3,9′-Bi(9H-fluorene)

Jie Liu; Wentao Yu

doi:10.1107/S1600536812024841

. 2012 Jun 13;68(Pt 7):o2081. doi: 10.1107/S1600536812024841

3,9′-Bi(9H-fluorene)

Jie Liu ^a,^*, Wentao Yu ^a

PMCID: PMC3393897 PMID: 22798762

Abstract

The title compound [systematic name: 9-(9H-fluoren-3-yl)-9H-fluorene], C₂₆H₁₈, was obtained unintentionally as the product of the synthesis of a compound based on fluorene–thiophene units. The two fluorene rings are connected through C atoms in the 3- and 9′-positions, and the dihedral angle between the mean planes of the two fluorene units is 78.57 (6)°.

Related literature

For the crystal structures of related compounds, see: Dougherty et al. (1978 ▶); Sridevi et al. (2006 ▶). For the synthesis of the compound, see: Stille et al. (1993 ▶, 1998 ▶); Grasa & Nolan (2001 ▶). For the intermolecular C—H⋯π interactions, see: Tsuzuki et al. (2000 ▶); Nishio (2004 ▶). graphic file with name e-68-o2081-scheme1.jpg

Experimental

Crystal data

C₂₆H₁₈
M _r = 330.40
Orthorhombic,
a = 6.22600 (1) Å
b = 8.3968 (2) Å
c = 33.5357 (7) Å
V = 1753.20 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 293 K
0.45 × 0.22 × 0.16 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (APEX2; Bruker, 2005 ▶) T _min = 0.969, T _max = 0.989
15454 measured reflections
2352 independent reflections
2014 reflections with I > 2σ(I)
R _int = 0.032

Refinement

R[F ² > 2σ(F ²)] = 0.035
wR(F ²) = 0.091
S = 1.04
2352 reflections
235 parameters
H-atom parameters constrained
Δρ_max = 0.11 e Å⁻³
Δρ_min = −0.14 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: APEX2; data reduction: APEX2; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and Mercury (Macrae et al., 2006 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812024841/zj2080sup1.cif

e-68-o2081-sup1.cif^{(20.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812024841/zj2080Isup2.hkl

e-68-o2081-Isup2.hkl^{(113.2KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812024841/zj2080Isup3.mol

Supplementary material file. DOI: 10.1107/S1600536812024841/zj2080Isup4.cml

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

Acknowledgments

The authors gratefully acknowledge the National Natural Science Foundation of China (grant No. 51021062) and the 973 program of the People’s Republic of China (grant No. 2010CB630702).

supplementary crystallographic information

Comment

The molecule of the title complound (I) (Fig. 1) as the isomer of 9,9'-bi-9H-fluorene (9,9'-BF) is noncentrosymmetric, and the space group is P2₁2₁2₁. The two fluorene groups of the compound are like the letter 'T' in shape with a dihedral angle of 78.57 (6)°. Also, it is found that benzene rings of the fluorene units are not in the same plane, and the dihedral angles are 10.54 (6) and 5.84 (6)°, respectively. The crystal packing is stabilized by intermolecular C—-H···π interactions (Fig. 3).

Experimental

The title compound, 3,9'-BF, was obtained unintentionally as the product of an attempted synthesis of 2,5-bis(9H-fluoren-9-yl)thiophene through Still reaction method. n-Butyllithium (20 ml, 2.5 M in hexane, 50 mmol) was added dropwise at -78 °C into a consistently stirred mixture of thiophene (22 mmol, 1.8 ml) and dry THF (80 ml), and the mixture would be with further stirring for 2 h at room temperature under an atmosphere of dry argon. After cooling the reaction mixture to -78 °C tri-n-butyltin chloride (15 ml) was added drop-wise to the mixture system. Then, the mixture was stirred continuously over one night before being poured into saturated NH₄Cl water solution (100 ml). After extraction with diethyl ether, the organic layer was dried over anhydrous MgSO₄ and the yellow fluid bis[tri-n-butyltin] thiophene (TBSB) was obtained. Furthermore, DMF (10 ml) was added to the mixture of TBSB (2.5 mmol, 1.654 g), 9-bromo-fluorene (6.25 mmol, 1.53 g) and potassium fluoride (2.5 mmol, 0.145 g) with stirring about 15 min. Appropriate amount of tetrakis (triphenylphosphine) palladium (0) was added to the stirring system and refluxed at 100 °C for 16 h under an atmosphere of dry argon. After extraction with dichloromethane (30 ml), the mixture was purified by silica-gel column chromatography to give 3,9'-BF, 9,9'-BF and 2,5-bis(9H-fluoren-9-yl)thiophene. Finally, single crystals of 3,9'-BF were obtained by recrystallizing from dichloromethane.