S-[4-(Tri­methyl­ammonio)­phenyl]thio­sulfate, an aromatic organic thio­sulfate

The title compound, C₉H₁₃NO₃S₂, exists as a zwitterion with crystallographic mirror symmetry. The central S atom of the S₂O₃ group adopts a slightly distorted tetrahedral coordination geometry. The S—S bond length is 2.1137 (7) Å, while the S—O bond lengths are in the range 1.4417 (12)–1.457 (2) Å. The zwitterions in the crystal adopt a head-to-tail arrangement, which leads to the formation of a three-dimensional network through C—H...O hydrogen bonds.

S1. Comment

Zwitterionic organic compounds having a negatively-charged thiolate end readily coordinate to metal ions to form metal thiolates (Ahmed et al., 1998). One such reactant, trimethylammoniophenyl-4-thiol hexafluorophosphate, reacts with metal ions to form cluster complexes (Chen et al., 2004). The ready synthesis of such cluster complexes prompted a similar attempt at preparing a silver cluster complex, but the reaction with silver bromide in the presence of 4,4'-bipyridyldisulfide furnished instead the title compound, (I) (Fig. 1), which is yet another zwitterionic compound. The structure of (I) is a rare example of an organic thiosulfulate, these being limited to one aromatic (Boese et al., 1999) and six aliphatic (Cruz et al., 1995; Foust & Janickis, 1980; Keefe & Stewart, 1972; Okaya, 1996; Steudel et al., 1993; Zhang et al., 1985) examples. In all of these, an ammonium (⁺NH₃ or ⁺NH₂) group interacts with the thiosulfate group through hydrogen bonds, and the sulfur–oxygen distances in the thiosulfate unit are similar to one another, in agreement with the delocalized nature of this group; for example, in CH₃NH₂CH(CH₃)CH(C₆H₅)S₂O₃, the three distances are essentially identical [1.445 (2), 1.448 (2) and 1.456 (2) Å; Cruz et al., 1995]. The simple thiosulfate ion has been isolated in ammonium salts, for example, bis(adamantanium) thiosulfate (Jiang et al., 1998) and bis(tetraethylammonium) thiosulfate dihydrate (Leyten et al., 1988).

The most closely comparible compound is zwitterionic trimethylammoniophenyl-4-sulfonate, which is obtained from the thermally induced rearrangement of methyl dimethylaminophenyl-4-sulfonate (Kusto et al., 1999). The rearrangement has been investigated theoretically (Oda & Sato, 1998), and the driving force has been attributed to the large electric dipolar interactions among the zwitterions in the resulting product (Oda & Sato, 1997). The compound exhibits three phases, viz. Pcn2 at low temperature, Pca2₁ at room temperature and P4₂/ncm at high temperature (Boese et al., 1999). For the low-temperature phase, the sulfur–oxygen distances in the two independent molecules [1.448 (3)–1.458 (3) Å; Boese et al., 1999] suggest delocalization of the negative charge over the SO₃ unit.

Compound (I), which crystallizes with imposed mirror symmetry, may be viewed as an arylated thiosulfate product. Atom S1 in the S₂O₃ group has a slightly distorted tetrahedral coordination geometry; the mean O—S—O angle (113.98 °) is consistent with those reported for the thiosulfate complexes [Co(en)₂Cl₂](HOCH₂)S₂O₃ (112.8 °; Foust & Janickis, 1980) and Me₂HN(CH₂S₂O₃)₂Na (113.6 °; Zhang et al., 1985), and slightly greater than those in the (Me₄N)₂[Co(H₂O)₄(S₂O₃)₂] complex (110.8 °; Alan et al., 1999). The S1—S2 distance [2.1137 (7) Å] is appreciably longer than those of coordinated thiosulfate ions that exhibit monodentate bonding through the S atoms only, such as (Me₄N)₂[Co(H₂O)₄(S₂O₃)₂] [2.011 (2) Å] and trans- (Me₄N)₂[Ni(H₂O)₄(S₂O₃)₂] [2.014 (1) Å; Alan et al., 1999], but slightly shorter than the S—S bond distance (2.155 Å) of HSSO₃⁻ (Karol & Ralf, 1992) and similar to the values for free alkyl thiosulfate ions, such as Me₂HN(CH₂S₂O₃)₂Na [2.082 (1) Å; Zhang et al., 1985] and [Co(en)₂Cl₂](HOCH₂)S₂O₃ [2.0779 (15) Å; Foust & Janickis, 1980]. The S—O distances in the S₂O₃ group range from 1.4417 (12) to 1.457 (2) Å, which indicates some S—O multiple-bond character [cf. Me₂HN(CH₂S₂O₃)₂Na (1.433–1.455 Å; Zhang et al., 1985)], with the bonding is delocalized between atom S1 and the three O atoms. The mean S—O distance (1.446 Å) is comparable to those found in [Co(en)₂Cl₂](HOCH₂)S₂O₃ (1.449 Å) and Me₂HN(CH₂S₂O₃)₂Na (1.444 Å). The S2—C1 bond distance [1.776 (2) Å] is slightly shorter than those reported in other thiosulfate complexes, such as [Co(en)₂Cl₂](HOCH₂)S₂O₃ [1.829 (4) Å] and Me₂HN(CH₂S₂O₃)₂Na [1.814 (3) Å and 1.816 Å]. Ammonium atom N1 is sp³-hybridized, forming a cationic charge center, and all N—C bond lengths and C—N—C angles are normal.

The zwitterions in the crystal stack in a head-to-tail manner, parallel to the polar c axis, via hydrogen bonds from the methyl H atoms to the O atoms of the S₂O₃ group (Table 2), thereby forming a three-dimensional network.

The dipole moment lies approximately along the vector from the N atom to the single-bonded O atom (dipole moment = 26.78 D) but is not parallel to the c axis. In contrast, the dipole moment of the α phase of trimethylammoniophenyl-4-sulfonate is aligned along a crytallographic axis (calculated dipole moment = 24.97 D; Sarma & Dunitz, 1990).

S2. Experimental

Trimethylammoniumphenyl-4-thiol hexafluorophosphate was synthesized according to the literature procedure (DePamphilis et al., 1974). The resulting compound (0.125 g, 0.4 mmol) in methanol (5 ml) was neutralized with excess triethylamine (0.25 ml); the solution was then reacted with silver bromide powder (0.038 g, 0.2 mmol). The clear colorless solution that resulted after the mixture had been stirred briefly was treated with 4,4'-dipyridyldisulfide (0.044 g, 0.2 mmol) in acetonitrile (2 ml). Prismatic colorless crystals separated from the orange solution after several days, in about 20% yield. The crystals were washed with ether. Analysis found: C 43.52, H 5.18, N 5.32%. Calculated for C₉H₁₃NO₃S₂: C 43.70, H 5.28, N 5.66%. IR (KBr, cm⁻¹): 1488 (s), 1217 (s), 1190 (s), 1024 (s), 1009 (s), 609 (s), 525 (m). Although the compound is not the intended product, the reaction is reproducible. The dipole moments of trimethylammoniophenyl-4-sulfonate and trimethylammoniophenyl-4-thiosulfate were computed at PM3 level by using HYPERCHEM (Hypercube, 2001).

S3. Refinement

H atoms were located from a difference Fourier map and their positions were refined freely [C—H6 = 0.90 (2)–0.97 (4) Å], along with isotropic displacement parameters.

Computing details

Data collection: CrystalClear (Rigaku/MSC, 2001); cell refinement: CrystalClear; data reduction: CrystalStructure (Rigaku/MSC, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. An ORTEPII (Johnson, 1976) plot of C9H13NO3S2, with displacement ellipsoids at the 50% probability level. H atoms are drawn as spheres of arbitrary radii.

4-(Trimethylammonio)phenyl-4-thiosulfate

Crystal data

C9H13NO3S2	F(000) = 260
Mr = 247.32	Dx = 1.531 Mg m^−3
Orthorhombic, Pmn21	Mo Kα radiation, λ = 0.71070 Å
Hall symbol: p 2ac -2	Cell parameters from 2404 reflections
a = 9.0937 (11) Å	θ = 3.6–27.5°
b = 5.6809 (6) Å	µ = 0.48 mm^−1
c = 10.3830 (11) Å	T = 193 K
V = 536.39 (10) Å^3	Prism, colorless
Z = 2	0.30 × 0.30 × 0.25 mm

Data collection

Rigaku Mercury diffractometer	1291 independent reflections
Radiation source: fine-focus sealed tube	1263 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
Detector resolution: 7.31 pixels mm^-1	θmax = 27.5°, θmin = 3.6°
ω scans	h = −11→10
Absorption correction: multi-scan (Jacobson, 1998)	k = −7→7
Tmin = 0.869, Tmax = 0.889	l = −13→13
5598 measured reflections

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)] = 0.023	All H-atom parameters refined
wR(F^2) = 0.060	w = 1/[σ^2(Fo^2) + (0.0351P)^2 + 0.1062P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max < 0.001
1291 reflections	Δρmax = 0.20 e Å^−3
107 parameters	Δρmin = −0.26 e Å^−3
8 restraints	Absolute structure: Flack (1983), 604 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.02 (8)

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
S1	0.5000	0.38765 (11)	0.49997 (4)	0.02167 (15)
S2	0.5000	0.63423 (9)	0.34752 (5)	0.02380 (15)
O1	0.36708 (14)	0.2514 (2)	0.48708 (14)	0.0361 (3)
O2	0.5000	0.5471 (4)	0.60992 (18)	0.0304 (4)
N1	0.5000	0.0100 (3)	−0.12406 (17)	0.0180 (4)
C1	0.5000	0.4377 (4)	0.2145 (2)	0.0192 (5)
C2	0.63165 (18)	0.3659 (3)	0.15927 (17)	0.0227 (4)
C3	0.63226 (17)	0.2256 (3)	0.05058 (17)	0.0236 (3)
C4	0.5000	0.1583 (3)	−0.0050 (2)	0.0179 (4)
C5	0.5000	−0.2466 (4)	−0.0864 (3)	0.0307 (6)
C6	0.6330 (2)	0.0554 (3)	−0.20634 (16)	0.0272 (4)
H2	0.721 (3)	0.422 (4)	0.192 (2)	0.042 (6)*
H3	0.720 (3)	0.183 (4)	0.014 (2)	0.034 (5)*
H5A	0.582 (3)	−0.272 (4)	−0.035 (2)	0.043 (6)*
H6A	0.714 (2)	0.002 (3)	−0.164 (2)	0.035 (5)*
H5B	0.5000	−0.334 (5)	−0.167 (4)	0.045 (9)*
H6B	0.639 (2)	0.220 (4)	−0.228 (2)	0.037 (6)*
H6C	0.622 (2)	−0.021 (3)	−0.281 (2)	0.028 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0214 (3)	0.0295 (3)	0.0142 (3)	0.000	0.000	−0.0017 (2)
S2	0.0300 (3)	0.0230 (3)	0.0184 (3)	0.000	0.000	−0.0022 (3)
O1	0.0379 (7)	0.0444 (7)	0.0260 (6)	−0.0174 (6)	0.0006 (6)	0.0000 (7)
O2	0.0297 (9)	0.0431 (11)	0.0182 (9)	0.000	0.000	−0.0047 (8)
N1	0.0206 (8)	0.0179 (8)	0.0156 (8)	0.000	0.000	0.0009 (7)
C1	0.0229 (11)	0.0204 (11)	0.0143 (10)	0.000	0.000	0.0018 (9)
C2	0.0178 (8)	0.0292 (9)	0.0212 (8)	0.0013 (6)	−0.0042 (7)	−0.0025 (6)
C3	0.0178 (8)	0.0308 (8)	0.0222 (7)	0.0054 (6)	−0.0006 (6)	−0.0031 (6)
C4	0.0214 (9)	0.0191 (9)	0.0131 (9)	0.000	0.000	0.0034 (10)
C5	0.0472 (17)	0.0195 (12)	0.0255 (13)	0.000	0.000	0.0037 (10)
C6	0.0263 (8)	0.0368 (9)	0.0184 (8)	−0.0016 (8)	0.0063 (6)	−0.0015 (8)

Geometric parameters (Å, º)

S1—O1	1.4417 (12)	C2—C3	1.382 (2)
S1—O1^i	1.4417 (12)	C2—H2	0.93 (3)
S1—O2	1.457 (2)	C3—C4	1.387 (2)
S1—S2	2.1137 (7)	C3—H3	0.91 (2)
S2—C1	1.776 (2)	C4—C3^i	1.387 (2)
N1—C4	1.496 (3)	C5—H5A	0.92 (3)
N1—C6^i	1.5027 (19)	C5—H5B	0.97 (4)
N1—C6	1.5027 (19)	C6—H6A	0.91 (2)
N1—C5	1.509 (3)	C6—H6B	0.97 (2)
C1—C2^i	1.388 (2)	C6—H6C	0.90 (2)
C1—C2	1.388 (2)
O1—S1—O1^i	113.95 (11)	C3—C2—H2	119.4 (14)
O1—S1—O2	113.99 (7)	C1—C2—H2	119.8 (14)
O1^i—S1—O2	113.99 (7)	C2—C3—C4	119.66 (15)
O1—S1—S2	106.64 (6)	C2—C3—H3	119.7 (14)
O1^i—S1—S2	106.64 (6)	C4—C3—H3	120.6 (14)
O2—S1—S2	100.06 (9)	C3—C4—C3^i	120.2 (2)
C1—S2—S1	99.55 (8)	C3—C4—N1	119.90 (11)
C4—N1—C6^i	111.92 (11)	C3^i—C4—N1	119.90 (11)
C4—N1—C6	111.92 (11)	N1—C5—H5A	107.3 (14)
C6^i—N1—C6	107.15 (18)	N1—C5—H5B	106 (2)
C4—N1—C5	109.26 (17)	H5A—C5—H5B	114.6 (16)
C6^i—N1—C5	108.23 (12)	N1—C6—H6A	109.0 (13)
C6—N1—C5	108.23 (12)	N1—C6—H6B	110.4 (14)
C2^i—C1—C2	119.1 (2)	H6A—C6—H6B	112.7 (18)
C2^i—C1—S2	120.37 (11)	N1—C6—H6C	108.7 (13)
C2—C1—S2	120.37 (11)	H6A—C6—H6C	110.4 (18)
C3—C2—C1	120.66 (16)	H6B—C6—H6C	106 (2)
O1—S1—S2—C1	−61.05 (6)	C2—C3—C4—C3^i	−2.0 (3)
O1^i—S1—S2—C1	61.05 (6)	C2—C3—C4—N1	178.87 (16)
O2—S1—S2—C1	180.0	C6^i—N1—C4—C3	−150.58 (17)
S1—S2—C1—C2^i	92.06 (19)	C6—N1—C4—C3	−30.3 (2)
S1—S2—C1—C2	−92.06 (19)	C5—N1—C4—C3	89.57 (16)
C2^i—C1—C2—C3	0.2 (4)	C6^i—N1—C4—C3^i	30.3 (2)
S2—C1—C2—C3	−175.72 (15)	C6—N1—C4—C3^i	150.58 (17)
C1—C2—C3—C4	0.9 (3)	C5—N1—C4—C3^i	−89.57 (16)

Symmetry code: (i) −x+1, y, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5B···O2^ii	0.97 (4)	2.42 (4)	3.363 (3)	165 (3)
C6—H6A···O1^iii	0.91 (2)	2.55 (2)	3.406 (2)	158.0 (16)
C2—H2···O2^iv	0.93 (3)	2.69 (3)	3.4244 (17)	136.5 (17)

Symmetry codes: (ii) x, y−1, z−1; (iii) x+1/2, −y, z−1/2; (iv) x+1/2, −y+1, z−1/2.