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The title salt, (C2H8NO3S)[SbF6], which contains the proton­ated form of taurine (2-amino­ethane­sulfonic acid), was synthesized in anhydrous hydro­fluoric acid and recrystallized as colourless block-shaped crystals from liquid SO2. In the solid state, a three-dimensional network is observed. This is formed by intra- and inter­molecular N-H...O, N-H...F and O-H...F hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270111047548/ov3009sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270111047548/ov3009Isup2.hkl
Contains datablock I

CCDC reference: 862226

Comment top

Taurine was first isolated from the bile of oxen by the chemists Tiedemann & Gmelin (1827). The crystal structure, with incorrect refinement of the H atoms of taurine, was first described by Sutherland & Young (1963). Three years later, Okaya (1966) showed that taurine is present as a zwitterion. Taurine plays an important role in human metabolism (Tao & Harris, 2004), but until now pure protonated taurine has not been observed in the condensed phase. We present here the first crystal structure of protonated taurine as the hexafluoridoantimonate (SbF6-) salt, namely 2-sulfoethylammonium hexafluoridoantimonate, (I). The salt crystallizes in the orthorhombic space group Pbca with eight molecules in the unit cell. Selected parameters of (I) and the molecular conformation are shown in Fig. 1.

The Sb—F bond lengths in the SbF6- anion are in the range 1.863 (2)–1.898 (2) Å. The Sb—F bond lengths which are involved in hydrogen bonding (Sb1—F2, Sb1—F3, Sb1—F4 and Sb1—F5) are slightly longer than Sb1—F1 and Sb1—F6. These values are in the typical range for an SbF6- anion, as observed by Minkwitz et al. (1992) for [(C6F5)2SF]+.SbF6-. The SbF6- anion forms a slightly distorted octahedron. The S1—O1 and S1—O2 bond lengths [1.437 (2) and 1.428 (2) Å, respectively] are in the typical range between an S—O single and double bond, and are comparable with those in neutral taurine. The S1—O3 bond length (1.548 Å) is about 0.11 Å longer and, therefore, closer in length to an S—O single bond. The other bond lengths are comparable with the neutral compound and show expected values. The S atom is coordinated in a distorted tetrahedral manner (104.9–119.8°). Comparable with the neutral compound, the NH3 group shows a gauche configuration [S1—C1—C2—N1 = -73.9 (3)°] with respect to the SO3H group.

In the crystal structure of (I), the ions are held together by a three-dimensional network of moderate N—H···O, N—H···F and O—H···F hydrogen bonds (Fig. 2). The bond lengths and angles of the hydrogen bonds are listed in Table 1. In the cation, one intramolecular N1—H1A···O1 hydrogen bond [2.906 (3) Å] can be observed, with graph set S6 (Bernstein et al., 1995). This bond is also present in the neutral compound. The cations form chains involving the N1—H1B···O2i hydrogen bond (graph set C6) along the b axis [symmetry code: (i) -x + 3/2, y - 1/2, z], with parallel chains of SbF6- octahedra. Along the a axis, the cations forms zigzag chains through the N1—H1C···O1iii hydrogen bond [2.868 (3) Å; graph set C21(4); symmetry code: (iii) x + 1/2, y, -z + 3/2]. The SbF6- octahedra are also connected to the cations by hydrogen bonds involving atoms F2, F3, F4 and F5. The acceptors F3 and F4 of one SbF6- octahedron are both linked to the donor atom N1 [graph set R12(6)] and build a six-membered ring. The strengths of these two hydrogen bonds [D···A = 2.917 (3) and 3.060 (3) Å, respectively] are only moderate. The N1—H1C···F2 hydrogen bond [3.006 (3) Å] is in the same range. The strongest hydrogen bond is, as expected, O3—H3···F5ii [2.623 (3) Å; symmetry code: (ii) x, -y + 1/2, z - 1/2]. In comparison, in [H3SO4]+.SbF6- (Minkwitz et al., 2002) the O···F contacts are about 0.04–0.09 Å shorter [D···A = 2.58 (1) and 2.53 (1) Å, respectively].

Related literature top

For related literature, see: Bernstein et al. (1995); Minkwitz et al. (1992, 2002); Okaya (1966); Sutherland & Young (1963); Tao & Harris (2004); Tiedemann & Gmelin (1827).

Experimental top

Caution! Avoid contact with the title compound and SbF5. Note that hydrolysis of [SbF6]- salts might form HF, which burns the skin and causes irreparable damage. Safety precautions, such as special gloves and face visor, should be taken when handling these materials. Equipment and instrumentation: all synthetic work and sample handling were performed by employing standard Schlenk techniques. Superacid reactions were carried out in FEP/PFA ampoules, which were closed with stainless steel valves and connected to a stainless steel vacuum line. All reaction vessels and the stainless steel line were dried with fluorine prior to use.

To 2-aminoethanesulfonic acid (1 mmol) in an FEP reactor, an excess of hydrogen fluoride (100 mmol) was distilled at 77 K, followed by SbF5 (1 mmol). The mixture was warmed to 218 K for 5 min. Excess hydrogen fluoride was removed in a dynamic vacuum at 195 K. A colourless powder was obtained, which was then recrystallized from liquid SO2. Colourless crystals of (I) were obtained, which were suitable for X-ray diffraction studies. The crystals are stable under inert gas up to 258 K.

Refinement top

All H atoms were located in a difference Fourier map, included in their observed positions and refined freely.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008), with atomic masses from Coplen (1996); molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: PLATON (Spek, 2009), publCIF (Westrip, 2010) and WinGX (Farrugia, 1999), and with atomic masses from Coplen (1996).

Figures top
[Figure 1] Fig. 1. The independent unit of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines.
[Figure 2] Fig. 2. A view of the unit cell of (I) along the a axis, showing the three-dimensional network of the packing. Hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) -x + 3/2, -y + 1/2, z; (ii) x, -y + 1/2, z - 1/2; (iii) x - 1/2, y, -z + 3/2.]
2-Sulfoethylammonium hexafluoridoantimonate top
Crystal data top
(C2H8NO3S)[SbF6]F(000) = 1376
Mr = 361.90Dx = 2.511 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 5615 reflections
a = 9.9037 (4) Åθ = 4.2–33.7°
b = 11.5575 (4) ŵ = 3.18 mm1
c = 16.7270 (6) ÅT = 100 K
V = 1914.61 (12) Å3Block, colourless
Z = 80.20 × 0.18 × 0.12 mm
Data collection top
Agilent Xcalibur Sapphire3
diffractometer
1870 independent reflections
Radiation source: Enhance (Mo) X-ray Source1543 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.031
Detector resolution: 15.9809 pixels mm-1θmax = 26.0°, θmin = 4.3°
ω scansh = 126
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
k = 1314
Tmin = 0.569, Tmax = 0.702l = 2020
9108 measured reflections
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)] = 0.018Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.043All H-atom parameters refined
S = 0.91 w = 1/[σ2(Fo2) + (0.0266P)2]
where P = (Fo2 + 2Fc2)/3
1870 reflections(Δ/σ)max = 0.002
159 parametersΔρmax = 0.59 e Å3
0 restraintsΔρmin = 0.64 e Å3
Crystal data top
(C2H8NO3S)[SbF6]V = 1914.61 (12) Å3
Mr = 361.90Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 9.9037 (4) ŵ = 3.18 mm1
b = 11.5575 (4) ÅT = 100 K
c = 16.7270 (6) Å0.20 × 0.18 × 0.12 mm
Data collection top
Agilent Xcalibur Sapphire3
diffractometer
1870 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
1543 reflections with I > 2σ(I)
Tmin = 0.569, Tmax = 0.702Rint = 0.031
9108 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0180 restraints
wR(F2) = 0.043All H-atom parameters refined
S = 0.91Δρmax = 0.59 e Å3
1870 reflectionsΔρmin = 0.64 e Å3
159 parameters
Special details top

Experimental. One single crystal was mounted on the goniometer head under an inert gas atmosphere at 243 K and immediately transferred into the cold nitrogen stream (100 K) of the diffractometer for data collection.

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
Sb10.738710 (16)0.211038 (14)0.890475 (10)0.01152 (7)
S10.66503 (7)0.07777 (6)0.63304 (4)0.01191 (14)
O10.62553 (17)0.00189 (16)0.69471 (10)0.0155 (4)
F10.86811 (16)0.23312 (14)0.96989 (10)0.0230 (4)
F60.64011 (16)0.11029 (14)0.95588 (9)0.0234 (4)
F30.83024 (16)0.31295 (13)0.82081 (9)0.0216 (4)
O20.6184 (2)0.19458 (15)0.63557 (11)0.0176 (4)
F40.60242 (16)0.19896 (13)0.81237 (9)0.0186 (3)
O30.6220 (2)0.01896 (17)0.55387 (13)0.0190 (5)
F50.64234 (17)0.33978 (14)0.93175 (9)0.0260 (4)
F20.83041 (17)0.08578 (14)0.84477 (10)0.0242 (4)
N10.8981 (3)0.0889 (2)0.71783 (14)0.0137 (5)
C10.8432 (3)0.0800 (2)0.63107 (17)0.0145 (6)
C20.9073 (3)0.0385 (3)0.63564 (18)0.0179 (6)
H100.869 (3)0.129 (2)0.6735 (16)0.017 (7)*
H110.870 (3)0.114 (2)0.5839 (17)0.013 (7)*
H1B0.918 (3)0.166 (3)0.7145 (17)0.026 (8)*
H21.003 (3)0.036 (2)0.6214 (16)0.017 (8)*
H30.624 (3)0.061 (2)0.5227 (18)0.015 (9)*
H1C0.956 (4)0.055 (3)0.7513 (18)0.028 (9)*
H2A0.864 (4)0.092 (3)0.6026 (19)0.037 (10)*
H1A0.822 (4)0.087 (3)0.7355 (19)0.036 (10)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Sb10.01232 (11)0.01233 (10)0.00992 (10)0.00076 (7)0.00009 (7)0.00046 (6)
S10.0106 (3)0.0126 (3)0.0125 (3)0.0001 (3)0.0003 (3)0.0004 (3)
O10.0134 (9)0.0178 (9)0.0152 (10)0.0008 (8)0.0004 (8)0.0054 (8)
F10.0208 (9)0.0300 (10)0.0183 (9)0.0036 (7)0.0086 (7)0.0013 (7)
F60.0227 (9)0.0315 (10)0.0160 (8)0.0075 (7)0.0004 (7)0.0083 (7)
F30.0167 (9)0.0258 (9)0.0223 (9)0.0076 (7)0.0003 (7)0.0079 (7)
O20.0219 (11)0.0143 (10)0.0166 (10)0.0009 (8)0.0005 (8)0.0003 (8)
F40.0144 (8)0.0269 (9)0.0144 (8)0.0047 (7)0.0039 (7)0.0025 (7)
O30.0273 (12)0.0165 (11)0.0133 (11)0.0023 (9)0.0056 (9)0.0013 (9)
F50.0287 (10)0.0244 (9)0.0250 (9)0.0080 (8)0.0023 (8)0.0095 (7)
F20.0209 (9)0.0206 (9)0.0312 (10)0.0045 (7)0.0011 (8)0.0093 (7)
N10.0123 (13)0.0136 (13)0.0153 (12)0.0006 (11)0.0016 (11)0.0003 (10)
C10.0137 (14)0.0147 (13)0.0150 (15)0.0015 (11)0.0005 (12)0.0024 (12)
C20.0176 (15)0.0187 (15)0.0173 (15)0.0046 (12)0.0026 (13)0.0045 (11)
Geometric parameters (Å, º) top
Sb1—F11.8633 (16)O3—H30.71 (3)
Sb1—F21.8722 (15)N1—C21.496 (4)
Sb1—F61.8725 (15)N1—H1B0.91 (3)
Sb1—F41.8836 (15)N1—H1C0.89 (3)
Sb1—F31.8887 (15)N1—H1A0.81 (4)
Sb1—F51.8977 (15)C1—C21.512 (4)
S1—O21.4275 (19)C1—H100.95 (3)
S1—O11.4370 (18)C1—H110.92 (3)
S1—O31.548 (2)C2—H20.98 (3)
S1—C11.765 (3)C2—H2A0.93 (3)
F1—Sb1—F293.63 (7)O3—S1—C1105.41 (13)
F1—Sb1—F691.56 (7)S1—O3—H3109 (3)
F2—Sb1—F690.61 (7)C2—N1—H1B108.0 (19)
F1—Sb1—F4175.88 (7)C2—N1—H1C111 (2)
F2—Sb1—F490.41 (7)H1B—N1—H1C110 (3)
F6—Sb1—F489.17 (7)C2—N1—H1A112 (2)
F1—Sb1—F391.40 (7)H1B—N1—H1A105 (3)
F2—Sb1—F389.86 (7)H1C—N1—H1A110 (3)
F6—Sb1—F3176.97 (7)C2—C1—S1113.9 (2)
F4—Sb1—F387.83 (7)C2—C1—H10113.4 (17)
F1—Sb1—F588.80 (7)S1—C1—H10105.3 (17)
F2—Sb1—F5177.18 (7)C2—C1—H11107.7 (17)
F6—Sb1—F590.73 (7)S1—C1—H11108.4 (17)
F4—Sb1—F587.14 (7)H10—C1—H11108 (2)
F3—Sb1—F588.68 (7)N1—C2—C1112.0 (2)
O2—S1—O1119.77 (11)N1—C2—H2107.1 (16)
O2—S1—O3110.58 (11)C1—C2—H2111.6 (16)
O1—S1—O3104.94 (12)N1—C2—H2A105 (2)
O2—S1—C1108.07 (13)C1—C2—H2A112 (2)
O1—S1—C1107.16 (12)H2—C2—H2A109 (3)
O2—S1—C1—C2174.9 (2)O3—S1—C1—C266.8 (2)
O1—S1—C1—C244.6 (2)S1—C1—C2—N173.9 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1B···O2i0.91 (3)2.12 (3)2.860 (3)138 (3)
N1—H1B···F4i0.91 (3)2.27 (3)2.917 (3)127 (2)
O3—H3···F5ii0.71 (3)1.92 (3)2.623 (3)173 (3)
N1—H1C···O1iii0.89 (3)2.00 (4)2.868 (3)163 (3)
N1—H1C···F20.89 (3)2.57 (3)3.006 (3)111 (2)
N1—H1A···O10.81 (4)2.29 (4)2.906 (3)134 (3)
N1—H1A···F3i0.81 (4)2.38 (4)3.060 (3)143 (3)
Symmetry codes: (i) x+3/2, y1/2, z; (ii) x, y+1/2, z1/2; (iii) x+1/2, y, z+3/2.

Experimental details

Crystal data
Chemical formula(C2H8NO3S)[SbF6]
Mr361.90
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)100
a, b, c (Å)9.9037 (4), 11.5575 (4), 16.7270 (6)
V3)1914.61 (12)
Z8
Radiation typeMo Kα
µ (mm1)3.18
Crystal size (mm)0.20 × 0.18 × 0.12
Data collection
DiffractometerAgilent Xcalibur Sapphire3
diffractometer
Absorption correctionMulti-scan
(CrysAlis PRO; Agilent, 2011)
Tmin, Tmax0.569, 0.702
No. of measured, independent and
observed [I > 2σ(I)] reflections
9108, 1870, 1543
Rint0.031
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.043, 0.91
No. of reflections1870
No. of parameters159
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.59, 0.64

Computer programs: CrysAlis PRO (Agilent, 2011), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 2008), with atomic masses from Coplen (1996), DIAMOND (Brandenburg, 2009), PLATON (Spek, 2009), publCIF (Westrip, 2010) and WinGX (Farrugia, 1999), and with atomic masses from Coplen (1996).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1B···O2i0.91 (3)2.12 (3)2.860 (3)138 (3)
N1—H1B···F4i0.91 (3)2.27 (3)2.917 (3)127 (2)
O3—H3···F5ii0.71 (3)1.92 (3)2.623 (3)173 (3)
N1—H1C···O1iii0.89 (3)2.00 (4)2.868 (3)163 (3)
N1—H1C···F20.89 (3)2.57 (3)3.006 (3)111 (2)
N1—H1A···O10.81 (4)2.29 (4)2.906 (3)134 (3)
N1—H1A···F3i0.81 (4)2.38 (4)3.060 (3)143 (3)
Symmetry codes: (i) x+3/2, y1/2, z; (ii) x, y+1/2, z1/2; (iii) x+1/2, y, z+3/2.
 

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