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The structure of the title compound, C14H10O4S2, comprises two 2-benzoic acid thiol­ate derivatives linked by an S-S di­sulfide bridge. The compound, which crystallizes in the space group C2/c, contains one and a half mol­ecules in the asymmetric unit and 12 mol­ecules in the unit cell. The di­sulfides are oriented with their rings rotated with respect to one another by dihedral angles of 74.9 (8) and 77.7 (6)°. The material packs in zigzag perpendicular columns whose arrangement is based on an apparent preference for hydrogen bonding between protonated acid moieties, whilst there is also evidence of a ring-stacking arrangement.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803017306/om6162sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803017306/om6162Isup2.hkl
Contains datablock I

CCDC reference: 222897

Key indicators

  • Single-crystal X-ray study
  • T = 250 K
  • Mean [sigma](C-C) = 0.004 Å
  • R factor = 0.056
  • wR factor = 0.137
  • Data-to-parameter ratio = 14.7

checkCIF/PLATON results

No syntax errors found



Alert level B PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full Low ....... 0.99 PLAT601_ALERT_2_B Structure Contains Solvent Accessible VOIDS of . 117.00 A   3
Alert level C PLAT250_ALERT_2_C Large U3/U1 ratio for average U(i,j) tensor .... 2.02 PLAT250_ALERT_2_C Large U3/U1 ratio for average U(i,j) tensor .... 2.39
0 ALERT level A = In general: serious problem 2 ALERT level B = Potentially serious problem 2 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 3 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

The deprotonated dianion of the ligand species given in the title, has been widely used in the synthesis of metal-containing complexes, yet the commonly accepted routes towards its preparation involve ring-opening reactions using mixed starting materials. In an attempt to complex the commercially available organic ligand thiosalicylic acid [C6H4(SH)(CO2H)-1,2], (II), with stoichiometric amounts of silver from silver acetate starting material under hydrothermal conditions, we were instead successful in preparing large quantities of colourless crystalline 2,2'-disulfanyldibenzoic acid, (I). We therefore present the structural data for (I), as obtained via an unexpected route.

The asymmetric unit of (I), as depicted in Fig. 1, is quite unusual since there are three S atoms present in forming one and a half dimers of the original thiosalicylic acid, none of which are associated with any special symmetry. Hence, there are two sets of (I) present in the unit cell (Z = 12), each defined by unique geometries since the S3 fragment and its symmetry-equivalent (S3A) form a symmetrical dimer, whereas the S1—S2 moiety is slightly asymmetric. The aryl rings are twisted with respect to one another, showing dihedral angles of 74.9 (8)° (S1—S2) and 77.7 (6)° (S3—S3A), which were defined based upon the planes of each phenyl ring with respect to the other. The bond lengths in (I) are in agreement with accepted literature values. The disulfide bridges were found to be 2.045 (1) and 2.043 (1) Å for S1—S2 and S3—S3A, respectively, while the average S—C bond distance is 1.781 (3) Å. All C atoms present in the aromatic rings have similar C—C distances, the average of which was calculated to be 1.388 (5) Å and the average ortho-C atom to carboxyl C atom C—C bond length is 1.476 (4) Å. Both carboxylic acid moieties are protonated in (I), conforming to a sensible neutral product. Acidic protons were located in the structural refinement along with all aryl H atoms and were allowed to refine freely.

The macrostructure of (I) takes the form of a relatively open-packed array of disulfide molecules, arranged in a pseudo-orthogonal manner owing to the magnitude of the dihedral angles quoted above. Ligands are aligned in planes which run along the crystallographic c axis, as shown in Fig. 2. This allows for favourable hydrogen-bonding interactions to be formed between carboxylic acid groups on neighbouring molecules, roughly along the ac bisector. Hydrogen-bonding distances were found to be 1.735 (4) and 1.856 (4) Å for the S1—S2-containing molecule, and 1.814 Å in the S3—S3A counterpart. All carboxylic acid groups lie in the plane of their parent ring and the network of these intermolecular contacts which arises is illustrated in Fig. 3, where molecules are plotted as they would be viewed approximately along the [103] vector. Although there is evidence of alignment of ligand rings between layers when the lattice is viewed in this geometry, this is unlikely to be governed by π-stacking interactions since the inter-ring separation distances for which are all in excess of 4.4 Å. There are four voids of volume 117 Å3 within the unit cell. There are no significant peaks in the difference map falling in these regions and the use of the SQUEEZE utility in PLATON (Spek, 2003) to account for electron density within the voids yielded a significantly worse refinement than was originally obtained. In addition, any solvent water molecules in the lattice would be expected to be located near to the carboxylic acid groups so as to maximize their hydrogen bonding. We see no evidence for solvent in this area.

Experimental top

Miligram quantities of (I) were prepared under hydrothermal conditions using a stainless-steel autoclave purchased from the Parr Corporation, Illinois, and fitted with a 23 ml Teflon liner. Silver acetate (1.0 mmol) was heated with thiosalicylic acid (1.0 mmol) in water (10 ml) at 473 K over 18 h and cooled to room temperature over a further 5 h. Compound (I) was obtained at 72% yield and isolated as large colourless blocks.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXTL (Sheldrick, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. The asymmetric unit of (I), showing one complete molecule and one half molecule drawn as displacement ellipsoids drawn at the 30% probability level.
[Figure 2] Fig. 2. Packing diagram of the unit cell of (I), viewed in the ab plane.
[Figure 3] Fig. 3. Projection of (I) roughly along the [103] vector, showing hydrogen-bonding contacts as dashed red lines.
2,2'-disulfanyldibenzoic acid top
Crystal data top
C14H10O4S2F(000) = 1896
Mr = 306.34Dx = 1.429 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.7107 Å
Hall symbol: -C 2ycCell parameters from 21148 reflections
a = 16.4457 (5) Åθ = 1.0–27.5°
b = 12.8087 (4) ŵ = 0.38 mm1
c = 20.9540 (8) ÅT = 250 K
β = 104.5589 (13)°Block, colourless
V = 4272.2 (2) Å30.18 × 0.18 × 0.12 mm
Z = 12
Data collection top
Nonius KappaCCD
diffractometer
4864 independent reflections
Radiation source: fine-focus sealed tube2674 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.058
Thin–slice ω and ϕ scansθmax = 27.5°, θmin = 3.6°
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
h = 2120
Tmin = 0.886, Tmax = 0.955k = 1616
14048 measured reflectionsl = 1627
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.056Hydrogen site location: difference Fourier map
wR(F2) = 0.137All H-atom parameters refined
S = 1.02 w = 1/[σ2(Fo2) + (0.049P)2 + 3.1475P]
where P = (Fo2 + 2Fc2)/3
4864 reflections(Δ/σ)max < 0.001
331 parametersΔρmax = 0.34 e Å3
0 restraintsΔρmin = 0.31 e Å3
Crystal data top
C14H10O4S2V = 4272.2 (2) Å3
Mr = 306.34Z = 12
Monoclinic, C2/cMo Kα radiation
a = 16.4457 (5) ŵ = 0.38 mm1
b = 12.8087 (4) ÅT = 250 K
c = 20.9540 (8) Å0.18 × 0.18 × 0.12 mm
β = 104.5589 (13)°
Data collection top
Nonius KappaCCD
diffractometer
4864 independent reflections
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
2674 reflections with I > 2σ(I)
Tmin = 0.886, Tmax = 0.955Rint = 0.058
14048 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0560 restraints
wR(F2) = 0.137All H-atom parameters refined
S = 1.02Δρmax = 0.34 e Å3
4864 reflectionsΔρmin = 0.31 e Å3
331 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
S10.23444 (5)0.94198 (6)0.21494 (3)0.0505 (2)
S20.24576 (5)0.93438 (6)0.12008 (3)0.0542 (2)
S30.00485 (5)0.93924 (5)0.29765 (3)0.0455 (2)
O10.24168 (13)0.98726 (16)0.34208 (9)0.0556 (5)
O20.32969 (15)0.91987 (18)0.43106 (10)0.0666 (7)
H2A0.302 (2)0.965 (3)0.4511 (19)0.095 (13)*
O30.24830 (15)0.95611 (17)0.00555 (10)0.0624 (6)
O40.16774 (16)0.87804 (19)0.09300 (10)0.0645 (7)
H4A0.194 (3)0.915 (3)0.113 (2)0.108 (16)*
O50.00161 (13)0.97298 (15)0.42435 (9)0.0537 (5)
O60.08030 (15)0.89745 (19)0.51192 (9)0.0639 (7)
H6A0.051 (2)0.937 (3)0.5301 (19)0.083 (12)*
C10.30723 (17)0.8477 (2)0.25890 (13)0.0421 (7)
C20.33111 (17)0.8483 (2)0.32811 (13)0.0427 (7)
C30.3867 (2)0.7723 (3)0.36144 (16)0.0577 (9)
H30.4034 (19)0.774 (2)0.4057 (16)0.066 (10)*
C40.4178 (2)0.6959 (3)0.32776 (16)0.0666 (10)
H40.4558 (19)0.645 (2)0.3526 (15)0.070 (10)*
C50.3939 (2)0.6956 (3)0.26007 (17)0.0625 (9)
H50.4128 (18)0.642 (2)0.2355 (15)0.065 (9)*
C60.3399 (2)0.7705 (2)0.22543 (15)0.0536 (8)
H60.3218 (18)0.768 (2)0.1771 (15)0.064 (9)*
C70.29654 (19)0.9248 (2)0.36681 (13)0.0446 (7)
C80.17720 (17)0.8330 (2)0.08095 (13)0.0421 (7)
C90.15805 (16)0.8209 (2)0.01161 (13)0.0406 (6)
C100.1041 (2)0.7427 (2)0.01827 (17)0.0546 (8)
H100.0927 (18)0.736 (2)0.0658 (16)0.060 (9)*
C110.0687 (2)0.6746 (3)0.01881 (18)0.0619 (9)
H110.0290 (19)0.624 (2)0.0026 (15)0.064 (10)*
C120.0880 (2)0.6858 (3)0.08631 (17)0.0584 (8)
H120.0628 (15)0.6373 (19)0.1114 (13)0.042 (7)*
C130.1413 (2)0.7631 (2)0.11703 (16)0.0492 (7)
H130.1578 (17)0.769 (2)0.1614 (14)0.050 (8)*
C140.19567 (18)0.8912 (2)0.02913 (13)0.0428 (7)
C150.06736 (16)0.84293 (19)0.33913 (12)0.0382 (6)
C160.08841 (16)0.83665 (19)0.40829 (12)0.0373 (6)
C170.14464 (19)0.7608 (2)0.43978 (15)0.0511 (8)
H170.1571 (18)0.755 (2)0.4838 (15)0.060 (9)*
C180.1798 (2)0.6904 (3)0.40443 (16)0.0608 (9)
H180.216 (2)0.640 (3)0.4275 (16)0.079 (11)*
C190.1584 (2)0.6956 (3)0.33696 (16)0.0580 (8)
H190.1853 (18)0.645 (2)0.3109 (14)0.063 (9)*
C200.10278 (19)0.7703 (2)0.30447 (15)0.0478 (7)
H200.0872 (17)0.775 (2)0.2602 (15)0.053 (8)*
C210.05148 (17)0.9085 (2)0.44829 (12)0.0377 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0721 (5)0.0522 (4)0.0273 (4)0.0087 (4)0.0130 (3)0.0037 (3)
S20.0805 (6)0.0555 (5)0.0270 (4)0.0090 (4)0.0141 (4)0.0031 (3)
S30.0679 (5)0.0464 (4)0.0227 (3)0.0067 (4)0.0126 (3)0.0002 (3)
O10.0749 (14)0.0616 (13)0.0298 (11)0.0140 (12)0.0122 (10)0.0022 (9)
O20.0921 (17)0.0753 (15)0.0289 (11)0.0252 (13)0.0089 (11)0.0047 (10)
O30.0871 (16)0.0688 (14)0.0327 (11)0.0191 (13)0.0177 (11)0.0023 (10)
O40.0883 (17)0.0782 (15)0.0262 (11)0.0181 (13)0.0126 (11)0.0011 (11)
O50.0760 (14)0.0605 (12)0.0257 (10)0.0168 (11)0.0150 (10)0.0005 (9)
O60.0845 (17)0.0824 (16)0.0224 (11)0.0279 (13)0.0092 (11)0.0048 (10)
C10.0510 (17)0.0467 (16)0.0292 (14)0.0010 (13)0.0111 (13)0.0017 (12)
C20.0509 (17)0.0500 (16)0.0272 (14)0.0002 (14)0.0101 (13)0.0019 (12)
C30.072 (2)0.068 (2)0.0289 (17)0.0095 (18)0.0058 (16)0.0005 (16)
C40.086 (3)0.070 (2)0.042 (2)0.031 (2)0.0105 (18)0.0018 (17)
C50.078 (2)0.065 (2)0.045 (2)0.0205 (19)0.0156 (17)0.0072 (17)
C60.067 (2)0.0629 (19)0.0321 (17)0.0105 (17)0.0139 (16)0.0027 (15)
C70.0572 (19)0.0500 (17)0.0275 (15)0.0018 (15)0.0124 (13)0.0008 (13)
C80.0473 (17)0.0456 (15)0.0344 (16)0.0081 (13)0.0119 (13)0.0053 (12)
C90.0408 (15)0.0472 (15)0.0327 (15)0.0111 (13)0.0075 (12)0.0027 (12)
C100.057 (2)0.062 (2)0.0427 (19)0.0005 (16)0.0093 (16)0.0005 (16)
C110.062 (2)0.059 (2)0.062 (2)0.0125 (18)0.0108 (18)0.0045 (17)
C120.063 (2)0.061 (2)0.055 (2)0.0006 (17)0.0211 (17)0.0101 (17)
C130.0573 (19)0.0560 (18)0.0348 (18)0.0029 (16)0.0129 (15)0.0046 (15)
C140.0529 (18)0.0463 (16)0.0300 (15)0.0122 (14)0.0116 (13)0.0035 (13)
C150.0486 (16)0.0402 (14)0.0266 (14)0.0043 (12)0.0107 (12)0.0015 (11)
C160.0432 (15)0.0409 (14)0.0275 (14)0.0054 (12)0.0081 (12)0.0023 (11)
C170.060 (2)0.0613 (19)0.0290 (16)0.0044 (16)0.0057 (15)0.0027 (15)
C180.075 (2)0.062 (2)0.0428 (19)0.0195 (18)0.0103 (17)0.0002 (16)
C190.071 (2)0.0579 (19)0.048 (2)0.0160 (17)0.0200 (17)0.0043 (16)
C200.065 (2)0.0527 (17)0.0276 (16)0.0040 (15)0.0156 (15)0.0020 (14)
C210.0476 (17)0.0404 (15)0.0256 (14)0.0049 (13)0.0100 (12)0.0005 (11)
Geometric parameters (Å, º) top
S1—C11.785 (3)C6—H60.98 (3)
S1—S22.0449 (10)C8—C131.396 (4)
S2—C81.779 (3)C8—C91.416 (4)
S3—C151.780 (3)C9—C101.380 (4)
S3—S3i2.0431 (13)C9—C141.479 (4)
O1—C71.219 (3)C10—C111.389 (5)
O2—C71.321 (3)C10—H100.97 (3)
O2—H2A0.91 (4)C11—C121.377 (4)
O3—C141.212 (3)C11—H110.93 (3)
O4—C141.312 (3)C12—C131.371 (4)
O4—H4A0.82 (4)C12—H120.97 (3)
O5—C211.215 (3)C13—H130.90 (3)
O6—C211.306 (3)C15—C201.395 (4)
O6—H6A0.85 (4)C15—C161.405 (3)
C1—C61.396 (4)C16—C171.389 (4)
C1—C21.404 (3)C16—C211.475 (4)
C2—C31.397 (4)C17—C181.382 (4)
C2—C71.474 (4)C17—H170.90 (3)
C3—C41.378 (4)C18—C191.370 (4)
C3—H30.90 (3)C18—H180.93 (3)
C4—C51.373 (4)C19—C201.379 (4)
C4—H40.96 (3)C19—H191.01 (3)
C5—C61.382 (4)C20—H200.90 (3)
C5—H50.96 (3)
C1—S1—S2104.85 (9)C11—C10—H10121.4 (17)
C8—S2—S1106.31 (9)C12—C11—C10119.3 (3)
C15—S3—S3i105.72 (9)C12—C11—H11114.1 (19)
C7—O2—H2A108 (2)C10—C11—H11126.4 (19)
C14—O4—H4A111 (3)C13—C12—C11120.8 (3)
C21—O6—H6A107 (2)C13—C12—H12121.1 (16)
C6—C1—C2118.7 (3)C11—C12—H12118.1 (16)
C6—C1—S1120.9 (2)C12—C13—C8121.2 (3)
C2—C1—S1120.4 (2)C12—C13—H13122.2 (18)
C3—C2—C1119.4 (3)C8—C13—H13116.5 (18)
C3—C2—C7118.9 (3)O3—C14—O4122.3 (3)
C1—C2—C7121.7 (2)O3—C14—C9122.8 (2)
C4—C3—C2121.3 (3)O4—C14—C9114.9 (3)
C4—C3—H3119 (2)C20—C15—C16118.2 (2)
C2—C3—H3120 (2)C20—C15—S3121.5 (2)
C5—C4—C3118.9 (3)C16—C15—S3120.3 (2)
C5—C4—H4122.5 (19)C17—C16—C15119.5 (2)
C3—C4—H4118.5 (19)C17—C16—C21119.1 (2)
C4—C5—C6121.3 (3)C15—C16—C21121.4 (2)
C4—C5—H5120.6 (18)C18—C17—C16121.3 (3)
C6—C5—H5118.0 (18)C18—C17—H17118.5 (19)
C5—C6—C1120.3 (3)C16—C17—H17120.1 (19)
C5—C6—H6120.6 (17)C19—C18—C17119.2 (3)
C1—C6—H6119.0 (17)C19—C18—H18122 (2)
O1—C7—O2122.4 (3)C17—C18—H18118 (2)
O1—C7—C2123.3 (2)C18—C19—C20120.6 (3)
O2—C7—C2114.3 (3)C18—C19—H19119.4 (17)
C13—C8—C9118.0 (3)C20—C19—H19120.0 (17)
C13—C8—S2121.6 (2)C19—C20—C15121.2 (3)
C9—C8—S2120.3 (2)C19—C20—H20122.4 (18)
C10—C9—C8119.8 (3)C15—C20—H20116.5 (18)
C10—C9—C14119.6 (3)O5—C21—O6122.3 (2)
C8—C9—C14120.5 (3)O5—C21—C16123.1 (2)
C9—C10—C11120.9 (3)O6—C21—C16114.6 (3)
C9—C10—H10117.7 (17)
Symmetry code: (i) x, y, z+1/2.

Experimental details

Crystal data
Chemical formulaC14H10O4S2
Mr306.34
Crystal system, space groupMonoclinic, C2/c
Temperature (K)250
a, b, c (Å)16.4457 (5), 12.8087 (4), 20.9540 (8)
β (°) 104.5589 (13)
V3)4272.2 (2)
Z12
Radiation typeMo Kα
µ (mm1)0.38
Crystal size (mm)0.18 × 0.18 × 0.12
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionMulti-scan
(SORTAV; Blessing, 1995)
Tmin, Tmax0.886, 0.955
No. of measured, independent and
observed [I > 2σ(I)] reflections
14048, 4864, 2674
Rint0.058
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.056, 0.137, 1.02
No. of reflections4864
No. of parameters331
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.34, 0.31

Computer programs: COLLECT (Nonius, 1998), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK, SHELXTL (Sheldrick, 2000), SHELXTL.

Selected geometric parameters (Å, º) top
S1—C11.785 (3)O4—C141.312 (3)
S1—S22.0449 (10)O4—H4A0.82 (4)
S2—C81.779 (3)O5—C211.215 (3)
S3—C151.780 (3)O6—C211.306 (3)
S3—S3i2.0431 (13)O6—H6A0.85 (4)
O1—C71.219 (3)C2—C71.474 (4)
O2—C71.321 (3)C9—C141.479 (4)
O2—H2A0.91 (4)C16—C211.475 (4)
O3—C141.212 (3)
C1—S1—S2104.85 (9)C9—C8—S2120.3 (2)
C8—S2—S1106.31 (9)C10—C9—C14119.6 (3)
C15—S3—S3i105.72 (9)C8—C9—C14120.5 (3)
C7—O2—H2A108 (2)O3—C14—O4122.3 (3)
C14—O4—H4A111 (3)O3—C14—C9122.8 (2)
C21—O6—H6A107 (2)O4—C14—C9114.9 (3)
C6—C1—S1120.9 (2)C20—C15—S3121.5 (2)
C2—C1—S1120.4 (2)C16—C15—S3120.3 (2)
C3—C2—C7118.9 (3)C17—C16—C21119.1 (2)
C1—C2—C7121.7 (2)C15—C16—C21121.4 (2)
O1—C7—O2122.4 (3)O5—C21—O6122.3 (2)
O1—C7—C2123.3 (2)O5—C21—C16123.1 (2)
O2—C7—C2114.3 (3)O6—C21—C16114.6 (3)
C13—C8—S2121.6 (2)
Symmetry code: (i) x, y, z+1/2.
 

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