9-Ethynyl-9H-carbazole

The title compound, C14H9N, is the second crystallographically characterized example of an ynamine with an H atom in the C-terminal position. There are two independent molecules (A and B) in the asymmetric unit. The structures of both molecules are essentially planar (r.m.s. deviation = 0.0312 and 0.0152 Å). The N—Csp bond lengths are 1.353 (4) and 1.350 (4) Å, and those of the acetylene bonds are 1.189 (4) and 1.190 (4) Å. The Csp—H bond lengths are 0.95 (5) and 0.97 (4) Å. These geometries are consistent with those of the previously reported ynamine characterized by crystallography. In the crystal, the molecules stack along the c axis, forming two kinds of columnar structures. The acetylene C atoms of molecule A have a short contact [3.341 (4) Å and 3.396 (4) Å] with an adjacent molecule A at the C—C bond of the fused part, which originates in π–π stacking interaction; no remarkable spatial contact is recognized within the stacking of molecule B.

The title compound, C 14 H 9 N, is the second crystallographically characterized example of an ynamine with an H atom in the Cterminal position. There are two independent molecules (A and B) in the asymmetric unit. The structures of both molecules are essentially planar (r.m.s. deviation = 0.0312 and 0.0152 Å ). The N-C sp bond lengths are 1.353 (4) and 1.350 (4) Å , and those of the acetylene bonds are 1.189 (4) and 1.190 (4) Å . The C sp -H bond lengths are 0.95 (5) and 0.97 (4) Å . These geometries are consistent with those of the previously reported ynamine characterized by crystallography. In the crystal, the molecules stack along the c axis, forming two kinds of columnar structures. The acetylene C atoms of molecule A have a short contact [3.341 (4) Å and 3.396 (4) Å ] with an adjacent molecule A at the C-C bond of the fused part, which originates instacking interaction; no remarkable spatial contact is recognized within the stacking of molecule B.
The molecules stack along the c axis, forming two kinds of columnar structures. The spatial contact between Molecules A is recognized within the columnar stack. The acetylenic carbons of C13 and C14 show the short contact with C7 i [Symmetry codes:(i) x, y, z -1.] and C12 i , where the distances of C13···C7 i and C14···C12 i are 3.341 (4) Å and 3.396 (4) Å, respectively, indicating π-π stacking interaction. While remarkable spatial contact is not recognized within the stacking of Molecule B.

Experimental
The title compound was prepared according to a published procedure (Cuniberti et al., 1996). The purification of the compound was performed by gel permeation chromatography (GPC). The single crystals with sufficient quality for X-ray analysis were obtained by concentration of an ethereal solution in a refrigerator.

Refinement
Friedel pairs were merged because the molecule itself was achiral and because there were not any anomalous scattering effects. The C-bound H atoms except two C sp -H atoms were placed at ideal positions and were refined as riding on their parent C atoms. U iso (H) values of the H atoms were set at 1.2U eq (parent atom). The C sp -bound H atoms were obtained from a difference Fourier map and were refined isotropically without any restrictions.

Figure 1
The asymmetric unit of the title compound with displacement ellipsoids drawn at the 50% probability level.

9-Ethynyl-9H-carbazole
Special details Refinement. Refinement was performed using all reflections except for 2 with very negative F 2 . The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).