of the bridging C—C bond. The bithio­phene ring system is planar [maximum deviation = 0.003 (2) Å] and the central C—C bond length is 1.450 (2) Å. There are no significant inter­molecular inter­actions in the crystal structure, which is stabilized by van der Waals inter­actions.

Related literature

For the importance of bithio­phene derivatives, see: Katz et al. (1995). For their applications, see: Deng et al. (2011); Thomas et al. (2008). For background to the title compound, see: Demanze et al. (1996); Pletnev et al. (2002); For related structures, see: Benedict et al. (2004); Huang & Li (2011); Pelletier et al. (1995); Li & Li (2009); Teh et al. (2012). For thio­phene C—S bond lengths, see: Howie & Wardell (2006). For the normal bonding picture for bithio­phene, see: Khan et al. (2004).

Experimental

Crystal data

• C₁₀H₄N₂S₂

• M_r = 216.27

• Monoclinic, P 2₁ /c

• a = 3.9084 (1) Å

• b = 9.8832 (4) Å

• c = 12.0091 (5) Å

• β = 93.900 (2)°

• V = 462.81 (3) ų

• Z = 2

• Mo Kα radiation

• μ = 0.53 mm⁻¹

• T = 293 K

• 0.30 × 0.20 × 0.20 mm

Data collection

• Bruker Kappa APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2004) T_min = 0.881, T_max = 0.900

• 6689 measured reflections

• 1802 independent reflections

• 1409 reflections with I > 2σ(I)

• R_int = 0.019

Refinement

• R[F² > 2σ(F²)] = 0.034

• wR(F²) = 0.105

• S = 1.05

• 1802 reflections

• 64 parameters

• H-atom parameters constrained

• Δρ_max = 0.36 e Å⁻³

• Δρ_min = −0.20 e Å⁻³

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT (Bruker, 2004); data reduction: SAINT and XPREP (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009).

Supporting information

S1. Comment

Bithiophene derivatives are important compounds in the synthesis of oligothiophenes and polythiophenes which have attracted attention as materials showing interesting characteristics as conducting, nonlinear optical (NLO), and liquid crystalline materials (Katz et al., 1995). Oligothiophenes and their derivatives are useful precursors for the construction of organic materials suitable for application in electronic devices (Deng et al., 2011; Thomas et al., 2008) and the presence of an electron-withdrawing cyano group may offer a route to tune the electronic properties of the resulting materials. Our interest in these derivatives has led us to prepare the title compound which is known in the literature (Pletnev et al., 2002; Demanze et al., 1996) but was obtained as a side product during the attempted synthesis of other derivatives. We herein report on the direct synthesis and the crystal structure of the title compound.

The asymmetric unit of the title compound, comprises half a molecule with the full molecule generated by a crystallographic centre of inversion (Fig. 1). The bithiophene unit is planar to within 0.003 (2) Å. Within the bithiophene unit, the C1—C2 and C3—C4 bond-lengths [1.3838 (16) and 1.3487 (19) Å, respectively] are significantly shorter than bond C2—C3, 1.4173 (19) Å. This is consistent with the normal bonding picture for bithiophene (Khan et al., 2004).

One feature of the molecule is the difference between the S1—C1 and S1—C4 bond lengths [1.724 (1) and 1.700 (1) Å, respectively]. Howie and Wardell (2006) have noted a similar disparity in the S—C bond lengths. This generally agrees with those values found for related structures, such as 2,2'-[2,5-Bis(hexyloxy)-1,4-phenylene]-dithiophene (Teh et al., 2012) and 3,3',5,5'-Tetrabromo-2,2'-bithiophene (Li & Li, 2009).

The carbonitrile chain is almost linear, with the N1-C5-C2 bond angle being 177.43 (15)°. The geometric parameters are comparable with those observed in the related structures 3,3'-Bis(octyloxy)-2,2'-bithiophene at 195 K (Pelletier et al., 1995), 2,2'-(3,3'-Dihexyl-2,2'-bithiophene-5,5'-diyl) bis(4,4,5,5-tetramethyl-1,3,2-dioxa-borolane) [Huang & Li, 2011] and 3,3'-Didecyl-5,5,-bis(4-phenylquinolin-2-yl)-2,2'-bithienyl (Benedict et al., 2004).

There are no significant hydrogen-bonding interactions in the crystal structure, which is stabilized by van der Waals interactions.

Related literature

For the importance of bithiophene derivatives, see: Katz et al. (1995). For their applications, see: Deng et al. (2011); Thomas et al. (2008). For background to the title compound, see: Demanze et al. (1996); Pletnev et al. (2002); For related structures, see: Benedict et al. (2004); Huang & Li (2011); Pelletier et al. (1995); Li & Li (2009); Teh et al. (2012). For thiophene C—S bond lengths, see: Howie & Wardell (2006). For the normal bonding picture for bithiophene, see: Khan et al. (2004).

S2. Experimental

Copper(I) cyanide (5.17 g, 57.72 mmol) was added to a solution of 3,3'-dibromo-2, 2'-bithiophene (6.23 g, 19.24 mmol) in 50 ml of DMF. This mixture was heated at 423 K for 32 h under nitrogen atmosphere. After cooling to room temperature, 50 ml of aqueous ammonia solution was added and allowed to stir for 4 h at room temperature. It was extracted with ethyl acetate and the combined organic layer washed with 3× 100 ml of water and dried over anhydrous sodium sulfate. On vacuum evaporation it produced a crude solid which was purified by column chromatography on silica gel using 4:1 mixture of hexanes and ethylacetate as eluant, to give a pale yellow solid; Yield 1.66 g (40%). Yellow block-like crystals were grown from an ethylacetate/hexane (1:4) mixture (M.p. 477 K). Spectroscopic data for the title compound are given in the archived CIF.

S3. Refinement

All the H atoms were positioned geometrically and refined using a riding model: C—H = 0.93 Å with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 and SAINT (Bruker, 2004); data reduction: SAINT and XPREP (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009).

Figures

Fig. 1. The molecular structure of the title molecule showing the atom numbering. the displacement ellipsoids are drawn at the 50% probability level.

2,2'-Bithiophene-3,3'-dicarbonitrile

Crystal data

C10H4N2S2	Z = 2
Mr = 216.27	F(000) = 220
Monoclinic, P21/c	Dx = 1.552 Mg m^−3
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 3.9084 (1) Å	θ = 2.7–33.5°
b = 9.8832 (4) Å	µ = 0.53 mm^−1
c = 12.0091 (5) Å	T = 293 K
β = 93.900 (2)°	Block, yellow
V = 462.81 (3) Å^3	0.30 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD diffractometer	1802 independent reflections
Radiation source: fine-focus sealed tube	1409 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.019
ω and φ scan	θmax = 33.5°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −5→5
Tmin = 0.881, Tmax = 0.900	k = −15→14
6689 measured reflections	l = −18→18

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.105	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0536P)^2 + 0.0819P] where P = (Fo^2 + 2Fc^2)/3
1802 reflections	(Δ/σ)max = 0.001
64 parameters	Δρmax = 0.36 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

Special details

Experimental. Spectroscopic data for the title compund:

IR (KBr, cm^-1) 2221.0 (ν C≡N); ¹H NMR (CDCl3, 500.13 MHz) δ 7.37 (d, J = 5.36 Hz, 2H),7.53 (d, J = 5.36 Hz, 2H); ¹³C NMR (CDCl3, 125.75 MHz); δ 110.0, 114.5, 128.3, 130.4, 141.0 p.p.m.

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
S1	0.28852 (8)	0.68019 (3)	0.41382 (2)	0.04106 (12)
C1	0.4855 (3)	0.57190 (12)	0.51077 (9)	0.0320 (2)
C2	0.6002 (3)	0.64524 (13)	0.60413 (9)	0.0367 (2)
C5	0.7804 (4)	0.59005 (15)	0.70133 (10)	0.0439 (3)
C4	0.3580 (4)	0.81738 (13)	0.49772 (12)	0.0475 (3)
H4	0.2877	0.9046	0.4781	0.057*
C3	0.5265 (4)	0.78545 (14)	0.59594 (11)	0.0458 (3)
H3	0.5872	0.8480	0.6517	0.055*
N1	0.9252 (4)	0.55103 (16)	0.77997 (11)	0.0630 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0472 (2)	0.03822 (18)	0.03623 (18)	0.00130 (11)	−0.00859 (12)	0.00367 (11)
C1	0.0314 (4)	0.0354 (5)	0.0287 (5)	−0.0021 (4)	−0.0009 (3)	0.0025 (4)
C2	0.0394 (6)	0.0387 (6)	0.0313 (5)	−0.0030 (5)	−0.0020 (4)	−0.0006 (4)
C5	0.0518 (7)	0.0431 (6)	0.0354 (6)	−0.0063 (5)	−0.0073 (5)	−0.0029 (5)
C4	0.0567 (8)	0.0339 (6)	0.0507 (7)	0.0022 (5)	−0.0053 (6)	0.0005 (5)
C3	0.0554 (8)	0.0380 (6)	0.0429 (7)	−0.0015 (5)	−0.0044 (5)	−0.0048 (5)
N1	0.0802 (10)	0.0599 (8)	0.0454 (6)	−0.0049 (7)	−0.0218 (6)	0.0021 (6)

Geometric parameters (Å, º)

S1—C4	1.7000 (14)	C2—C5	1.4298 (16)
S1—C1	1.7240 (11)	C5—N1	1.1351 (17)
C1—C2	1.3838 (16)	C4—C3	1.3487 (19)
C1—C1^i	1.450 (2)	C4—H4	0.9300
C2—C3	1.4173 (19)	C3—H3	0.9300
C4—S1—C1	92.80 (6)	N1—C5—C2	177.43 (15)
C2—C1—C1^i	129.27 (13)	C3—C4—S1	112.37 (10)
C2—C1—S1	109.09 (9)	C3—C4—H4	123.8
C1^i—C1—S1	121.63 (11)	S1—C4—H4	123.8
C1—C2—C3	113.76 (11)	C4—C3—C2	111.98 (12)
C1—C2—C5	125.17 (12)	C4—C3—H3	124.0
C3—C2—C5	121.07 (11)	C2—C3—H3	124.0

Symmetry code: (i) −x+1, −y+1, −z+1.