1,5-Bis(piperidin-1-yl)-9,10-anthraquin­one

Niedziałkowski, P.; Wnuk, E.; Wcisło, A.; Trzybiński, D.

doi:10.1107/S1600536812050313

organic compounds

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ISSN: 2056-9890

Volume 69| Part 1| January 2013| Page o110

https://doi.org/10.1107/S1600536812050313

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1,5-Bis(piperidin-1-yl)-9,10-anthraquinone

Paweł Niedziałkowski,^a Elżbieta Wnuk,^a Anna Wcisło ^a and Damian Trzybiński ^a ^*

^aFaculty of Chemistry, University of Gdańsk, J. Sobieskiego 18, 80-952 Gdańsk, Poland
^*Correspondence e-mail: trzybinski@chem.univ.gda.pl

(Received 5 December 2012; accepted 10 December 2012; online 19 December 2012)

In the centrosymmetric title compound, C₂₄H₂₆N₂O₂, the piperidine ring adopts a chair conformation and is inclined at a dihedral angle of 37.5 (1)°to the anthracene ring system. In the crystal, adjacent molecules are linked through C—H⋯π and π–π [centroid–centroid distances = 3.806 (1) Å] interactions, forming a layer parallel to the bc plane.

Related literature

For general background to quinone compounds, see: Alves et al. (2004 ); El-Najjar et al. (2011 ); Czupryniak et al. (2012 ); Krohn (2008 ); Wannalerse et al. (2008 ). For related structures, see: Niedziałkowski et al. (2010 , 2011 ); Wnuk et al. (2012 ); Yatsenko et al. (2000 ).

Experimental

Crystal data

C₂₄H₂₆N₂O₂
M_r = 374.47
Monoclinic, P 2₁ /c
a = 10.9115 (4) Å
b = 7.0127 (2) Å
c = 12.5984 (5) Å
β = 97.819 (4)°
V = 955.05 (6) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 295 K
0.45 × 0.22 × 0.05 mm

Data collection

Oxford Diffraction Gemini R Ultra Ruby CCD diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008 $[Oxford Diffraction. (2008). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ) T_min = 0.909, T_max = 1.000
12625 measured reflections
1699 independent reflections
1274 reflections with I > 2σ(I)
R_int = 0.042

Refinement

R[F² > 2σ(F²)] = 0.041
wR(F²) = 0.102
S = 1.04
1699 reflections
127 parameters
H-atom parameters constrained
Δρ_max = 0.13 e Å⁻³
Δρ_min = −0.14 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg2 is the centroid of the C1–C6 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯Cg2ⁱ	0.93	2.98	3.850 (2)	156
Symmetry code: (i) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 $[Oxford Diffraction. (2008). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ); cell refinement: CrysAlis RED (Oxford Diffraction, 2008 $[Oxford Diffraction. (2008). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012 ); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536812050313/xu5662sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812050313/xu5662Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S1600536812050313/xu5662Isup3.cml

checkCIF report

Comment top

Quinone and quinone-derived compounds are widely distributed in the environment. They occur in many plants as physiologically active substances participating in photosynthetic electron transport processes (El-Najjar et al., 2011). Anthraquinones, both natural and synthetic, are coloring compounds with many applications in industry, mainly as pigments, food colorants and textile dyes. Some of the anthraquinone derivatives have been used for medical purposes as anticancer drugs and antitumor or antiviral agents (Alves et al., 2004; Krohn, 2008). Finally, derivatives belonging to this group of compounds are applied in molecular and supramolecular chemistry as optical and electrochemical sensors (Czupryniak et al., 2012; Wannalerse et al., 2008). This wide variety of practical applications make anthraquinone derivatives an important object of research and natural target in organic synthesis.

The crystal structures of some 9,10-anthraquinone derivatives were described in our previous papers (Niedziałkowski et al., 2010; Niedziałkowski et al., 2011; Wnuk et al., 2012). The purpose of this work is to report the crystal structure of 1,5-di(piperidin-1-yl)-9,10-anthraquinone.

The title compound has only half of molecule in the asymmetric part of the unit cell (Fig. 1). In the crystal structure, each half of molecule is arranged around an inversion centre located in the middle of the quinone ring. In the molecule of the title compound, likewise in other 9,10-anthraquinone derivatives (Niedziałkowski et al., 2010; Niedziałkowski et al., 2011; Wnuk et al., 2012, Yatsenko et al., 2000), deviation of planarity of the anthraquinone skeleton is observed. In case of the title compound, such distortion is found to be 0.0834 (3) Å. The piperidine rings adopt a chair conformation, with ring-puckering parameters Q = 0.5680 (18) Å, Θ = 178.23 (18)° and φ = 207 (6)°. The mean planes of piperidine and anthracene ring systems are inclined at a dihedral angle of 37.5 (1)°. The neighboring anthracene moieties are parallel or inclined at an angle of 63.3 (1)° in the crystal lattice. In the crystal, the adjacent molecules are linked by C—H···π (Table 2, Fig. 2) and π–π [centroid-centroid distances = 3.806 (1) Å] (Table 3, Fig. 2) interactions, forming a layer parallel to the bc plane.

Related literature top

For general background to quinone compounds, see: Alves et al. (2004); El-Najjar et al. (2011); Czupryniak et al. (2012); Krohn (2008); Wannalerse et al. (2008). For related structures, see: Niedziałkowski et al. (2010, 2011); Wnuk et al. (2012); Yatsenko et al. (2000).

Experimental top

To a solution of 1 g 1,5-bis(tosyloxy)-9,10-anthraquinone (1.823 mmol) in 50 ml of toluene 0.392 g of piperidine was added (4.775 mmol). The mixture was heated to 80°C. After 24 h the reaction mixture was cooled to room temperature. The resulting mixture was filtered and the solvent was removed under reduced pressure. The residue was dissolved in dichloromethane (200 ml) and washed with water (3 x 200 ml). The organic layer was dried over anhydrous MgSO₄ and concentrated under reduced pressure to obtain a red solid residue. This solid was purified by flash column chromatography (SiO₂, eluent: dichloromethane) to afford the 0.657 g (yield: 96%) of the title compound. Dark-red crystals suitable for X-ray investigations were grown from dichloromethane/methanol solution (1:1, v/v) (m.p. 207–208°C).

Spectral data:

¹H NMR (CDCl₃, 400MHz): δ (ppm): 1.628–1.686 (p, 2H, –N–CH₂–CH₂–CH₂–CH₂–CH₂–, J₁=5.6 Hz, J₁=6.0 Hz, J₂=5.8 Hz, J₂=6 Hz, J₃=11.8 Hz); 1.809–1.866 (p, 4H, –N–CH₂–CH₂–CH₂–CH₂–CH₂–, J₁=5.2 Hz, J₁=5.6 Hz, J₁=6.0 Hz, J₂=5.4 Hz, J₂=5.6 Hz, J₂=5.8 Hz, J₃=11.1 Hz); 3.137 3.164 (p, 4H, –N–CH₂–CH₂–CH₂–CH₂–CH₂–, J₁=5.2 Hz, J₁=5.6 Hz, J₂=5.4 Hz); 7.258–7.280 (d, 2H, H-2 Ar, H-4 Ar, J₁=8.8 Hz); 7.528–7.568 (t, 2H, H-3 Ar, H-7 Ar, J₁=J₂=8,0 Hz); 7.807–7.826 (d, 2H, H-6 Ar, H-8 Ar, Hz, J₁=7.6 Hz);

IR (KBr): 3434, 2940, 2855, 2813, 1648, 1582, 1423, 1381, 1226, 895, 710 (cm^–1);

MALDI-TOF MS: m/z 376.3 [M+H]⁺ (MW = 374.20).

Structure description top

For general background to quinone compounds, see: Alves et al. (2004); El-Najjar et al. (2011); Czupryniak et al. (2012); Krohn (2008); Wannalerse et al. (2008). For related structures, see: Niedziałkowski et al. (2010, 2011); Wnuk et al. (2012); Yatsenko et al. (2000).

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell refinement: CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The asymmetric part of the unit cell of the title compound, showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 25% probability level, and H atoms are shown as small spheres of arbitrary radius. Cg2 is the centroid of the C1–C6 ring.
	Fig. 2. The arrangement of the molecules in the crystal structure. The C—H···π and π–π interactions are represented by dotted lines. H atoms not involved in interactions have been omitted. [Symmetry codes: (i) –x, y – 1/2, –z + 1/2; (ii) –x, –y, –z + 1.]

1,5-Bis(piperidin-1-yl)-9,10-anthraquinone top

Crystal data top

C₂₄H₂₆N₂O₂	F(000) = 400
M_r = 374.47	D_x = 1.302 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5096 reflections
a = 10.9115 (4) Å	θ = 3.3–29.2°
b = 7.0127 (2) Å	µ = 0.08 mm⁻¹
c = 12.5984 (5) Å	T = 295 K
β = 97.819 (4)°	Plate, dark-red
V = 955.05 (6) Å³	0.45 × 0.22 × 0.05 mm
Z = 2

Data collection top

Oxford Diffraction Gemini R Ultra Ruby CCD diffractometer	1699 independent reflections
Radiation source: Enhanced (Mo) X-ray Source	1274 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.042
Detector resolution: 10.4002 pixels mm^-1	θ_max = 25.1°, θ_min = 3.3°
ω scans	h = −13→13
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008)	k = −8→8
T_min = 0.909, T_max = 1.000	l = −15→15
12625 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.102	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0491P)² + 0.0697P] where P = (F_o² + 2F_c²)/3
1699 reflections	(Δ/σ)_max < 0.001
127 parameters	Δρ_max = 0.13 e Å⁻³
0 restraints	Δρ_min = −0.14 e Å⁻³

Crystal data top

C₂₄H₂₆N₂O₂	V = 955.05 (6) Å³
M_r = 374.47	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 10.9115 (4) Å	µ = 0.08 mm⁻¹
b = 7.0127 (2) Å	T = 295 K
c = 12.5984 (5) Å	0.45 × 0.22 × 0.05 mm
β = 97.819 (4)°

Data collection top

Oxford Diffraction Gemini R Ultra Ruby CCD diffractometer	1699 independent reflections
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008)	1274 reflections with I > 2σ(I)
T_min = 0.909, T_max = 1.000	R_int = 0.042
12625 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.041	0 restraints
wR(F²) = 0.102	H-atom parameters constrained
S = 1.04	Δρ_max = 0.13 e Å⁻³
1699 reflections	Δρ_min = −0.14 e Å⁻³
127 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.09986 (14)	0.19940 (19)	0.37606 (11)	0.0393 (4)
C2	0.01598 (16)	0.0605 (2)	0.33222 (14)	0.0513 (4)
H2	0.0428	−0.0338	0.2889	0.062*
C3	−0.10447 (16)	0.0595 (2)	0.35124 (15)	0.0559 (5)
H3	−0.1586	−0.0320	0.3184	0.067*
C4	−0.14652 (15)	0.1917 (2)	0.41814 (13)	0.0472 (4)
H4	−0.2273	0.1852	0.4338	0.057*
C5	−0.06790 (13)	0.33481 (18)	0.46218 (12)	0.0383 (4)
C6	0.05433 (13)	0.34603 (18)	0.43854 (11)	0.0368 (4)
C7	0.12218 (14)	0.5249 (2)	0.46817 (13)	0.0430 (4)
O8	0.21900 (12)	0.56569 (16)	0.43513 (12)	0.0720 (4)
N9	0.22226 (11)	0.19390 (17)	0.35623 (10)	0.0436 (3)
C10	0.32009 (14)	0.1930 (2)	0.44808 (12)	0.0499 (4)
H10A	0.3308	0.0645	0.4763	0.060*
H10B	0.2961	0.2742	0.5041	0.060*
C11	0.44077 (15)	0.2628 (3)	0.41651 (14)	0.0588 (5)
H11A	0.5047	0.2570	0.4780	0.071*
H11B	0.4320	0.3946	0.3934	0.071*
C12	0.47827 (16)	0.1425 (3)	0.32700 (15)	0.0609 (5)
H12A	0.4974	0.0141	0.3527	0.073*
H12B	0.5518	0.1958	0.3030	0.073*
C13	0.37392 (16)	0.1369 (3)	0.23460 (14)	0.0578 (5)
H13A	0.3628	0.2630	0.2032	0.069*
H13B	0.3958	0.0507	0.1800	0.069*
C14	0.25403 (16)	0.0721 (2)	0.27005 (14)	0.0537 (5)
H14A	0.1884	0.0772	0.2099	0.064*
H14B	0.2621	−0.0588	0.2948	0.064*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0474 (9)	0.0385 (8)	0.0304 (8)	−0.0024 (6)	−0.0002 (7)	0.0035 (6)
C2	0.0595 (11)	0.0423 (9)	0.0505 (11)	−0.0062 (8)	0.0019 (9)	−0.0084 (7)
C3	0.0566 (11)	0.0439 (9)	0.0651 (12)	−0.0167 (8)	0.0002 (9)	−0.0133 (8)
C4	0.0447 (9)	0.0413 (8)	0.0546 (10)	−0.0110 (7)	0.0028 (8)	−0.0001 (7)
C5	0.0438 (9)	0.0341 (7)	0.0354 (8)	−0.0056 (6)	−0.0009 (7)	0.0058 (6)
C6	0.0425 (9)	0.0349 (7)	0.0313 (8)	−0.0050 (6)	−0.0012 (7)	0.0029 (6)
C7	0.0424 (9)	0.0419 (8)	0.0444 (10)	−0.0089 (7)	0.0049 (8)	0.0008 (7)
O8	0.0637 (8)	0.0614 (8)	0.0985 (11)	−0.0251 (6)	0.0386 (8)	−0.0237 (7)
N9	0.0458 (8)	0.0498 (7)	0.0340 (7)	0.0008 (6)	0.0010 (6)	−0.0046 (6)
C10	0.0501 (10)	0.0603 (10)	0.0375 (10)	−0.0003 (7)	−0.0009 (8)	0.0037 (8)
C11	0.0489 (11)	0.0720 (11)	0.0539 (11)	−0.0041 (8)	0.0018 (9)	0.0006 (9)
C12	0.0520 (11)	0.0673 (11)	0.0640 (13)	0.0094 (8)	0.0101 (9)	0.0045 (9)
C13	0.0668 (12)	0.0613 (10)	0.0478 (11)	0.0120 (9)	0.0162 (9)	−0.0037 (9)
C14	0.0614 (11)	0.0528 (9)	0.0457 (11)	0.0040 (8)	0.0032 (9)	−0.0116 (8)

Geometric parameters (Å, º) top

C1—N9	1.3923 (19)	N9—C10	1.4637 (19)
C1—C2	1.398 (2)	C10—C11	1.508 (2)
C1—C6	1.425 (2)	C10—H10A	0.9700
C2—C3	1.368 (2)	C10—H10B	0.9700
C2—H2	0.9300	C11—C12	1.509 (2)
C3—C4	1.373 (2)	C11—H11A	0.9700
C3—H3	0.9300	C11—H11B	0.9700
C4—C5	1.386 (2)	C12—C13	1.514 (2)
C4—H4	0.9300	C12—H12A	0.9700
C5—C6	1.4078 (19)	C12—H12B	0.9700
C5—C7ⁱ	1.493 (2)	C13—C14	1.509 (2)
C6—C7	1.479 (2)	C13—H13A	0.9700
C7—O8	1.2209 (18)	C13—H13B	0.9700
C7—C5ⁱ	1.493 (2)	C14—H14A	0.9700
N9—C14	1.4595 (19)	C14—H14B	0.9700

N9—C1—C2	120.15 (13)	N9—C10—H10B	109.4
N9—C1—C6	122.30 (13)	C11—C10—H10B	109.4
C2—C1—C6	117.53 (14)	H10A—C10—H10B	108.0
C3—C2—C1	121.86 (15)	C10—C11—C12	110.53 (15)
C3—C2—H2	119.1	C10—C11—H11A	109.5
C1—C2—H2	119.1	C12—C11—H11A	109.5
C2—C3—C4	120.87 (14)	C10—C11—H11B	109.5
C2—C3—H3	119.6	C12—C11—H11B	109.5
C4—C3—H3	119.6	H11A—C11—H11B	108.1
C3—C4—C5	119.62 (15)	C11—C12—C13	109.70 (14)
C3—C4—H4	120.2	C11—C12—H12A	109.7
C5—C4—H4	120.2	C13—C12—H12A	109.7
C4—C5—C6	120.55 (14)	C11—C12—H12B	109.7
C4—C5—C7ⁱ	116.03 (14)	C13—C12—H12B	109.7
C6—C5—C7ⁱ	123.40 (12)	H12A—C12—H12B	108.2
C5—C6—C1	119.22 (12)	C14—C13—C12	111.83 (15)
C5—C6—C7	116.76 (13)	C14—C13—H13A	109.3
C1—C6—C7	123.47 (13)	C12—C13—H13A	109.3
O8—C7—C6	122.64 (14)	C14—C13—H13B	109.3
O8—C7—C5ⁱ	118.49 (13)	C12—C13—H13B	109.3
C6—C7—C5ⁱ	118.83 (13)	H13A—C13—H13B	107.9
C1—N9—C14	118.71 (12)	N9—C14—C13	110.33 (13)
C1—N9—C10	118.19 (12)	N9—C14—H14A	109.6
C14—N9—C10	111.35 (12)	C13—C14—H14A	109.6
N9—C10—C11	111.04 (13)	N9—C14—H14B	109.6
N9—C10—H10A	109.4	C13—C14—H14B	109.6
C11—C10—H10A	109.4	H14A—C14—H14B	108.1

N9—C1—C2—C3	178.97 (15)	C1—C6—C7—O8	5.0 (2)
C6—C1—C2—C3	−2.4 (2)	C5—C6—C7—C5ⁱ	11.1 (2)
C1—C2—C3—C4	−2.6 (3)	C1—C6—C7—C5ⁱ	−177.48 (13)
C2—C3—C4—C5	3.7 (3)	C2—C1—N9—C14	14.6 (2)
C3—C4—C5—C6	0.2 (2)	C6—C1—N9—C14	−163.92 (13)
C3—C4—C5—C7ⁱ	178.57 (15)	C2—C1—N9—C10	−125.26 (15)
C4—C5—C6—C1	−5.3 (2)	C6—C1—N9—C10	56.21 (18)
C7ⁱ—C5—C6—C1	176.55 (13)	C1—N9—C10—C11	−157.87 (14)
C4—C5—C6—C7	166.56 (14)	C14—N9—C10—C11	59.50 (17)
C7ⁱ—C5—C6—C7	−11.6 (2)	N9—C10—C11—C12	−57.34 (18)
N9—C1—C6—C5	−175.20 (13)	C10—C11—C12—C13	54.17 (19)
C2—C1—C6—C5	6.2 (2)	C11—C12—C13—C14	−54.10 (19)
N9—C1—C6—C7	13.6 (2)	C1—N9—C14—C13	159.33 (13)
C2—C1—C6—C7	−164.99 (14)	C10—N9—C14—C13	−58.25 (17)
C5—C6—C7—O8	−166.46 (16)	C12—C13—C14—N9	56.03 (18)

Symmetry code: (i) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

Cg2 is the centroid of the C1–C6 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···Cg2ⁱⁱ	0.93	2.98	3.850 (2)	156

Symmetry code: (ii) −x, y−1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	C₂₄H₂₆N₂O₂
M_r	374.47
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	295
a, b, c (Å)	10.9115 (4), 7.0127 (2), 12.5984 (5)
β (°)	97.819 (4)
V (Å³)	955.05 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.45 × 0.22 × 0.05

Data collection
Diffractometer	Oxford Diffraction Gemini R Ultra Ruby CCD
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2008)
T_min, T_max	0.909, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	12625, 1699, 1274
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.597

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.041, 0.102, 1.04
No. of reflections	1699
No. of parameters	127
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.13, −0.14

Computer programs: CrysAlis CCD (Oxford Diffraction, 2008), CrysAlis RED (Oxford Diffraction, 2008), SHELXS97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 2012), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg2 is the centroid of the C1–C6 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···Cg2ⁱ	0.93	2.98	3.850 (2)	156

Symmetry code: (i) −x, y−1/2, −z+1/2.

The π–π interaction geometry (Å,°). top

I	J	CgI···CgJ	Dihedral angle	CgI_Perp	CgJ_Perp	CgI_Offset	CgJ_Offset
2	2ⁱⁱ	3.806 (1)	0	3.702 (1)	3.702 (1)	0.884 (1)	0.884 (1)

Symmetry code: (ii) –x, –y, –z + 1.

Notes: Cg2 is the centroid of the C1–C6 ring. CgI···CgJ is the distance between ring centroids. The dihedral angle is that between the planes of the rings I and J. CgI_Perp is the perpendicular distance of CgI from ring J. CgJ_Perp is the perpendicular distance of CgJ from ring I. CgI_Offset is the distance between CgI and perpendicular projection of CgJ on ring I. CgJ_Offset is the distance between CgJ and perpendicular projection of CgI on ring J.

Acknowledgements

This study was financed by the State Funds for Scientific Research through National Center for Science grant No. N N204 122 640 and by the University of Gdańsk within the project supporting young scientists and PhD students (grant No. 538-8210-1029-12).

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