Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803017306/om6162sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803017306/om6162Isup2.hkl |
CCDC reference: 222897
Key indicators
- Single-crystal X-ray study
- T = 250 K
- Mean (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
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.
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.
C14H10O4S2 | F(000) = 1896 |
Mr = 306.34 | Dx = 1.429 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.7107 Å |
Hall symbol: -C 2yc | Cell parameters from 21148 reflections |
a = 16.4457 (5) Å | θ = 1.0–27.5° |
b = 12.8087 (4) Å | µ = 0.38 mm−1 |
c = 20.9540 (8) Å | T = 250 K |
β = 104.5589 (13)° | Block, colourless |
V = 4272.2 (2) Å3 | 0.18 × 0.18 × 0.12 mm |
Z = 12 |
Nonius KappaCCD diffractometer | 4864 independent reflections |
Radiation source: fine-focus sealed tube | 2674 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.058 |
Thin–slice ω and ϕ scans | θmax = 27.5°, θmin = 3.6° |
Absorption correction: multi-scan (SORTAV; Blessing, 1995) | h = −21→20 |
Tmin = 0.886, Tmax = 0.955 | k = −16→16 |
14048 measured reflections | l = −16→27 |
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)] = 0.056 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.137 | All 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 parameters | Δρmax = 0.34 e Å−3 |
0 restraints | Δρmin = −0.31 e Å−3 |
C14H10O4S2 | V = 4272.2 (2) Å3 |
Mr = 306.34 | Z = 12 |
Monoclinic, C2/c | Mo Kα radiation |
a = 16.4457 (5) Å | µ = 0.38 mm−1 |
b = 12.8087 (4) Å | T = 250 K |
c = 20.9540 (8) Å | 0.18 × 0.18 × 0.12 mm |
β = 104.5589 (13)° |
Nonius KappaCCD diffractometer | 4864 independent reflections |
Absorption correction: multi-scan (SORTAV; Blessing, 1995) | 2674 reflections with I > 2σ(I) |
Tmin = 0.886, Tmax = 0.955 | Rint = 0.058 |
14048 measured reflections |
R[F2 > 2σ(F2)] = 0.056 | 0 restraints |
wR(F2) = 0.137 | All H-atom parameters refined |
S = 1.02 | Δρmax = 0.34 e Å−3 |
4864 reflections | Δρmin = −0.31 e Å−3 |
331 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
S1 | 0.23444 (5) | 0.94198 (6) | 0.21494 (3) | 0.0505 (2) | |
S2 | 0.24576 (5) | 0.93438 (6) | 0.12008 (3) | 0.0542 (2) | |
S3 | −0.00485 (5) | 0.93924 (5) | 0.29765 (3) | 0.0455 (2) | |
O1 | 0.24168 (13) | 0.98726 (16) | 0.34208 (9) | 0.0556 (5) | |
O2 | 0.32969 (15) | 0.91987 (18) | 0.43106 (10) | 0.0666 (7) | |
H2A | 0.302 (2) | 0.965 (3) | 0.4511 (19) | 0.095 (13)* | |
O3 | 0.24830 (15) | 0.95611 (17) | −0.00555 (10) | 0.0624 (6) | |
O4 | 0.16774 (16) | 0.87804 (19) | −0.09300 (10) | 0.0645 (7) | |
H4A | 0.194 (3) | 0.915 (3) | −0.113 (2) | 0.108 (16)* | |
O5 | −0.00161 (13) | 0.97298 (15) | 0.42435 (9) | 0.0537 (5) | |
O6 | 0.08030 (15) | 0.89745 (19) | 0.51192 (9) | 0.0639 (7) | |
H6A | 0.051 (2) | 0.937 (3) | 0.5301 (19) | 0.083 (12)* | |
C1 | 0.30723 (17) | 0.8477 (2) | 0.25890 (13) | 0.0421 (7) | |
C2 | 0.33111 (17) | 0.8483 (2) | 0.32811 (13) | 0.0427 (7) | |
C3 | 0.3867 (2) | 0.7723 (3) | 0.36144 (16) | 0.0577 (9) | |
H3 | 0.4034 (19) | 0.774 (2) | 0.4057 (16) | 0.066 (10)* | |
C4 | 0.4178 (2) | 0.6959 (3) | 0.32776 (16) | 0.0666 (10) | |
H4 | 0.4558 (19) | 0.645 (2) | 0.3526 (15) | 0.070 (10)* | |
C5 | 0.3939 (2) | 0.6956 (3) | 0.26007 (17) | 0.0625 (9) | |
H5 | 0.4128 (18) | 0.642 (2) | 0.2355 (15) | 0.065 (9)* | |
C6 | 0.3399 (2) | 0.7705 (2) | 0.22543 (15) | 0.0536 (8) | |
H6 | 0.3218 (18) | 0.768 (2) | 0.1771 (15) | 0.064 (9)* | |
C7 | 0.29654 (19) | 0.9248 (2) | 0.36681 (13) | 0.0446 (7) | |
C8 | 0.17720 (17) | 0.8330 (2) | 0.08095 (13) | 0.0421 (7) | |
C9 | 0.15805 (16) | 0.8209 (2) | 0.01161 (13) | 0.0406 (6) | |
C10 | 0.1041 (2) | 0.7427 (2) | −0.01827 (17) | 0.0546 (8) | |
H10 | 0.0927 (18) | 0.736 (2) | −0.0658 (16) | 0.060 (9)* | |
C11 | 0.0687 (2) | 0.6746 (3) | 0.01881 (18) | 0.0619 (9) | |
H11 | 0.0290 (19) | 0.624 (2) | 0.0026 (15) | 0.064 (10)* | |
C12 | 0.0880 (2) | 0.6858 (3) | 0.08631 (17) | 0.0584 (8) | |
H12 | 0.0628 (15) | 0.6373 (19) | 0.1114 (13) | 0.042 (7)* | |
C13 | 0.1413 (2) | 0.7631 (2) | 0.11703 (16) | 0.0492 (7) | |
H13 | 0.1578 (17) | 0.769 (2) | 0.1614 (14) | 0.050 (8)* | |
C14 | 0.19567 (18) | 0.8912 (2) | −0.02913 (13) | 0.0428 (7) | |
C15 | 0.06736 (16) | 0.84293 (19) | 0.33913 (12) | 0.0382 (6) | |
C16 | 0.08841 (16) | 0.83665 (19) | 0.40829 (12) | 0.0373 (6) | |
C17 | 0.14464 (19) | 0.7608 (2) | 0.43978 (15) | 0.0511 (8) | |
H17 | 0.1571 (18) | 0.755 (2) | 0.4838 (15) | 0.060 (9)* | |
C18 | 0.1798 (2) | 0.6904 (3) | 0.40443 (16) | 0.0608 (9) | |
H18 | 0.216 (2) | 0.640 (3) | 0.4275 (16) | 0.079 (11)* | |
C19 | 0.1584 (2) | 0.6956 (3) | 0.33696 (16) | 0.0580 (8) | |
H19 | 0.1853 (18) | 0.645 (2) | 0.3109 (14) | 0.063 (9)* | |
C20 | 0.10278 (19) | 0.7703 (2) | 0.30447 (15) | 0.0478 (7) | |
H20 | 0.0872 (17) | 0.775 (2) | 0.2602 (15) | 0.053 (8)* | |
C21 | 0.05148 (17) | 0.9085 (2) | 0.44829 (12) | 0.0377 (6) |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0721 (5) | 0.0522 (4) | 0.0273 (4) | 0.0087 (4) | 0.0130 (3) | 0.0037 (3) |
S2 | 0.0805 (6) | 0.0555 (5) | 0.0270 (4) | −0.0090 (4) | 0.0141 (4) | 0.0031 (3) |
S3 | 0.0679 (5) | 0.0464 (4) | 0.0227 (3) | 0.0067 (4) | 0.0126 (3) | −0.0002 (3) |
O1 | 0.0749 (14) | 0.0616 (13) | 0.0298 (11) | 0.0140 (12) | 0.0122 (10) | −0.0022 (9) |
O2 | 0.0921 (17) | 0.0753 (15) | 0.0289 (11) | 0.0252 (13) | 0.0089 (11) | −0.0047 (10) |
O3 | 0.0871 (16) | 0.0688 (14) | 0.0327 (11) | −0.0191 (13) | 0.0177 (11) | 0.0023 (10) |
O4 | 0.0883 (17) | 0.0782 (15) | 0.0262 (11) | −0.0181 (13) | 0.0126 (11) | 0.0011 (11) |
O5 | 0.0760 (14) | 0.0605 (12) | 0.0257 (10) | 0.0168 (11) | 0.0150 (10) | −0.0005 (9) |
O6 | 0.0845 (17) | 0.0824 (16) | 0.0224 (11) | 0.0279 (13) | 0.0092 (11) | −0.0048 (10) |
C1 | 0.0510 (17) | 0.0467 (16) | 0.0292 (14) | −0.0010 (13) | 0.0111 (13) | 0.0017 (12) |
C2 | 0.0509 (17) | 0.0500 (16) | 0.0272 (14) | −0.0002 (14) | 0.0101 (13) | −0.0019 (12) |
C3 | 0.072 (2) | 0.068 (2) | 0.0289 (17) | 0.0095 (18) | 0.0058 (16) | 0.0005 (16) |
C4 | 0.086 (3) | 0.070 (2) | 0.042 (2) | 0.031 (2) | 0.0105 (18) | 0.0018 (17) |
C5 | 0.078 (2) | 0.065 (2) | 0.045 (2) | 0.0205 (19) | 0.0156 (17) | −0.0072 (17) |
C6 | 0.067 (2) | 0.0629 (19) | 0.0321 (17) | 0.0105 (17) | 0.0139 (16) | −0.0027 (15) |
C7 | 0.0572 (19) | 0.0500 (17) | 0.0275 (15) | −0.0018 (15) | 0.0124 (13) | 0.0008 (13) |
C8 | 0.0473 (17) | 0.0456 (15) | 0.0344 (16) | 0.0081 (13) | 0.0119 (13) | 0.0053 (12) |
C9 | 0.0408 (15) | 0.0472 (15) | 0.0327 (15) | 0.0111 (13) | 0.0075 (12) | 0.0027 (12) |
C10 | 0.057 (2) | 0.062 (2) | 0.0427 (19) | −0.0005 (16) | 0.0093 (16) | 0.0005 (16) |
C11 | 0.062 (2) | 0.059 (2) | 0.062 (2) | −0.0125 (18) | 0.0108 (18) | −0.0045 (17) |
C12 | 0.063 (2) | 0.061 (2) | 0.055 (2) | 0.0006 (17) | 0.0211 (17) | 0.0101 (17) |
C13 | 0.0573 (19) | 0.0560 (18) | 0.0348 (18) | 0.0029 (16) | 0.0129 (15) | 0.0046 (15) |
C14 | 0.0529 (18) | 0.0463 (16) | 0.0300 (15) | 0.0122 (14) | 0.0116 (13) | 0.0035 (13) |
C15 | 0.0486 (16) | 0.0402 (14) | 0.0266 (14) | −0.0043 (12) | 0.0107 (12) | 0.0015 (11) |
C16 | 0.0432 (15) | 0.0409 (14) | 0.0275 (14) | −0.0054 (12) | 0.0081 (12) | −0.0023 (11) |
C17 | 0.060 (2) | 0.0613 (19) | 0.0290 (16) | 0.0044 (16) | 0.0057 (15) | 0.0027 (15) |
C18 | 0.075 (2) | 0.062 (2) | 0.0428 (19) | 0.0195 (18) | 0.0103 (17) | −0.0002 (16) |
C19 | 0.071 (2) | 0.0579 (19) | 0.048 (2) | 0.0160 (17) | 0.0200 (17) | −0.0043 (16) |
C20 | 0.065 (2) | 0.0527 (17) | 0.0276 (16) | 0.0040 (15) | 0.0156 (15) | −0.0020 (14) |
C21 | 0.0476 (17) | 0.0404 (15) | 0.0256 (14) | −0.0049 (13) | 0.0100 (12) | −0.0005 (11) |
S1—C1 | 1.785 (3) | C6—H6 | 0.98 (3) |
S1—S2 | 2.0449 (10) | C8—C13 | 1.396 (4) |
S2—C8 | 1.779 (3) | C8—C9 | 1.416 (4) |
S3—C15 | 1.780 (3) | C9—C10 | 1.380 (4) |
S3—S3i | 2.0431 (13) | C9—C14 | 1.479 (4) |
O1—C7 | 1.219 (3) | C10—C11 | 1.389 (5) |
O2—C7 | 1.321 (3) | C10—H10 | 0.97 (3) |
O2—H2A | 0.91 (4) | C11—C12 | 1.377 (4) |
O3—C14 | 1.212 (3) | C11—H11 | 0.93 (3) |
O4—C14 | 1.312 (3) | C12—C13 | 1.371 (4) |
O4—H4A | 0.82 (4) | C12—H12 | 0.97 (3) |
O5—C21 | 1.215 (3) | C13—H13 | 0.90 (3) |
O6—C21 | 1.306 (3) | C15—C20 | 1.395 (4) |
O6—H6A | 0.85 (4) | C15—C16 | 1.405 (3) |
C1—C6 | 1.396 (4) | C16—C17 | 1.389 (4) |
C1—C2 | 1.404 (3) | C16—C21 | 1.475 (4) |
C2—C3 | 1.397 (4) | C17—C18 | 1.382 (4) |
C2—C7 | 1.474 (4) | C17—H17 | 0.90 (3) |
C3—C4 | 1.378 (4) | C18—C19 | 1.370 (4) |
C3—H3 | 0.90 (3) | C18—H18 | 0.93 (3) |
C4—C5 | 1.373 (4) | C19—C20 | 1.379 (4) |
C4—H4 | 0.96 (3) | C19—H19 | 1.01 (3) |
C5—C6 | 1.382 (4) | C20—H20 | 0.90 (3) |
C5—H5 | 0.96 (3) | ||
C1—S1—S2 | 104.85 (9) | C11—C10—H10 | 121.4 (17) |
C8—S2—S1 | 106.31 (9) | C12—C11—C10 | 119.3 (3) |
C15—S3—S3i | 105.72 (9) | C12—C11—H11 | 114.1 (19) |
C7—O2—H2A | 108 (2) | C10—C11—H11 | 126.4 (19) |
C14—O4—H4A | 111 (3) | C13—C12—C11 | 120.8 (3) |
C21—O6—H6A | 107 (2) | C13—C12—H12 | 121.1 (16) |
C6—C1—C2 | 118.7 (3) | C11—C12—H12 | 118.1 (16) |
C6—C1—S1 | 120.9 (2) | C12—C13—C8 | 121.2 (3) |
C2—C1—S1 | 120.4 (2) | C12—C13—H13 | 122.2 (18) |
C3—C2—C1 | 119.4 (3) | C8—C13—H13 | 116.5 (18) |
C3—C2—C7 | 118.9 (3) | O3—C14—O4 | 122.3 (3) |
C1—C2—C7 | 121.7 (2) | O3—C14—C9 | 122.8 (2) |
C4—C3—C2 | 121.3 (3) | O4—C14—C9 | 114.9 (3) |
C4—C3—H3 | 119 (2) | C20—C15—C16 | 118.2 (2) |
C2—C3—H3 | 120 (2) | C20—C15—S3 | 121.5 (2) |
C5—C4—C3 | 118.9 (3) | C16—C15—S3 | 120.3 (2) |
C5—C4—H4 | 122.5 (19) | C17—C16—C15 | 119.5 (2) |
C3—C4—H4 | 118.5 (19) | C17—C16—C21 | 119.1 (2) |
C4—C5—C6 | 121.3 (3) | C15—C16—C21 | 121.4 (2) |
C4—C5—H5 | 120.6 (18) | C18—C17—C16 | 121.3 (3) |
C6—C5—H5 | 118.0 (18) | C18—C17—H17 | 118.5 (19) |
C5—C6—C1 | 120.3 (3) | C16—C17—H17 | 120.1 (19) |
C5—C6—H6 | 120.6 (17) | C19—C18—C17 | 119.2 (3) |
C1—C6—H6 | 119.0 (17) | C19—C18—H18 | 122 (2) |
O1—C7—O2 | 122.4 (3) | C17—C18—H18 | 118 (2) |
O1—C7—C2 | 123.3 (2) | C18—C19—C20 | 120.6 (3) |
O2—C7—C2 | 114.3 (3) | C18—C19—H19 | 119.4 (17) |
C13—C8—C9 | 118.0 (3) | C20—C19—H19 | 120.0 (17) |
C13—C8—S2 | 121.6 (2) | C19—C20—C15 | 121.2 (3) |
C9—C8—S2 | 120.3 (2) | C19—C20—H20 | 122.4 (18) |
C10—C9—C8 | 119.8 (3) | C15—C20—H20 | 116.5 (18) |
C10—C9—C14 | 119.6 (3) | O5—C21—O6 | 122.3 (2) |
C8—C9—C14 | 120.5 (3) | O5—C21—C16 | 123.1 (2) |
C9—C10—C11 | 120.9 (3) | O6—C21—C16 | 114.6 (3) |
C9—C10—H10 | 117.7 (17) |
Symmetry code: (i) −x, y, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C14H10O4S2 |
Mr | 306.34 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 250 |
a, b, c (Å) | 16.4457 (5), 12.8087 (4), 20.9540 (8) |
β (°) | 104.5589 (13) |
V (Å3) | 4272.2 (2) |
Z | 12 |
Radiation type | Mo Kα |
µ (mm−1) | 0.38 |
Crystal size (mm) | 0.18 × 0.18 × 0.12 |
Data collection | |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (SORTAV; Blessing, 1995) |
Tmin, Tmax | 0.886, 0.955 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14048, 4864, 2674 |
Rint | 0.058 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.056, 0.137, 1.02 |
No. of reflections | 4864 |
No. of parameters | 331 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 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.
S1—C1 | 1.785 (3) | O4—C14 | 1.312 (3) |
S1—S2 | 2.0449 (10) | O4—H4A | 0.82 (4) |
S2—C8 | 1.779 (3) | O5—C21 | 1.215 (3) |
S3—C15 | 1.780 (3) | O6—C21 | 1.306 (3) |
S3—S3i | 2.0431 (13) | O6—H6A | 0.85 (4) |
O1—C7 | 1.219 (3) | C2—C7 | 1.474 (4) |
O2—C7 | 1.321 (3) | C9—C14 | 1.479 (4) |
O2—H2A | 0.91 (4) | C16—C21 | 1.475 (4) |
O3—C14 | 1.212 (3) | ||
C1—S1—S2 | 104.85 (9) | C9—C8—S2 | 120.3 (2) |
C8—S2—S1 | 106.31 (9) | C10—C9—C14 | 119.6 (3) |
C15—S3—S3i | 105.72 (9) | C8—C9—C14 | 120.5 (3) |
C7—O2—H2A | 108 (2) | O3—C14—O4 | 122.3 (3) |
C14—O4—H4A | 111 (3) | O3—C14—C9 | 122.8 (2) |
C21—O6—H6A | 107 (2) | O4—C14—C9 | 114.9 (3) |
C6—C1—S1 | 120.9 (2) | C20—C15—S3 | 121.5 (2) |
C2—C1—S1 | 120.4 (2) | C16—C15—S3 | 120.3 (2) |
C3—C2—C7 | 118.9 (3) | C17—C16—C21 | 119.1 (2) |
C1—C2—C7 | 121.7 (2) | C15—C16—C21 | 121.4 (2) |
O1—C7—O2 | 122.4 (3) | O5—C21—O6 | 122.3 (2) |
O1—C7—C2 | 123.3 (2) | O5—C21—C16 | 123.1 (2) |
O2—C7—C2 | 114.3 (3) | O6—C21—C16 | 114.6 (3) |
C13—C8—S2 | 121.6 (2) |
Symmetry code: (i) −x, y, −z+1/2. |
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.