Buy article online - an online subscription or single-article purchase is required to access this article.
Download citation
Download citation
link to html
In crystalline thio­salicylic acid (2-mercapto­benzoic acid), C7H6O2S, the carboxyl­ic acid groups form hydrogen-bonded dimers, whereas the S—H groups form an infinite S—H...S—H...S—H hydrogen-bond chain, with an S...S distance of 3.986 (3) Å.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100005898/de1138sup1.cif
Contains datablocks salic, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100005898/de1138Isup2.hkl
Contains datablock I

CCDC reference: 147664

Comment top

Although S—H is a classical hydrogen-bonding functional group, there is surprisingly little structural information on S—H···X hydrogen bonds. Even for the most common variant, S—H···O, the published material is scarce (Allen et al., 1997). For all the other cases like S—H···S, S—H···N, S—H···Cl, S—H···Ph, etc., there are only a handful of relevant crystal structures (surveyed by Desiraju & Steiner, 1999; also see Steiner, 1998; Rozenberg et al., 1999). In this context, the crystal structure of thiosalicylic acid, (I), was determined. Initially, it was unclear which kind of hydrogen bond the S—H group would form (inter- or intramolecular S—H···O, S—H···S). \sch

The molecular structure of (I) in the crystal is shown in Figure 1. The mercapto and carboxyl groups have normal geometries [C2—S1 = 1.766 (3), S1—H1 = 1.30 (5) Å, C2—S1—H1 = 95 (2)°; O1C7 = 1.219 (4), O2—C7 = 1.306 (4) Å]. No intramolecular S—H···O hydrogen bond is formed, but the S—H group is oriented away from the carboxylic acid moiety [torsion angle C1—C2—S1—H1 = 178 (2)°]. This contrasts the oxygen analogue salicylic acid, where an intramolecular O—H···OC hydrogen bond is formed with O···O = 2.62 Å (Sundaralingam & Jensen, 1965). The molecule of (I) is significantly non-planar with the carboxylic acid group rotated 10.0 (2)° out of the aromatic plane. This way, O1 is displaced by 0.131 (5) Å from the ring plane. S1 is displaced from that plane in opposite direction by −0.016 (4) Å. The angle C1—C2—S1 is widened to 122.1 (2)°. These distortions indicate significal steric repulsion between O1 and S1 [distance 2.752 (3) Å]. When thinking about why no intramolecular hydrogen bond is formed, one must consider that S···O distances in S—H···O hydrogen bonds have been found only longer than 3.2 Å (Desiraju & Steiner, 1999). A hypothetical S—H···O interaction with an S···O separation around 2.75 Å would (if relatively linear) have an H···O distance so short that it is deep in the repulsive regime of the hydrogen-bond potential.

The hydrogen-bond scheme that is actually formed in (I) is shown in Figure 2, geometrical parameters are listed in Table 1. The carboxylic acid groups form dimers with standard geometry [O···O = 2.657 (4) Å]. The S—H groups form an infinite hydrogen-bond chain S—H···S—H···S—H in direction of the y axis with distances S···S = 3.986 (3) and H···S = 2.72 (5) Å. Since the C—S—H group has refined almost to typical neutron-diffraction geometry [e.g. S—H = 1.338 (2) Å and C—S—H = 96.9 (2)° in the neutron diffraction study of N-acetyl-l-cysteine, Takusagawa et al., 1981], the geometry in Table 1 is already realistic and normalization is unnecessary. The distances are similar as in other S—H···S hydrogen bonds between poorly activated S—H groups like in thiols and thiophenols (they can be considerably shorter between more polar S—H groups). The acceptor directionality is described by the angle H···S1—C2 = 76.1 (9)° and the torsion angle H···S1—C2—C1 = −81 (1)°, showing that the hydrogen bonds are directed at the `sides' of the C—S—H acceptors. Two weak C—H···O hydrogen bonds are also formed (Table 1).

Experimental top

Thiosalicylic acid, (I), was obtained from Aldrich, and was recrystallized from MeOH by slow evaporation of the solvent.

Refinement top

H atoms bonded to C were treated in the default riding model, the H atoms bonded to O2 and S1 were located in difference Fourier calculations and refined isotropically. All H atom displacement parameters refined to realistic values [H atoms bonded to C: 0.056–0.072 Å2; H atoms at O and S: 0.11 (1) and 0.09 (1) Å2, respectively].

Computing details top

Program(s) used to solve structure: SHELXS86 (Sheldrick, 1986); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1990); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. Molecular structure of (I). Displacement ellipsoids are drawn at the 30% probability level.
[Figure 2] Fig. 2. Section of the crystal packing illustrating the system of O—H···O and S—H···S hydrogen bonds. The S—H···S chain runs in direction of the y axis.
2-mercaptobenzoic acid top
Crystal data top
C7H6O2SF(000) = 320
Mr = 154.18Dx = 1.489 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 7.856 (7) ÅCell parameters from 34 reflections
b = 5.963 (5) Åθ = 7.2–16.2°
c = 14.940 (11) ŵ = 0.40 mm1
β = 100.69 (7)°T = 293 K
V = 687.7 (10) Å3Plate, yellow
Z = 40.25 × 0.20 × 0.03 mm
Data collection top
Stoe four circle
diffractometer
Rint = 0.043
Radiation source: fine-focus sealed tubeθmax = 27.5°, θmin = 2.6°
Graphite monochromatorh = 107
ω–scansk = 77
1692 measured reflectionsl = 1914
1580 independent reflections3 standard reflections every 90 min
1188 reflections with I > 2σ(I) intensity decay: 5%
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)] = 0.057Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.171H atoms treated by a mixture of independent and constrained refinement
S = 1.03 w = 1/[σ2(Fo2) + (0.1042P)2 + 0.1754P]
where P = (Fo2 + 2Fc2)/3
1580 reflections(Δ/σ)max < 0.001
103 parametersΔρmax = 0.53 e Å3
0 restraintsΔρmin = 0.30 e Å3
Crystal data top
C7H6O2SV = 687.7 (10) Å3
Mr = 154.18Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.856 (7) ŵ = 0.40 mm1
b = 5.963 (5) ÅT = 293 K
c = 14.940 (11) Å0.25 × 0.20 × 0.03 mm
β = 100.69 (7)°
Data collection top
Stoe four circle
diffractometer
Rint = 0.043
1692 measured reflections3 standard reflections every 90 min
1580 independent reflections intensity decay: 5%
1188 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0570 restraints
wR(F2) = 0.171H atoms treated by a mixture of independent and constrained refinement
S = 1.03Δρmax = 0.53 e Å3
1580 reflectionsΔρmin = 0.30 e Å3
103 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
S10.51689 (9)0.11696 (13)0.16353 (5)0.0462 (3)
H10.495 (6)0.301 (8)0.206 (3)0.089 (14)*
O10.5120 (3)0.2870 (4)0.07396 (16)0.0513 (6)
O20.2759 (3)0.4588 (4)0.00178 (18)0.0567 (7)
H20.355 (7)0.542 (11)0.021 (3)0.108 (18)*
C10.2377 (3)0.1588 (5)0.09739 (18)0.0364 (6)
C20.2970 (3)0.0356 (5)0.14519 (18)0.0368 (6)
C30.1783 (4)0.1685 (6)0.1799 (2)0.0495 (8)
H30.21640.29700.21290.072 (12)*
C40.0063 (4)0.1121 (6)0.1661 (2)0.0516 (8)
H40.07120.20410.18890.056 (10)*
C50.0528 (4)0.0779 (6)0.1191 (2)0.0501 (8)
H50.16940.11610.11060.065 (11)*
C60.0623 (4)0.2121 (6)0.0845 (2)0.0437 (7)
H60.02210.34050.05200.057 (10)*
C70.3548 (4)0.3061 (5)0.05711 (19)0.0400 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.0355 (4)0.0408 (5)0.0627 (5)0.0039 (3)0.0104 (3)0.0065 (3)
O10.0319 (10)0.0506 (13)0.0726 (14)0.0017 (9)0.0126 (9)0.0245 (11)
O20.0367 (11)0.0542 (14)0.0810 (17)0.0036 (10)0.0160 (11)0.0309 (12)
C10.0335 (13)0.0366 (14)0.0406 (13)0.0022 (11)0.0104 (10)0.0005 (11)
C20.0323 (13)0.0387 (14)0.0401 (13)0.0018 (11)0.0088 (10)0.0001 (11)
C30.0440 (16)0.0448 (17)0.0615 (19)0.0036 (13)0.0147 (14)0.0144 (14)
C40.0418 (16)0.056 (2)0.0611 (19)0.0086 (14)0.0199 (14)0.0111 (15)
C50.0329 (14)0.063 (2)0.0569 (18)0.0003 (13)0.0139 (12)0.0068 (15)
C60.0347 (14)0.0460 (16)0.0515 (16)0.0029 (12)0.0114 (11)0.0088 (13)
C70.0369 (14)0.0369 (14)0.0478 (15)0.0007 (12)0.0122 (11)0.0051 (12)
Geometric parameters (Å, º) top
S1—C21.766 (3)C2—C31.396 (4)
S1—H11.30 (5)C3—C41.370 (4)
O1—C71.219 (4)C3—H30.9300
O2—C71.306 (4)C4—C51.368 (5)
O2—H20.91 (6)C4—H40.9300
C1—C61.392 (4)C5—C61.377 (4)
C1—C21.395 (4)C5—H50.9300
C1—C71.478 (4)C6—H60.9300
C2—S1—H195 (2)C5—C4—H4119.6
C7—O2—H2110 (3)C3—C4—H4119.6
C6—C1—C2119.2 (3)C4—C5—C6119.3 (3)
C6—C1—C7118.9 (3)C4—C5—H5120.3
C2—C1—C7121.9 (2)C6—C5—H5120.3
C1—C2—C3118.6 (3)C5—C6—C1121.2 (3)
C1—C2—S1122.1 (2)C5—C6—H6119.4
C3—C2—S1119.2 (2)C1—C6—H6119.4
C4—C3—C2120.9 (3)O1—C7—O2122.7 (3)
C4—C3—H3119.6O1—C7—C1122.9 (3)
C2—C3—H3119.6O2—C7—C1114.4 (3)
C5—C4—C3120.8 (3)
C6—C1—C2—C31.1 (4)C4—C5—C6—C10.7 (5)
C7—C1—C2—C3178.9 (3)C2—C1—C6—C50.8 (5)
C6—C1—C2—S1179.3 (2)C7—C1—C6—C5178.7 (3)
C7—C1—C2—S11.5 (4)C6—C1—C7—O1171.1 (3)
C1—C2—C3—C41.2 (5)C2—C1—C7—O111.1 (5)
S1—C2—C3—C4179.2 (3)C6—C1—C7—O29.0 (4)
C2—C3—C4—C51.1 (5)C2—C1—C7—O2168.8 (3)
C3—C4—C5—C60.8 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.91 (6)1.75 (6)2.657 (4)174 (5)
S1—H1···S1ii1.30 (5)2.72 (5)3.986 (3)164 (3)
C5—H5···O1iii0.932.663.584 (5)171
C6—H6···O2iv0.932.623.362 (5)137
Symmetry codes: (i) x+1, y1, z; (ii) x+1, y+1/2, z+1/2; (iii) x1, y, z; (iv) x, y1, z.

Experimental details

Crystal data
Chemical formulaC7H6O2S
Mr154.18
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)7.856 (7), 5.963 (5), 14.940 (11)
β (°) 100.69 (7)
V3)687.7 (10)
Z4
Radiation typeMo Kα
µ (mm1)0.40
Crystal size (mm)0.25 × 0.20 × 0.03
Data collection
DiffractometerStoe four circle
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
1692, 1580, 1188
Rint0.043
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.057, 0.171, 1.03
No. of reflections1580
No. of parameters103
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.53, 0.30

Computer programs: SHELXS86 (Sheldrick, 1986), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 1990), SHELXL97.

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.91 (6)1.75 (6)2.657 (4)174 (5)
S1—H1···S1ii1.30 (5)2.72 (5)3.986 (3)164 (3)
C5—H5···O1iii0.932.663.584 (5)171
C6—H6···O2iv0.932.623.362 (5)137
Symmetry codes: (i) x+1, y1, z; (ii) x+1, y+1/2, z+1/2; (iii) x1, y, z; (iv) x, y1, z.
 

Subscribe to Acta Crystallographica Section C: Structural Chemistry

The full text of this article is available to subscribers to the journal.

If you have already registered and are using a computer listed in your registration details, please email support@iucr.org for assistance.

Buy online

You may purchase this article in PDF and/or HTML formats. For purchasers in the European Community who do not have a VAT number, VAT will be added at the local rate. Payments to the IUCr are handled by WorldPay, who will accept payment by credit card in several currencies. To purchase the article, please complete the form below (fields marked * are required), and then click on `Continue'.
E-mail address* 
Repeat e-mail address* 
(for error checking) 

Format*   PDF (US $40)
   HTML (US $40)
   PDF+HTML (US $50)
In order for VAT to be shown for your country javascript needs to be enabled.

VAT number 
(non-UK EC countries only) 
Country* 
 

Terms and conditions of use
Contact us

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds