5,5-Bis(4-methoxy-phen-yl)-2,8-bis-[3-(trifluoro-meth-yl)phen-yl]-5H-cyclo-penta-[2,1-b:3,4-b']dipyridine.

The title compound, C(39)H(26)F(6)N(2)O(2), showed two melting transitions 477.4 and 506.5 K in a differential scanning calorimetry (DSC) study. The first of these can be attributed to a melting phase transition arising from the rotation of two trifluoro-methyl groups. In the crystal structure, both trifluoro-methyl groups are disordered over two sites with occupancy factors of 0.660 (17) and 0.340 (17) for the major and minor orientations, respectively. The introduction of trifluoro-methyl groups inhibits π-stacking between the diaza-fluorene (cyclo-penta-[2,1-b:3,4-b']dipyridine) units. Three short F⋯O contacts between 2.80 (3) and 2.95 (1) Å are observed in the crystal structure.

The title compound, C 39 H 26 F 6 N 2 O 2 , showed two melting transitions 477.4 and 506.5 K in a differential scanning calorimetry (DSC) study. The first of these can be attributed to a melting phase transition arising from the rotation of two trifluoromethyl groups. In the crystal structure, both trifluoromethyl groups are disordered over two sites with occupancy factors of 0.660 (17) and 0.340 (17) for the major and minor orientations, respectively. The introduction of trifluoromethyl groups inhibits -stacking between the diazafluorene (cyclopenta[2,1-b:3,4-b']dipyridine) units. Three short FÁ Á ÁO contacts between 2.80 (3) and 2.95 (1) Å are observed in the crystal structure.

Related literature
The synthesis and thermal properties of the title compound were reported by Ono et al. (2007). For related literature on molecular and crystal structures, including the 4,5-diazafluorene system, see: Ono & Saito (2008).

S2. Experimental
The title compound (I) was synthesized by the direct arylation reaction of mono-substituted compound (II), which was also prepared by the direct arylation of 5,5-bis(4-methoxyphenyl)-5H-cyclopenta[2,1-b:3,4-b′]dipyridine (III). The direct arylation of compound (II) was performed as follows: nBuLi in hexane (1.60 M, 3.3 ml, 5.2 mmol) was added dropwise to a solution of 3-bromobenzotrifluoride (0.66 ml, 4.8 mmol) in dry ether (20 ml) at 195 K under nitrogen. The solution was stirred at 195 K for 30 min and at 0 °C for 30 min. Compound (II) (1.52 g, 4.0 mmol) and dry toluene (30 ml) were added to the solution at 253 K. The reaction mixture was stirred at 253 K for 30 min and at room temperature overnight.
The mixture was poured into water and dichloromethane was added. The organic layer was separated and aqueous layer was extracted with dichloromethane (× 2). Manganese(IV) oxide (MnO 2 ) (10 g) was added to the combined organic solution and the mixture was stirred for 30 min. Further, anhydrous magnesium sulfate (MgSO 4 ) (10 g) was added and the mixture was stirred for 30 min. After filtration and condensation, the residue was chromatographed on silica gel (hexane/ethyl acetate = 3:1 v/v) to afford the title compound as a white solid (1.28 g, 39%). Colorless prisms of (I) suitable for X-ray analysis were grown from an acetonitrile solution.

S3. Refinement
Anomalous dispersion was negligible and Friedel pairs were merged before refinement. All the H atoms were placed in geometrically calculated positions, with C-H = 0.95 (phenyl) and 0.98 (methyl) Å, and refined using a riding model with U iso (H) = 1.2U eq (C) (phenyl) and 1.5U eq (C) (methyl).

Figure 1
The DSC profile of (I).  The molecular structure of (I), with 50% probability displacement elipsoids for non-H atoms and H atoms are shown as small spheres of arbitrary radius. The disordered fluorine atoms (F7-F12) of the two trifluoromethyl groups are omitted for clarity.  The packing diagram of (I).  Special details Experimental. IR (KBr, cm -1 ): 1607,1574,1510,1337,1298,1256,1175,1130,1073,1030,837,808 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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. The fluorine atoms of the two trifluoromethyl groups are disordered over two sites (F1-F6 and F7-F12) with occupancies of 0.66 (2) (3)