1,1′-Sulfonyl­diimidazole

The mol­ecule of the title compound, C₆H₆N₄O₂S, possesses a pseudo-twofold rotation axis of symmetry which passes through the S atom. The mol­ecules are linked through inter­molecular C—H...O hydrogen bonds into a zigzag chain of C(5) graph-set motif along the b axis. Along the a axis, the chains are cross-linked through π–π stacking inter­actions between two symmetry-related imidazole rings [centroid-to-centroid distance = 3.667 (2) Å] and by C—H...π inter­actions involving the π system of the other imidazole ring. These inter­actions lead to the formation of a layer parallel to the ab plane.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.035
• wR factor = 0.080
• Data-to-parameter ratio = 12.3

checkCIF/PLATON results

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Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
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S1. Comment

1,1'-Sulfonyldiimidazole is a potent drug belonging to the 'sulfa' family. Also, units containing diimidazole moiety have been incorporated in the synthesis of organic polymers and macrocylic complexes (Elmer et al., 1993; Lehn et al., 1989). As part of a systematic study of the stereochemistry of 'sulfa' drugs (Patel et al., 2001) in different chemicals as well as crystallographic environments, we have investigated the crystal and molecular structure of 1,1'-sulfonyldiimidazole.

The title molecule (Fig. 1) possesses an internal twofold symmetry. The two halves across sulfur is related by a pseudo-twofold axis with direction cosines 0.883, -0.467 and -0.046 (Hepperle, 2001). The rotation axis passes through the sulfur atom. The r.m.s. deviation on superposition about the axis is as low as 0.033 Å. The lengths of the symmetry (pseudo) related bonds such as C4—N3 and C1—N1, C5—N4 and C2—N2, S—N1 and S—N3, and C3—N2 and C6—N4 are similar (Table 1). The C3—N2 and C6—N4 bond lengths are shorter than the usual double bond observed in similar structures (Secondo et al., 1996; Ülkü et al., 1997). Bond angles about symmetry (pseudo) related atoms C2 and C5, and N2 and N4 are similar. The stereochemistry around sulfur, as usual in sulfonamides (Patel et al., 2001; Bettinetti & Sardone, 1997) is a distorted tetrahedron: the angles vary from 104.54 (11)° [N3—S—N1] to 124.00 (12)° [O1—S—O2]. Non-bonded contact distances and the molecular geometry around sulfur are very well comparable to those of 4,4'-diaminodiphenylsulfone, a very similar structure where the sulfide bridges two phenyl rings (Tiwari & Singh, 1982). The best planes of the two planar five-membered imidazole rings are inclined at 75.05 (17)° to each other.

Unlike in other imidazole derivatives (Blaton et al., 1979a, 1979b; Jones et al., 1996) none of the imidazolidine N-atoms are involved in any conventional hydrogen bonding interactions. However, the intermolecular interactions responding to the structure stability are relatively weak C—H···O hydrogen bonds, C—H···π and π···π interactions as usual for an aromatic molecule (Desiraju et al., 1989; Hunter & Sanders, 1990; Patel et al., 2007). The molecules are linked through intermolecular C6—H6···O1ⁱ hydrogen bonds into a zigzag chain of C5 graph set motif along the b axis (Fig. 2) (Bernstein et al., 1995). Along the a axis, the chains are cross-linked through π-π stacking interactions between two symmetry related imidazole rings, with a Cg2···Cg2ⁱⁱⁱ distance of 3.667 (2) Å [Cg2 is the N3/C4/C5/N4/C6 ring centroid and symmetry code: (iii) 1/2 + x, y, 3/2 - z], and C—H···π interactions involving the C5—H5 group and π-system of the C1/C2/N2/C3/N1 imidazole ring (centroid Cg1), The C—H···π interaction (Table 2) forms the type-III geometry according to the classification of Malone et al. (1997). These interactions lead to the formation of a layer parallel to the ab plane. The layers are arranged in such a way that the molecules are arranged sinusoidally along the c axis (Fig. 2).

Related literature

For general background, see: Elmer & Collier (1993); Lehn et al. (1989). For pseduo-symmetry analysis, see: Hepperle (2001). For related structures, see: Bettinetti & Sardone (1997); Blaton et al. (1979a,b); Jones et al. (1996); Malone et al. (1997); Patel et al. (2001, 2007); Secondo et al. (1996); Tiwari & Singh (1982); Ülkü et al. (1997). For hydrogen bonding, see: Hunter & Sanders (1990); Desiraju & Gavezzotti (1989); Bernstein et al. (1995).

S2. Experimental

The title compound was obtained from Sigma–Aldrich in pure powder form. Thin platy crystals of the compound were obtained from ethanol at room temperature. The crystal density was measured by flotation using mixture of benzene and carbon tetrachloride.

S3. Refinement

The H atoms were positioned geometrically (C—H = 0.93 Å) and refined as riding with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software; data reduction: NRCVAX (Gabe et al., 1989); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids.
	Fig. 2. The molecular packing diagram as seen along the a axis. π-π interactions are shown as solid lines, C—H···π interaction as double dashed lines and C—H···O interaction as dashed lines. H atoms not involved in interactions have been omitted.

1,1' sulfonyldiimidazole

Crystal data

C6H6N4O2S	F(000) = 816
Mr = 198.21	Dx = 1.590 Mg m^−3 Dm = 1.557 Mg m^−3 Dm measured by flotation method
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 25 reflections
a = 7.285 (2) Å	θ = 25–35°
b = 11.012 (4) Å	µ = 0.36 mm^−1
c = 20.646 (3) Å	T = 293 K
V = 1656.3 (8) Å^3	Plate, colourless
Z = 8	0.12 × 0.10 × 0.05 mm

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.000
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 3.4°
Graphite monochromator	h = 0→8
ω/2θ scans	k = −12→0
1459 measured reflections	l = 0→24
1459 independent reflections	3 standard reflections every 60 min
1064 reflections with I > 2σ(I)	intensity decay: 1%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.035	H-atom parameters constrained
wR(F^2) = 0.081	w = 1/[σ^2(Fo^2) + (0.028P)^2 + 0.9166P] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max = 0.001
1459 reflections	Δρmax = 0.19 e Å^−3
119 parameters	Δρmin = −0.26 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001Fc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0087 (7)

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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	0.66304 (8)	0.88695 (5)	0.61462 (3)	0.0380 (2)
O1	0.7673 (3)	0.99405 (16)	0.62217 (9)	0.0528 (6)
O2	0.7212 (3)	0.78547 (15)	0.57839 (8)	0.0538 (7)
N1	0.4613 (3)	0.92839 (16)	0.58525 (9)	0.0373 (7)
N2	0.2174 (3)	1.0421 (2)	0.56562 (13)	0.0606 (9)
N3	0.6173 (3)	0.83646 (17)	0.68836 (9)	0.0352 (6)
N4	0.5471 (3)	0.7087 (2)	0.76714 (11)	0.0556 (9)
C1	0.3395 (4)	0.8570 (2)	0.55011 (12)	0.0447 (9)
C2	0.1954 (4)	0.9279 (2)	0.53849 (13)	0.0509 (10)
C3	0.3767 (4)	1.0391 (2)	0.59317 (15)	0.0566 (10)
C4	0.6300 (3)	0.9021 (2)	0.74563 (12)	0.0459 (9)
C5	0.5877 (4)	0.8224 (3)	0.79227 (13)	0.0533 (10)
C6	0.5660 (4)	0.7203 (2)	0.70536 (13)	0.0476 (9)
H1	0.35530	0.77670	0.53740	0.0540*
H2	0.09260	0.90380	0.51510	0.0610*
H3	0.42790	1.10400	0.61560	0.0680*
H4	0.66100	0.98350	0.75050	0.0550*
H5	0.58590	0.84100	0.83620	0.0640*
H6	0.54740	0.65770	0.67580	0.0570*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S	0.0395 (3)	0.0406 (3)	0.0338 (3)	0.0000 (3)	0.0020 (3)	0.0011 (3)
O1	0.0503 (11)	0.0515 (10)	0.0567 (11)	−0.0169 (9)	−0.0052 (10)	0.0087 (9)
O2	0.0622 (13)	0.0561 (11)	0.0431 (10)	0.0158 (10)	0.0105 (9)	−0.0083 (9)
N1	0.0463 (13)	0.0318 (10)	0.0338 (11)	0.0018 (9)	−0.0060 (10)	−0.0020 (8)
N2	0.0603 (16)	0.0463 (14)	0.0753 (17)	0.0095 (12)	−0.0191 (14)	−0.0001 (12)
N3	0.0395 (12)	0.0344 (11)	0.0317 (10)	0.0035 (9)	0.0011 (9)	0.0006 (8)
N4	0.0567 (16)	0.0605 (15)	0.0496 (15)	0.0051 (12)	0.0048 (12)	0.0164 (12)
C1	0.0572 (17)	0.0372 (13)	0.0397 (14)	−0.0036 (13)	−0.0084 (13)	−0.0079 (11)
C2	0.0546 (18)	0.0499 (16)	0.0483 (16)	−0.0083 (14)	−0.0146 (13)	0.0024 (13)
C3	0.066 (2)	0.0326 (14)	0.0711 (19)	0.0046 (13)	−0.0187 (16)	−0.0082 (13)
C4	0.0503 (16)	0.0466 (15)	0.0407 (14)	0.0047 (12)	0.0002 (12)	−0.0088 (12)
C5	0.0494 (17)	0.078 (2)	0.0325 (14)	0.0094 (16)	0.0016 (12)	0.0002 (14)
C6	0.0539 (17)	0.0374 (15)	0.0516 (17)	0.0045 (12)	0.0029 (14)	0.0052 (12)

Geometric parameters (Å, º)

S—O1	1.411 (2)	N4—C5	1.387 (4)
S—O2	1.4099 (19)	N4—C6	1.289 (4)
S—N1	1.654 (2)	C1—C2	1.330 (4)
S—N3	1.655 (2)	C4—C5	1.339 (4)
N1—C1	1.390 (3)	C1—H1	0.93
N1—C3	1.376 (3)	C2—H2	0.93
N2—C2	1.386 (3)	C3—H3	0.93
N2—C3	1.293 (4)	C4—H4	0.93
N3—C4	1.389 (3)	C5—H5	0.93
N3—C6	1.378 (3)	C6—H6	0.93
O1···C6^i	3.261 (3)	C6···O1^ix	3.261 (3)
O2···C2^ii	3.373 (3)	C1···H5^viii	2.9900
O2···C1^ii	3.200 (3)	C2···H2^iv	3.0100
O1···H4	2.7600	C2···H5^viii	2.8700
O1···H3	2.7600	C5···H3^v	3.0700
O1···H6^i	2.5100	H1···O2	2.8000
O2···H6	2.7600	H1···O2^vi	2.6700
O2···H1	2.8000	H1···N2^x	2.7000
O2···H1^ii	2.6700	H2···N2^iv	2.8700
N1···N2	2.211 (3)	H2···C2^iv	3.0100
N2···N1	2.211 (3)	H2···H2^iv	2.5900
N3···N4	2.211 (3)	H3···O1	2.7600
N4···N3	2.211 (3)	H3···N4^xi	2.6900
N2···H1^iii	2.7000	H3···C5^xi	3.0700
N2···H2^iv	2.8700	H4···O1	2.7600
N4···H3^v	2.6900	H4···N4^xi	2.9300
N4···H4^v	2.9300	H5···C1^vii	2.9900
C1···O2^vi	3.200 (3)	H5···C2^vii	2.8700
C2···O2^vi	3.373 (3)	H6···O2	2.7600
C4···C5^vii	3.536 (4)	H6···O1^ix	2.5100
C5···C4^viii	3.536 (4)
O1—S—O2	124.00 (12)	N1—C3—N2	111.9 (2)
O1—S—N1	106.74 (11)	N3—C4—C5	104.8 (2)
O1—S—N3	106.71 (11)	N4—C5—C4	111.8 (2)
O2—S—N1	106.93 (11)	N3—C6—N4	111.9 (2)
O2—S—N3	106.40 (10)	N1—C1—H1	127.00
N1—S—N3	104.54 (11)	C2—C1—H1	127.00
S—N1—C1	127.05 (16)	N2—C2—H2	124.00
S—N1—C3	126.79 (18)	C1—C2—H2	124.00
C1—N1—C3	106.1 (2)	N1—C3—H3	124.00
C2—N2—C3	105.0 (2)	N2—C3—H3	124.00
S—N3—C4	126.51 (16)	N3—C4—H4	128.00
S—N3—C6	126.93 (17)	C5—C4—H4	128.00
C4—N3—C6	106.52 (19)	N4—C5—H5	124.00
C5—N4—C6	104.9 (2)	C4—C5—H5	124.00
N1—C1—C2	105.4 (2)	N3—C6—H6	124.00
N2—C2—C1	111.6 (2)	N4—C6—H6	124.00
O1—S—N1—C1	156.4 (2)	C3—N1—C1—C2	1.1 (3)
O1—S—N1—C3	−26.7 (2)	S—N1—C3—N2	−178.30 (19)
O2—S—N1—C1	21.8 (2)	C1—N1—C3—N2	−0.9 (3)
O2—S—N1—C3	−161.3 (2)	C3—N2—C2—C1	0.5 (3)
N3—S—N1—C1	−90.8 (2)	C2—N2—C3—N1	0.3 (3)
N3—S—N1—C3	86.1 (2)	S—N3—C4—C5	−177.4 (2)
O1—S—N3—C4	17.1 (2)	C6—N3—C4—C5	0.4 (3)
O1—S—N3—C6	−160.3 (2)	S—N3—C6—N4	177.50 (19)
O2—S—N3—C4	151.3 (2)	C4—N3—C6—N4	−0.3 (3)
O2—S—N3—C6	−26.1 (3)	C6—N4—C5—C4	0.3 (3)
N1—S—N3—C4	−95.8 (2)	C5—N4—C6—N3	0.0 (3)
N1—S—N3—C6	86.9 (2)	N1—C1—C2—N2	−1.0 (3)
S—N1—C1—C2	178.51 (18)	N3—C4—C5—N4	−0.5 (3)

Symmetry codes: (i) −x+3/2, y+1/2, z; (ii) x+1/2, −y+3/2, −z+1; (iii) −x+1/2, y+1/2, z; (iv) −x, −y+2, −z+1; (v) −x+1, y−1/2, −z+3/2; (vi) x−1/2, −y+3/2, −z+1; (vii) x+1/2, y, −z+3/2; (viii) x−1/2, y, −z+3/2; (ix) −x+3/2, y−1/2, z; (x) −x+1/2, y−1/2, z; (xi) −x+1, y+1/2, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O1^ix	0.93	2.51	3.261 (3)	138
C5—H5···Cg1^vii	0.93	2.93	3.684 (3)	139 (3)

Symmetry codes: (vii) x+1/2, y, −z+3/2; (ix) −x+3/2, y−1/2, z.