N¹,N⁴-Bis(2-thienylmethyl­ene)cyclo­hexane-1,4-di­amine

The title compound, C₁₆H₁₈N₂S₂, lies about an inversion center with only half of the mol­ecule in the asymmetric unit. The cyclo­hexane ring adopts a chair conformation, and the terminal thio­phene rings are in a transoid orientation, with an S⋯S separation between the two terminal 2-thio­phene rings of 11.6733 (9) Å.

Related literature

For a general introduction to coordination polymers, see: Batten et al. (2009); Perry et al. (2009); Robin & Fromm (2006). For structurally related compounds, see: Yun et al. (2009). For related linking ligands containing terminal thio­phene rings, see: Lee & Lee (2007); Huh et al. (2008); Kim & Lee (2008).

Experimental

Crystal data

• C₁₆H₁₈N₂S₂

• M_r = 302.44

• Monoclinic, P 2₁ /n

• a = 6.2173 (4) Å

• b = 7.4999 (5) Å

• c = 17.1289 (12) Å

• β = 97.047 (3)°

• V = 792.67 (9) ų

• Z = 2

• Mo Kα radiation

• μ = 0.33 mm⁻¹

• T = 296 K

• 0.46 × 0.24 × 0.20 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.864, T_max = 0.937

• 9045 measured reflections

• 1889 independent reflections

• 1590 reflections with I > 2σ(I)

• R_int = 0.022

Refinement

• R[F² > 2σ(F²)] = 0.032

• wR(F²) = 0.089

• S = 1.02

• 1889 reflections

• 127 parameters

• All H-atom parameters refined

• Δρ_max = 0.19 e Å⁻³

• Δρ_min = −0.18 e Å⁻³

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); 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

Design and construction of coordination polymers (or metal–organic frameworks, MOFs) are currently under intensive study due to their desirable applications in catalysis, nonlinear optical activity, spin crossover, luminescence, long-range magnetism, adsorption–desorption, and gas storage (Batten et al., 2009; Perry IV et al., 2009; Robin & Fromm, 2006). In preparing such polymers, appropriate linking ligands play a fundamental role. We have continually reported long bis(pyridine)-, bis(furan)-, bis(thiophene)-, and (pyridine–amine)-type linking ligands and their coordination polymers (Yun et al. 2009). As an extension to our ongoing study of novel linking ligands and their coordination polymers, we have prepared a long, potential linking ligand containing an intervening cyclohexane ring with two terminal thiophene rings.

The molecular structure of the title compound (Fig. 1) contains an intervening cyclohexane ring between two iminethiophene (—N═CH—2-thiophene) fragments. The cyclohexane ring fragment adopts a chair conformation. The imine fragments occupy the equatorial sites of the cyclohexane ring and are trans with respect to each other. The terminal thiophene rings also adopt an overall transoid conformation. The S···S separation between the two terminal 2-thiophene rings is 11.6733 (9) Å. Several related linking ligands containing terminal thiophene rings were previously employed to obtain coordination networks: (2-thiophene)—CH═N—N═CH—(2-thiophene) (Lee & Lee, 2007; Huh et al., 2008) and (3-thiophene)—CH═N—N═CH—(3-thiophene) (Kim & Lee, 2008).

Related literature

For a general introduction, see: Batten et al. (2009); Perry et al. (2009); Robin & Fromm (2006). For structurally related compounds, see: Yun et al. (2009). For related linking ligands containing terminal thiophene rings, see: Lee & Lee (2007); Huh et al. (2008); Kim & Lee (2008).

S2. Experimental

At room temperature, trans-1,4-diaminocyclohexane (1.0 g, 8.76 mmol) was added to 2-thiophene carboxaldehyde (1.72 ml, 18.72 mmol) in 80 ml methanol. After adding dichloromethane (50 ml) and three drops of formic acid, the mixture was stirred for 15 h, and then the solvent was removed under vacuum. The resulting solid was extracted with dichloromethane (150 ml) and washed with water (30 ml × 3). The organic phase was dried over MgSO₄ and then filtered. All the solvent was removed to give white crude solid, which was recrystallized from dichloromethane/hexane to give colorless crystals of the title compound suitable for X-ray crystallographic study (2.05 g, 6.78 mmol, 77%). mp: 511–513 K.

S3. Refinement

All H atoms were located from difference maps and refined isotropically.

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); 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. Molecular structure of the title compound showing 50% probability displacement ellipsoids. Symmetry code for the atoms with A in their labels: -x+2, -y+2, -z+2.

N¹,N⁴-Bis(2-thienylmethylene)cyclohexane-1,4-diamine

Crystal data

C16H18N2S2	F(000) = 320
Mr = 302.44	Dx = 1.267 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 5365 reflections
a = 6.2173 (4) Å	θ = 2.4–28.2°
b = 7.4999 (5) Å	µ = 0.33 mm^−1
c = 17.1289 (12) Å	T = 296 K
β = 97.047 (3)°	Block, colourless
V = 792.67 (9) Å^3	0.46 × 0.24 × 0.20 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	1889 independent reflections
Radiation source: sealed tube	1590 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ϕ and ω scans	θmax = 28.3°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→8
Tmin = 0.864, Tmax = 0.937	k = −8→9
9045 measured reflections	l = −22→19

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.089	All H-atom parameters refined
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0484P)^2 + 0.1406P] where P = (Fo^2 + 2Fc^2)/3
1889 reflections	(Δ/σ)max = 0.001
127 parameters	Δρmax = 0.19 e Å^−3
0 restraints	Δρmin = −0.18 e Å^−3

Special details

Experimental. IR (KBr, cm^-1): 3443 (w), 3103 (w), 2923 (m), 2852 (w), 1626 (s), 1430 (m), 1306 (w), 1210 (m), 1084 (m), 944 (m), 847 (m), 730 (s), 498 (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	0.65706 (5)	0.42717 (5)	0.78995 (2)	0.04947 (14)
N1	0.78346 (18)	0.71526 (15)	0.91441 (7)	0.0458 (3)
C1	0.4495 (3)	0.2897 (2)	0.75469 (10)	0.0554 (4)
C2	0.2791 (3)	0.3032 (2)	0.79591 (10)	0.0575 (4)
C3	0.3138 (2)	0.42688 (19)	0.85814 (9)	0.0488 (3)
C4	0.51420 (19)	0.50601 (18)	0.86246 (7)	0.0396 (3)
C5	0.6024 (2)	0.64140 (18)	0.91770 (7)	0.0412 (3)
C6	0.8511 (2)	0.85271 (18)	0.97279 (8)	0.0430 (3)
C7	0.8308 (3)	1.0366 (2)	0.93470 (10)	0.0527 (4)
C8	1.0844 (2)	0.8189 (2)	1.00708 (10)	0.0516 (3)
H1	0.465 (3)	0.218 (2)	0.7107 (11)	0.069 (5)*
H2	0.157 (3)	0.239 (3)	0.7840 (10)	0.070 (5)*
H3	0.218 (2)	0.4550 (19)	0.8910 (10)	0.051 (4)*
H5	0.518 (2)	0.6691 (19)	0.9570 (9)	0.050 (4)*
H6	0.761 (2)	0.847 (2)	1.0152 (9)	0.053 (4)*
H7A	0.687 (3)	1.058 (2)	0.9140 (12)	0.074 (6)*
H7B	0.909 (3)	1.037 (2)	0.8896 (11)	0.061 (5)*
H8B	1.176 (3)	0.821 (2)	0.9662 (10)	0.056 (4)*
H8A	1.104 (3)	0.705 (2)	1.0311 (10)	0.059 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0449 (2)	0.0531 (2)	0.0512 (2)	−0.00126 (14)	0.00905 (15)	−0.00792 (15)
N1	0.0473 (6)	0.0465 (6)	0.0443 (6)	−0.0070 (5)	0.0087 (5)	−0.0088 (5)
C1	0.0617 (9)	0.0484 (8)	0.0545 (8)	−0.0023 (7)	0.0005 (7)	−0.0112 (7)
C2	0.0523 (8)	0.0552 (9)	0.0631 (9)	−0.0150 (7)	−0.0003 (7)	−0.0052 (7)
C3	0.0445 (7)	0.0532 (8)	0.0491 (7)	−0.0066 (6)	0.0077 (6)	−0.0008 (6)
C4	0.0400 (6)	0.0389 (6)	0.0393 (6)	0.0006 (5)	0.0035 (5)	0.0025 (5)
C5	0.0418 (6)	0.0428 (7)	0.0389 (6)	0.0016 (5)	0.0051 (5)	0.0000 (5)
C6	0.0450 (7)	0.0441 (7)	0.0407 (6)	−0.0041 (5)	0.0084 (5)	−0.0076 (6)
C7	0.0531 (8)	0.0492 (8)	0.0518 (8)	0.0023 (6)	−0.0091 (7)	−0.0035 (6)
C8	0.0544 (8)	0.0397 (8)	0.0584 (9)	0.0050 (6)	−0.0030 (7)	−0.0044 (6)

Geometric parameters (Å, º)

S1—C1	1.7038 (16)	C5—H5	0.928 (15)
S1—C4	1.7181 (13)	C6—C8	1.518 (2)
N1—C5	1.2619 (16)	C6—C7	1.524 (2)
N1—C6	1.4616 (16)	C6—H6	0.971 (16)
C1—C2	1.347 (2)	C7—C8^i	1.522 (2)
C1—H1	0.941 (18)	C7—H7A	0.94 (2)
C2—C3	1.410 (2)	C7—H7B	0.960 (19)
C2—H2	0.900 (18)	C8—C7^i	1.522 (2)
C3—C4	1.3736 (18)	C8—H8B	0.954 (16)
C3—H3	0.894 (15)	C8—H8A	0.951 (17)
C4—C5	1.4492 (19)
C1—S1—C4	91.62 (7)	N1—C6—C7	110.09 (11)
C5—N1—C6	117.53 (11)	C8—C6—C7	109.96 (12)
C2—C1—S1	112.26 (12)	N1—C6—H6	109.6 (9)
C2—C1—H1	129.0 (11)	C8—C6—H6	108.2 (9)
S1—C1—H1	118.7 (11)	C7—C6—H6	109.8 (9)
C1—C2—C3	112.85 (14)	C8^i—C7—C6	111.09 (12)
C1—C2—H2	122.3 (11)	C8^i—C7—H7A	111.4 (11)
C3—C2—H2	124.8 (11)	C6—C7—H7A	110.0 (11)
C4—C3—C2	112.27 (13)	C8^i—C7—H7B	111.0 (11)
C4—C3—H3	122.4 (10)	C6—C7—H7B	108.7 (10)
C2—C3—H3	125.3 (10)	H7A—C7—H7B	104.5 (15)
C3—C4—C5	127.31 (12)	C6—C8—C7^i	111.86 (12)
C3—C4—S1	110.99 (11)	C6—C8—H8B	109.9 (10)
C5—C4—S1	121.69 (9)	C7^i—C8—H8B	106.4 (10)
N1—C5—C4	123.14 (12)	C6—C8—H8A	112.4 (10)
N1—C5—H5	121.5 (10)	C7^i—C8—H8A	110.0 (10)
C4—C5—H5	115.3 (10)	H8B—C8—H8A	106.0 (13)
N1—C6—C8	109.16 (11)

Symmetry code: (i) −x+2, −y+2, −z+2.