1,7-Di­ethyl-4,10-diiso­propyl­tetra­cene

The mol­ecule of the title compound, C₂₈H₃₂, is located on a crystallographic inversion center. The ethyl groups are essentially coplanar with the tetra­cene ring, making a torsion angle of −0.4 (4)°. The isopropyl groups adopt an asymmetric conformation with their terminal methyl groups positioned on opposite sides of the tetra­cene plane [the Me—C—C—C torsion angles are −22.5 (4) and 100.9 (3)°]. In the crystal, the mol­ecules adopt an arrangement without significant π–π inter­actions along the stacking direction (y axis).

Related literature

For applications of tetra­cene derivatives, see: Anthony (2008). For crystallochromy, see: Klebe et al. (1989). For the synthesis, see: Kitamura et al. (2011). For structures of related alkyl-substituted tetra­cene derivatives, see: Kitamura, Abe et al. (2010); Kitamura, Tsukuda et al. (2010).

Experimental

Crystal data

• C₂₈H₃₂

• M_r = 368.54

• Monoclinic, P 2₁ /n

• a = 12.901 (4) Å

• b = 5.057 (2) Å

• c = 16.962 (6) Å

• β = 106.513 (9)°

• V = 1061.0 (7) ų

• Z = 2

• Mo Kα radiation

• μ = 0.06 mm⁻¹

• T = 203 K

• 0.25 × 0.13 × 0.1 mm

Data collection

• Rigaku R-AXIS RAPID IP diffractometer

• 9469 measured reflections

• 2423 independent reflections

• 1318 reflections with I > 2σ(I)

• R_int = 0.083

Refinement

• R[F² > 2σ(F²)] = 0.081

• wR(F²) = 0.282

• S = 1.10

• 2423 reflections

• 130 parameters

• H-atom parameters constrained

• Δρ_max = 0.26 e Å⁻³

• Δρ_min = −0.42 e Å⁻³

Data collection: RAPID-AUTO (Rigaku, 1999); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: PROCESS-AUTO; program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Supporting information

S1. Comment

Tetracene is a promising organic semiconducting molecule for OFETs, OLEDs, and solar cells (Anthony, 2008). In addition, we have recently found that alkyl-substituted tetracenes possess interesting chromophore properties. Depending on the length, shape, and the number of alkyl side chains, the solid-state color of the tetetracenes varies through yellow, orange and red (Kitamura, Abe et al., 2010; Kitamura, Tsukuda et al., 2010). The difference in color can be attributed to crystallochromy (Klebe, et al., 1989), i.e. to a color change caused by different molecular interactions based on different molecular arrangements induced by the substituents. Very recently, we have prepared anti/syn-regioisomeric mixtures of alkyl-substituted tetracenes and reported that the solid-state color of the mixtures changed before and after recrystallization from Et₂O (Kitamura, et al., 2011). To further investigate the effects of alkyl side chains on the solid-state colorations, we have synthesized an anti/syn mixture of ethyl/isopropyl-substituted tetracene (anti isomer – the title compound; syn isomer – 1,10-diethyl-4,7-diisopropyltetracene). The molecular arrangement in the crystal of the anti isomer is shown on Fig. 2.

Related literature

For applications of tetracene derivatives, see: Anthony (2008). For crystallochromy, see: Klebe et al. (1989). For the synthesis, see: Kitamura et al. (2011). For structures of related alkyl-substituted tetracene derivatives, see: Kitamura, Abe et al. (2010); Kitamura, Tsukuda et al. (2010).

S2. Experimental

The anti/syn ethyl/isopropyl-substituted tetracene mixture was prepared as an orange solid (329 mg) according to the method described by Kitamura et al. (2011), except that 2-ethyl-5-isopropyl furan was used. Recrystallization from Et₂O afforded a yellow solid (263 mg). ¹H-NMR: δ 1.51–1.56 (m, 18H), 3.28 (q, J = 7.5 Hz, 4H), 3.92–3.99 (m, 2H), 7.23–7.28 (m, 4H), 8.89 (s, 4H), 8.95 (s, 4H); ¹³C-NMR: δ 14.52, 23.59, 26.63, 28.65, 120.24, 122.75, 122.99, 123.27, 137.81, 142.57; EIMS: m/z (%) 368 (100); Elemental analysis for C₂₈H₃₂: C, 91.25; H, 8.75. Found: C, 91.17; H, 8.89. Single crystals suitable for X-ray analysis were obtained by slow evaporation from Et₂O.

S3. Refinement

All the H atoms were positioned geometrically and refined using a riding model with C—H = 0.94Å and U_iso(H) = 1.2U_eq(C) for aromatic C—H, C—H = 0.99Å and U_iso(H) = 1.2U_eq(C) for CH, and C—H = 0.97Å and U_iso(H) = 1.5U_eq(C) for CH₃. The positions of methyl H atoms were optimized rotationally.

Computing details

Data collection: RAPID-AUTO (Rigaku, 1999); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: PROCESS-AUTO (Rigaku, 1998); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The molecular structure of the title compound, showing the atomic numbering numbering and 30% probability displacement ellipsoids for non-H atoms. Symmetry code: (i) -x, -y + 1, -z.
	Fig. 2. The packing diagram of the title compound. Hydrogen atoms are omitted for clarity.

1,7-Diethyl-4,10-diisopropyltetracene

Crystal data

C28H32	F(000) = 400
Mr = 368.54	Dx = 1.154 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3820 reflections
a = 12.901 (4) Å	θ = 3.3–27.5°
b = 5.057 (2) Å	µ = 0.06 mm^−1
c = 16.962 (6) Å	T = 203 K
β = 106.513 (9)°	Prism, yellow
V = 1061.0 (7) Å^3	0.25 × 0.13 × 0.1 mm
Z = 2

Data collection

Rigaku R-AXIS RAPID IP diffractometer	1318 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.083
Graphite monochromator	θmax = 27.5°, θmin = 3.3°
Detector resolution: 10 pixels mm^-1	h = −16→16
ω scans	k = −6→6
9469 measured reflections	l = −22→22
2423 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.081	H-atom parameters constrained
wR(F^2) = 0.282	w = 1/[σ^2(Fo^2) + (0.1483P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
2423 reflections	Δρmax = 0.26 e Å^−3
130 parameters	Δρmin = −0.42 e Å^−3
0 restraints

Special details

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 > 2σ(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
C1	0.2359 (2)	0.9140 (5)	−0.04992 (16)	0.0445 (7)
C2	0.3434 (2)	0.8926 (5)	−0.01162 (17)	0.0475 (7)
H2	0.3918	1.0027	−0.0286	0.057*
C3	0.3853 (2)	0.7094 (5)	0.05323 (17)	0.0492 (7)
H3	0.4606	0.7005	0.0766	0.059*
C4	0.32137 (19)	0.5464 (5)	0.08311 (16)	0.0436 (7)
C5	0.20585 (18)	0.5603 (5)	0.04493 (15)	0.0418 (7)
C6	0.16283 (19)	0.7463 (4)	−0.02117 (16)	0.0428 (7)
C7	0.05225 (19)	0.7561 (5)	−0.05762 (16)	0.0457 (7)
H7	0.025	0.8765	−0.1008	0.055*
C8	−0.02107 (19)	0.5923 (5)	−0.03256 (16)	0.0429 (7)
C9	−0.13335 (19)	0.6016 (5)	−0.06961 (16)	0.0446 (7)
H9	−0.1606	0.722	−0.1128	0.054*
C10	0.1906 (2)	1.0987 (5)	−0.12112 (17)	0.0501 (7)
H10A	0.1395	1.2188	−0.1063	0.06*
H10B	0.1497	0.9937	−0.1683	0.06*
C11	0.2731 (2)	1.2644 (6)	−0.14795 (19)	0.0597 (8)
H11A	0.322	1.1486	−0.1658	0.09*
H11B	0.314	1.3712	−0.1021	0.09*
H11C	0.236	1.3789	−0.193	0.09*
C12	0.36829 (19)	0.3617 (5)	0.15477 (17)	0.0470 (7)
H12	0.3269	0.1943	0.1437	0.056*
C13	0.4870 (2)	0.2951 (6)	0.16758 (19)	0.0586 (8)
H13A	0.5306	0.452	0.1855	0.088*
H13B	0.4974	0.2324	0.1163	0.088*
H13C	0.5088	0.1583	0.2091	0.088*
C14	0.3535 (2)	0.4794 (6)	0.23422 (18)	0.0586 (8)
H14A	0.2772	0.509	0.2276	0.088*
H14B	0.392	0.6462	0.246	0.088*
H14C	0.3819	0.3576	0.2794	0.088*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0426 (14)	0.0452 (14)	0.0469 (16)	−0.0039 (11)	0.0144 (11)	−0.0033 (11)
C2	0.0424 (14)	0.0539 (15)	0.0479 (16)	−0.0092 (12)	0.0153 (12)	−0.0026 (12)
C3	0.0405 (14)	0.0496 (15)	0.0564 (18)	−0.0035 (11)	0.0120 (12)	−0.0034 (12)
C4	0.0399 (13)	0.0459 (14)	0.0436 (15)	−0.0020 (11)	0.0099 (11)	−0.0050 (11)
C5	0.0383 (13)	0.0444 (14)	0.0422 (15)	−0.0013 (10)	0.0108 (10)	−0.0027 (11)
C6	0.0423 (14)	0.0432 (14)	0.0435 (16)	−0.0015 (10)	0.0134 (11)	−0.0016 (11)
C7	0.0408 (14)	0.0498 (15)	0.0461 (16)	0.0001 (11)	0.0117 (11)	0.0043 (11)
C8	0.0389 (14)	0.0438 (14)	0.0465 (16)	−0.0009 (10)	0.0129 (11)	−0.0001 (10)
C9	0.0398 (13)	0.0459 (14)	0.0454 (16)	0.0013 (11)	0.0074 (11)	0.0048 (11)
C10	0.0486 (16)	0.0493 (15)	0.0515 (18)	−0.0053 (11)	0.0125 (13)	0.0029 (12)
C11	0.0577 (18)	0.0622 (18)	0.061 (2)	−0.0058 (14)	0.0193 (15)	0.0121 (14)
C12	0.0398 (14)	0.0497 (15)	0.0491 (17)	−0.0002 (11)	0.0087 (11)	0.0013 (12)
C13	0.0436 (16)	0.0650 (18)	0.063 (2)	0.0063 (13)	0.0088 (13)	0.0059 (14)
C14	0.0576 (18)	0.0711 (19)	0.0466 (17)	0.0016 (14)	0.0140 (13)	0.0007 (14)

Geometric parameters (Å, º)

C1—C2	1.359 (3)	C9—H9	0.94
C1—C6	1.451 (3)	C10—C11	1.522 (3)
C1—C10	1.507 (4)	C10—H10A	0.98
C2—C3	1.422 (4)	C10—H10B	0.98
C2—H2	0.94	C11—H11A	0.97
C3—C4	1.362 (3)	C11—H11B	0.97
C3—H3	0.94	C11—H11C	0.97
C4—C5	1.448 (3)	C12—C13	1.522 (3)
C4—C12	1.516 (3)	C12—C14	1.534 (4)
C5—C9^i	1.394 (3)	C12—H12	0.99
C5—C6	1.448 (3)	C13—H13A	0.97
C6—C7	1.385 (3)	C13—H13B	0.97
C7—C8	1.411 (3)	C13—H13C	0.97
C7—H7	0.94	C14—H14A	0.97
C8—C9	1.406 (3)	C14—H14B	0.97
C8—C8^i	1.430 (5)	C14—H14C	0.97
C9—C5^i	1.394 (3)
C2—C1—C6	117.7 (2)	C11—C10—H10A	108.3
C2—C1—C10	122.9 (2)	C1—C10—H10B	108.3
C6—C1—C10	119.4 (2)	C11—C10—H10B	108.3
C1—C2—C3	122.2 (2)	H10A—C10—H10B	107.4
C1—C2—H2	118.9	C10—C11—H11A	109.5
C3—C2—H2	118.9	C10—C11—H11B	109.5
C4—C3—C2	123.0 (2)	H11A—C11—H11B	109.5
C4—C3—H3	118.5	C10—C11—H11C	109.5
C2—C3—H3	118.5	H11A—C11—H11C	109.5
C3—C4—C5	117.4 (2)	H11B—C11—H11C	109.5
C3—C4—C12	121.7 (2)	C4—C12—C13	114.0 (2)
C5—C4—C12	120.9 (2)	C4—C12—C14	110.1 (2)
C9^i—C5—C6	118.2 (2)	C13—C12—C14	109.4 (2)
C9^i—C5—C4	122.0 (2)	C4—C12—H12	107.7
C6—C5—C4	119.8 (2)	C13—C12—H12	107.7
C7—C6—C5	119.2 (2)	C14—C12—H12	107.7
C7—C6—C1	120.9 (2)	C12—C13—H13A	109.5
C5—C6—C1	119.8 (2)	C12—C13—H13B	109.5
C6—C7—C8	122.6 (2)	H13A—C13—H13B	109.5
C6—C7—H7	118.7	C12—C13—H13C	109.5
C8—C7—H7	118.7	H13A—C13—H13C	109.5
C9—C8—C7	122.6 (2)	H13B—C13—H13C	109.5
C9—C8—C8^i	119.0 (3)	C12—C14—H14A	109.5
C7—C8—C8^i	118.4 (3)	C12—C14—H14B	109.5
C5^i—C9—C8	122.7 (2)	H14A—C14—H14B	109.5
C5^i—C9—H9	118.7	C12—C14—H14C	109.5
C8—C9—H9	118.7	H14A—C14—H14C	109.5
C1—C10—C11	115.9 (2)	H14B—C14—H14C	109.5
C1—C10—H10A	108.3
C6—C1—C2—C3	1.5 (4)	C2—C1—C6—C5	−1.4 (4)
C10—C1—C2—C3	−177.3 (2)	C10—C1—C6—C5	177.4 (2)
C1—C2—C3—C4	−1.5 (4)	C5—C6—C7—C8	0.4 (4)
C2—C3—C4—C5	1.3 (4)	C1—C6—C7—C8	178.6 (2)
C2—C3—C4—C12	−177.3 (2)	C6—C7—C8—C9	−179.9 (2)
C3—C4—C5—C9^i	178.6 (2)	C6—C7—C8—C8^i	−0.6 (5)
C12—C4—C5—C9^i	−2.7 (4)	C7—C8—C9—C5^i	179.9 (2)
C3—C4—C5—C6	−1.2 (4)	C8^i—C8—C9—C5^i	0.7 (5)
C12—C4—C5—C6	177.4 (2)	C2—C1—C10—C11	−0.4 (4)
C9^i—C5—C6—C7	−0.4 (4)	C6—C1—C10—C11	−179.2 (2)
C4—C5—C6—C7	179.5 (2)	C3—C4—C12—C13	−22.5 (4)
C9^i—C5—C6—C1	−178.6 (2)	C5—C4—C12—C13	158.9 (2)
C4—C5—C6—C1	1.3 (4)	C3—C4—C12—C14	100.9 (3)
C2—C1—C6—C7	−179.6 (2)	C5—C4—C12—C14	−77.7 (3)
C10—C1—C6—C7	−0.7 (4)

Symmetry code: (i) −x, −y+1, −z.