Di-9-anthryl disulfide at 193 K

The title compound, C₂₈H₁₈S₂, crystallizes in the monoclinic space group P2₁/n and the structure shows pseudosymmetry close to the space group C2/c. At 193 K the compound has a long S-S bond of 2.1089 (12) Å and the S atom to anthracene bond distances are 1.776 (3) and 1.770 (2) Å. The C-S-S-C torsion angle is 76.06 (13)°.

S1. Comment

The crystal structure determination of 9-dianthryl disulfide, (I), is part of our investigation dealing with polyaromatic sulfides (Kansikas & Sipilä, 1997, 1999; Sipilä & Hase, 1997; Sipilä et al., 1999). A simple preparation method for (I) has been reported by Majumdar et al. (1986), who synthesized the product in 90% yield by refluxing anthrone, P₂S₅ and anhydrous pyridine for 5 h. The compound used in this X-ray analysis was obtained as a side product when testing preparation methods for 9-anthracenethiol. The orange-coloured blocks used for the structure determination were slowly recrystallized from absolute ethanol. The melting point (490 K) was measured in an open capillary tube with an electrothermal apparatus and is uncorrected. The melting points reported earlier vary from 477 K to 496 K (Friedländer & Simon, 1922; Majumdar et al., 1986).

When compared with other aromatic bis-compounds joined by the disulfide group, the S–S' distance of 2.1089 (12) Å found in (I) is relatively long. An even longer S–S bond of 2.113 (1) Å has been reported in an exceptional structure of the chloro[bis(2-pyrimidyl)disulfide]copper(I) complex, where the torsion angle C–S–S–C is 180° due to symmetry (Simmons et al., 1979). Some other long S–S bonds reported in the Cambridge Structural Database (CSD; Allen et al., 1991) are 2.073 Å in bis(1-methyluracil)-5,5'-disulfide (Shefter, 1970), 2.075 Å in bis[2-methyl-benzo(b)thien-3-yl]disulfide (Schaumann et al., 1979) and 2.080 Å in bis[2-(phenyl)thieno(3,2 − g) quinoxaline-3-yl]disulfide (Soricelli et al., 1991). The S atom distances of 1.776 (3) and 1.770 (2) Å to the aromatic C atom are comparable with those found in the literature (Simmons et al., 1979 and refs. therein).

The value of 76.06 (13)° for the C9–S–S'–C9' torsion angle is small compared with those in most disulfide groups joining aromatic rings listed in the CSD. The relatively small angle of 37.1 (1)° between the phenanthrene planes within one molecule causes stacking in the molecular packing, where the S–S' bonds connect the more or less parallel aromatic layers. The appearance is closely similar to the packing of bis[2-(phenyl)thieno(3,2 − g)quinoxaline-3-yl]disulfide, where, however, a C₂ axis through the S–S bond exists (Soricelli et al., 1991).

S2. Experimental

Compound (I) was a sideproduct in the preparation of anthracene-9-thiol using the method of Testaferri et al. (1983). Potassium propanethiolate was refluxed with 9-bromoanthracene for 2 h in dimethylformamide and the product was dealkylated with potassium t-butoxide by refluxing for several hours in a one-pot reaction. A nitrogen atmosphere was not used. The reaction mixture was poured into 1 M HCl and extracted with diethyl ether. The organic layer was washed with water, dried with sodium sulfate and evaporated. The residue was only partly soluble in dichloromethane–ligroin (1:3) used as a solvent in the flash chromatography of the crude product. The insoluble yellow powder was crystallized from ethanol to obtain 9-dianthryl disulfide (10% yield).

S3. Refinement

The reciprocal space exploring program XPREP (SHELXTL/PC; Sheldrick, 1990a) indicated the space group P2₁/n and the structure was readily solved. However, the appearance of the molecular packing suggested a closer inspection of the reciprocal lattice planes. Those hkl reflections with h + k = 2n + 1, corresponding to the forbidden reflections in the space group C2/c, were considerably weaker than the other reflections but were clearly visible. When the structure was solved in this space group, the asymmetric unit consisted of half of the molecule. The final R₁-value converged to 0.0792, several correlation matrix elements exceeded the value of 1/2, and isotropic displacement parameters of atoms C2, C3, C4, C6 and C7 showed disorder. For these reasons, the present solution was chosen. Both of these space groups have been reported for symmetric or pseudosymmetric disulfides, e.g. P2₁/c (Neidlein et al., 1990; Shefter, 1970) and C2/c (Acheson et al., 1980; Ricci & Bernal, 1969).

Computing details

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: WinGX (Farrugia, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990b); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Sheldrick, 1990a); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. View of (I) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.

Di-9-anthryl disulfide

Crystal data

C28H18S2	F(000) = 872
Mr = 418.54	Dx = 1.337 Mg m^−3
Monoclinic, P21/n	Cu Kα radiation, λ = 1.54180 Å
a = 8.8330 (18) Å	Cell parameters from 25 reflections
b = 16.833 (3) Å	θ = 4–10°
c = 14.335 (3) Å	µ = 2.40 mm^−1
β = 102.65 (3)°	T = 193 K
V = 2079.7 (7) Å^3	Block, orange
Z = 4	0.29 × 0.27 × 0.25 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.061
Radiation source: fine-focus sealed tube	θmax = 63.7°, θmin = 4.1°
Graphite monochromator	h = −10→9
ω/2θ scans	k = −19→0
3443 measured reflections	l = 0→16
3305 independent reflections	3 standard reflections every 200 reflections
2639 reflections with I > 2σ(I)	intensity decay: 1.1%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.055	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.156	H-atom parameters constrained
S = 1.03	Calculated w = 1/[σ^2(Fo^2) + (0.1047P)^2 + 1.0329P] where P = (Fo^2 + 2Fc^2)/3
3305 reflections	(Δ/σ)max = 0.005
271 parameters	Δρmax = 0.45 e Å^−3
0 restraints	Δρmin = −0.69 e Å^−3

Special details

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 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 > σ(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
S	0.12074 (7)	0.21656 (4)	0.79039 (4)	0.0255 (2)
S'	−0.11167 (7)	0.21376 (4)	0.71312 (4)	0.0242 (2)
C1	−0.0030 (3)	0.20217 (17)	0.97654 (19)	0.0294 (6)
H1B	−0.0048	0.1598	0.9325	0.035*
C1'	−0.2476 (3)	0.37626 (17)	0.7513 (2)	0.0322 (6)
H1'A	−0.2361	0.3331	0.7950	0.039*
C2	−0.0608 (3)	0.19021 (19)	1.0571 (2)	0.0356 (7)
H2A	−0.1045	0.1402	1.0673	0.043*
C2'	−0.3172 (4)	0.44357 (18)	0.7719 (2)	0.0430 (8)
H2'A	−0.3524	0.4470	0.8298	0.052*
C3	−0.0557 (3)	0.2512 (2)	1.12457 (19)	0.0375 (7)
H3A	−0.0950	0.2421	1.1802	0.045*
C3'	−0.3382 (4)	0.50876 (19)	0.7086 (3)	0.0545 (9)
H3'A	−0.3903	0.5551	0.7227	0.065*
C4	0.0047 (3)	0.32269 (19)	1.11068 (19)	0.0372 (7)
H4A	0.0078	0.3633	1.1571	0.045*
C4'	−0.2832 (4)	0.50474 (18)	0.6269 (3)	0.0495 (9)
H4'A	−0.2949	0.5494	0.5854	0.059*
C4a	0.0647 (3)	0.33873 (17)	1.02663 (18)	0.0282 (6)
C4a'	−0.2085 (3)	0.43510 (16)	0.6024 (2)	0.0327 (6)
C5	0.2418 (4)	0.50554 (19)	0.9131 (2)	0.0479 (8)
H5A	0.2495	0.5453	0.9610	0.057*
C5'	−0.0154 (3)	0.3605 (2)	0.40949 (19)	0.0390 (7)
H5'A	−0.0239	0.4058	0.3692	0.047*
C6	0.2888 (4)	0.5222 (2)	0.8307 (3)	0.0527 (9)
H6A	0.3299	0.5730	0.8216	0.063*
C6'	0.0558 (4)	0.2937 (2)	0.3864 (2)	0.0449 (9)
H6'A	0.0983	0.2931	0.3310	0.054*
C7	0.2763 (4)	0.4639 (2)	0.7596 (2)	0.0449 (8)
H7B	0.3061	0.4765	0.7016	0.054*
C7'	0.0664 (4)	0.2262 (2)	0.4441 (2)	0.0414 (8)
H7'A	0.1155	0.1800	0.4269	0.050*
C8	0.2226 (3)	0.38992 (18)	0.7717 (2)	0.0326 (7)
H8A	0.2174	0.3515	0.7226	0.039*
C8'	0.0071 (3)	0.22521 (17)	0.52546 (19)	0.0313 (6)
H8'A	0.0138	0.1781	0.5627	0.038*
C8a	0.1732 (3)	0.36869 (15)	0.85780 (18)	0.0260 (6)
C8a'	−0.0642 (3)	0.29458 (16)	0.55398 (18)	0.0251 (6)
C9	0.1176 (3)	0.29335 (15)	0.87491 (17)	0.0226 (6)
C9'	−0.1232 (3)	0.29842 (15)	0.63869 (17)	0.0223 (6)
C9a	0.0592 (3)	0.27687 (15)	0.95834 (17)	0.0246 (6)
C9a'	−0.1905 (3)	0.36803 (15)	0.66540 (18)	0.0248 (6)
C10	0.1261 (4)	0.41235 (17)	1.01151 (19)	0.0354 (7)
H10B	0.1312	0.4526	1.0585	0.042*
C10'	−0.1503 (3)	0.43059 (18)	0.5188 (2)	0.0372 (7)
H10A	−0.1610	0.4754	0.4776	0.045*
C10a	0.1811 (3)	0.42893 (17)	0.92848 (19)	0.0319 (6)
C10a'	−0.0781 (3)	0.36310 (17)	0.49451 (18)	0.0301 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S	0.0330 (4)	0.0297 (4)	0.0149 (4)	0.0071 (3)	0.0074 (3)	−0.0009 (2)
S'	0.0343 (4)	0.0246 (4)	0.0141 (4)	−0.0025 (2)	0.0063 (3)	0.0021 (2)
C1	0.0342 (15)	0.0349 (15)	0.0191 (13)	−0.0021 (12)	0.0057 (11)	0.0008 (11)
C1'	0.0386 (15)	0.0350 (15)	0.0250 (14)	−0.0004 (12)	0.0112 (12)	−0.0026 (12)
C2	0.0375 (16)	0.0478 (17)	0.0215 (14)	−0.0086 (13)	0.0064 (12)	0.0075 (13)
C2'	0.0481 (18)	0.0421 (17)	0.0440 (18)	0.0004 (15)	0.0212 (15)	−0.0132 (14)
C3	0.0385 (16)	0.060 (2)	0.0174 (13)	−0.0010 (14)	0.0127 (12)	0.0060 (13)
C3'	0.064 (2)	0.0321 (17)	0.077 (3)	0.0065 (16)	0.037 (2)	−0.0055 (17)
C4	0.0453 (18)	0.0525 (19)	0.0164 (14)	0.0026 (14)	0.0125 (12)	−0.0050 (13)
C4'	0.054 (2)	0.0303 (16)	0.071 (2)	0.0065 (14)	0.0274 (18)	0.0117 (16)
C4a	0.0318 (14)	0.0391 (15)	0.0140 (12)	0.0022 (12)	0.0055 (10)	−0.0007 (11)
C4a'	0.0331 (15)	0.0285 (14)	0.0375 (16)	−0.0027 (12)	0.0101 (12)	0.0049 (12)
C5	0.067 (2)	0.0340 (17)	0.0429 (18)	−0.0125 (15)	0.0122 (16)	−0.0033 (14)
C5'	0.0370 (16)	0.063 (2)	0.0178 (13)	−0.0056 (15)	0.0088 (12)	0.0129 (14)
C6	0.064 (2)	0.0410 (18)	0.055 (2)	−0.0152 (17)	0.0177 (17)	0.0087 (17)
C6'	0.0400 (18)	0.083 (3)	0.0147 (14)	−0.0065 (17)	0.0118 (13)	−0.0013 (15)
C7	0.0468 (19)	0.053 (2)	0.0385 (17)	−0.0057 (15)	0.0172 (14)	0.0102 (15)
C7'	0.0458 (18)	0.060 (2)	0.0215 (15)	−0.0003 (15)	0.0134 (13)	−0.0120 (14)
C8	0.0349 (15)	0.0401 (16)	0.0255 (14)	0.0005 (12)	0.0126 (11)	0.0039 (12)
C8'	0.0370 (16)	0.0394 (16)	0.0185 (14)	−0.0004 (12)	0.0079 (12)	−0.0030 (11)
C8a	0.0289 (13)	0.0289 (14)	0.0205 (13)	0.0038 (11)	0.0061 (10)	0.0035 (11)
C8a'	0.0239 (14)	0.0377 (15)	0.0136 (12)	−0.0026 (11)	0.0041 (10)	−0.0002 (11)
C9	0.0254 (13)	0.0307 (14)	0.0120 (12)	0.0028 (10)	0.0048 (10)	−0.0012 (10)
C9'	0.0277 (13)	0.0252 (13)	0.0129 (12)	−0.0022 (10)	0.0023 (10)	0.0035 (10)
C9a	0.0272 (14)	0.0333 (14)	0.0121 (12)	0.0022 (11)	0.0016 (10)	0.0023 (10)
C9a'	0.0266 (13)	0.0269 (13)	0.0215 (13)	−0.0035 (11)	0.0065 (10)	−0.0011 (11)
C10	0.0509 (18)	0.0345 (15)	0.0207 (14)	0.0005 (13)	0.0076 (12)	−0.0071 (12)
C10'	0.0373 (16)	0.0395 (16)	0.0367 (17)	−0.0002 (13)	0.0123 (13)	0.0182 (13)
C10a	0.0363 (15)	0.0316 (14)	0.0274 (14)	−0.0003 (12)	0.0062 (12)	0.0015 (12)
C10a'	0.0279 (14)	0.0428 (16)	0.0191 (13)	−0.0054 (12)	0.0040 (10)	0.0073 (12)

Geometric parameters (Å, º)

S—S'	2.1089 (12)	C5—C10a	1.432 (4)
S—C9	1.776 (3)	C5'—C6'	1.364 (5)
S'—C9'	1.770 (2)	C5'—C10a'	1.446 (4)
C1—C2	1.376 (4)	C6—C7	1.401 (5)
C1'—C2'	1.352 (4)	C6'—C7'	1.395 (5)
C1—C9a	1.419 (4)	C7—C8	1.358 (4)
C1'—C9a'	1.436 (4)	C7'—C8'	1.379 (4)
C2—C3	1.404 (4)	C8—C8a	1.441 (4)
C2'—C3'	1.410 (5)	C8'—C8a'	1.429 (4)
C3—C4	1.348 (5)	C8a—C9	1.401 (4)
C3'—C4'	1.364 (5)	C8a'—C9'	1.423 (4)
C4—C4a	1.444 (4)	C8a—C10a	1.424 (4)
C4'—C4a'	1.426 (4)	C8a'—C10a'	1.424 (4)
C4a—C9a	1.423 (4)	C9—C9a	1.429 (3)
C4a'—C9a'	1.433 (4)	C9'—C9a'	1.405 (4)
C4a—C10	1.389 (4)	C10—C10a	1.408 (4)
C4a'—C10'	1.406 (4)	C10'—C10a'	1.385 (4)
C5—C6	1.364 (5)
C9—S—S'	102.45 (9)	C9—C8a—C8	123.9 (2)
C9'—S'—S	102.67 (9)	C10a—C8a—C8	117.1 (2)
C2—C1—C9a	120.9 (3)	C10a'—C8a'—C9'	118.3 (2)
C2'—C1'—C9a'	122.0 (3)	C10a'—C8a'—C8'	118.4 (2)
C1—C2—C3	120.6 (3)	C9'—C8a'—C8'	123.2 (2)
C1'—C2'—C3'	120.9 (3)	C8a—C9—C9a	121.8 (2)
C4—C3—C2	120.3 (3)	C8a—C9—S	118.76 (19)
C4'—C3'—C2'	119.5 (3)	C8a'—C9'—S'	119.6 (2)
C3—C4—C4a	121.3 (3)	C9a—C9—S	119.5 (2)
C3'—C4'—C4a'	121.5 (3)	C9a'—C9'—S'	118.62 (19)
C10—C4a—C9a	120.1 (2)	C9a'—C9'—C8a'	121.7 (2)
C10—C4a—C4	121.6 (3)	C1—C9a—C4a	118.6 (2)
C9a—C4a—C4	118.3 (3)	C1—C9a—C9	123.4 (2)
C10'—C4a'—C4'	122.0 (3)	C4a—C9a—C9	118.0 (2)
C10'—C4a'—C9a'	119.0 (3)	C9'—C9a'—C4a'	118.7 (2)
C4'—C4a'—C9a'	119.1 (3)	C9'—C9a'—C1'	124.3 (2)
C6—C5—C10a	120.9 (3)	C4a'—C9a'—C1'	117.0 (2)
C6'—C5'—C10a'	120.8 (3)	C4a—C10—C10a	121.8 (3)
C5—C6—C7	119.8 (3)	C10a'—C10'—C4a'	122.2 (3)
C5'—C6'—C7'	120.1 (3)	C10—C10a—C8a	119.2 (3)
C8—C7—C6	121.5 (3)	C10—C10a—C5	121.2 (3)
C8'—C7'—C6'	121.5 (3)	C8a—C10a—C5	119.6 (3)
C7—C8—C8a	121.1 (3)	C10'—C10a'—C8a'	119.9 (2)
C7'—C8'—C8a'	120.3 (3)	C10'—C10a'—C5'	121.3 (3)
C9—C8a—C10a	119.0 (2)	C8a'—C10a'—C5'	118.8 (3)
C9—S—S'—C9'	76.06 (13)	C10—C4a—C9a—C9	−0.4 (4)
C9a—C1—C2—C3	−1.7 (4)	C4—C4a—C9a—C9	179.5 (2)
C9a'—C1'—C2'—C3'	0.7 (5)	C8a—C9—C9a—C1	177.7 (2)
C1—C2—C3—C4	0.6 (4)	S—C9—C9a—C1	−2.5 (4)
C1'—C2'—C3'—C4'	−2.1 (5)	C8a—C9—C9a—C4a	−2.5 (4)
C2—C3—C4—C4a	0.3 (4)	S—C9—C9a—C4a	177.29 (18)
C2'—C3'—C4'—C4a'	1.8 (5)	C8a'—C9'—C9a'—C4a'	3.8 (4)
C3—C4—C4a—C10	179.6 (3)	S'—C9'—C9a'—C4a'	−176.28 (19)
C3—C4—C4a—C9a	−0.2 (4)	C8a'—C9'—C9a'—C1'	−178.0 (2)
C3'—C4'—C4a'—C10'	−179.5 (3)	S'—C9'—C9a'—C1'	1.9 (4)
C3'—C4'—C4a'—C9a'	−0.2 (5)	C10'—C4a'—C9a'—C9'	−3.5 (4)
C10a—C5—C6—C7	0.6 (6)	C4'—C4a'—C9a'—C9'	177.2 (3)
C10a'—C5'—C6'—C7'	1.2 (4)	C10'—C4a'—C9a'—C1'	178.2 (3)
C5—C6—C7—C8	−2.0 (5)	C4'—C4a'—C9a'—C1'	−1.1 (4)
C5'—C6'—C7'—C8'	−0.5 (5)	C2'—C1'—C9a'—C9'	−177.3 (3)
C6—C7—C8—C8a	1.2 (5)	C2'—C1'—C9a'—C4a'	0.9 (4)
C6'—C7'—C8'—C8a'	−1.4 (5)	C9a—C4a—C10—C10a	1.5 (4)
C7—C8—C8a—C9	−179.6 (3)	C4—C4a—C10—C10a	−178.3 (3)
C7—C8—C8a—C10a	0.9 (4)	C4'—C4a'—C10'—C10a'	−179.8 (3)
C7'—C8'—C8a'—C10a'	2.5 (4)	C9a'—C4a'—C10'—C10a'	0.9 (4)
C7'—C8'—C8a'—C9'	−177.9 (3)	C4a—C10—C10a—C8a	0.2 (4)
C10a—C8a—C9—C9a	4.2 (4)	C4a—C10—C10a—C5	179.0 (3)
C8—C8a—C9—C9a	−175.3 (2)	C9—C8a—C10a—C10	−3.0 (4)
C10a—C8a—C9—S	−175.63 (19)	C8—C8a—C10a—C10	176.5 (3)
C8—C8a—C9—S	4.9 (4)	C9—C8a—C10a—C5	178.2 (3)
S'—S—C9—C8a	−101.0 (2)	C8—C8a—C10a—C5	−2.3 (4)
S'—S—C9—C9a	79.2 (2)	C6—C5—C10a—C10	−177.2 (3)
C10a'—C8a'—C9'—C9a'	−1.4 (4)	C6—C5—C10a—C8a	1.5 (5)
C8'—C8a'—C9'—C9a'	179.0 (2)	C4a'—C10'—C10a'—C8a'	1.6 (4)
C10a'—C8a'—C9'—S'	178.70 (19)	C4a'—C10'—C10a'—C5'	−178.3 (3)
C8'—C8a'—C9'—S'	−0.9 (4)	C9'—C8a'—C10a'—C10'	−1.3 (4)
S—S'—C9'—C9a'	−100.4 (2)	C8'—C8a'—C10a'—C10'	178.3 (3)
S—S'—C9'—C8a'	79.5 (2)	C9'—C8a'—C10a'—C5'	178.6 (2)
C2—C1—C9a—C4a	1.7 (4)	C8'—C8a'—C10a'—C5'	−1.8 (4)
C2—C1—C9a—C9	−178.5 (2)	C6'—C5'—C10a'—C10'	179.9 (3)
C10—C4a—C9a—C1	179.4 (3)	C6'—C5'—C10a'—C8a'	0.0 (4)
C4—C4a—C9a—C1	−0.8 (4)