Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801008960/ob6047sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801008960/ob6047Isup2.hkl |
CCDC reference: 170759
Crystals of (I) were obtained from an aqueous solution of a 2:1 stoichiometric ratio of L-threonine and sulfuric acid.
The H atoms of the water molecules were located by difference Fourier maps and were refined, while all other H atoms were fixed with geometric restraints using HFIX and allowed to ride on the parent atom.
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1999); software used to prepare material for publication: SHELXL97.
2C4H10NO3+·SO42−·H2O | F(000) = 752 |
Mr = 354.34 | Dx = 1.551 Mg m−3 Dm = 1.54 Mg m−3 Dm measured by floatation in carbon tetrachloride and xylene |
Monoclinic, C2 | Mo Kα radiation, λ = 0.71073 Å |
a = 23.096 (4) Å | Cell parameters from 25 reflections |
b = 6.281 (9) Å | θ = 10.8–14.4° |
c = 11.648 (1) Å | µ = 0.27 mm−1 |
β = 116.122 (9)° | T = 293 K |
V = 1517 (2) Å3 | Needles, colorless |
Z = 4 | 0.5 × 0.45 × 0.33 mm |
Enraf-Nonius sealed tube diffractometer | 1675 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.018 |
Graphite monochromator | θmax = 25.0°, θmin = 2.0° |
ω–2θ scans | h = −1→27 |
Absorption correction: ψ scan (North et al., 1968) | k = −1→7 |
Tmin = 0.869, Tmax = 0.914 | l = −13→12 |
1872 measured reflections | 25 standard reflections every 3 reflections |
1732 independent reflections | intensity decay: none |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.032 | w = 1/[σ2(Fo2) + (0.0764P)2 + 1.0496P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.094 | (Δ/σ)max < 0.001 |
S = 0.98 | Δρmax = 0.26 e Å−3 |
1732 reflections | Δρmin = −0.32 e Å−3 |
213 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.026 (2) |
Primary atom site location: structure-invariant direct methods | Absolute structure: (Flack, 1983) |
Secondary atom site location: difference Fourier map | Absolute structure parameter: −0.07 (10) |
2C4H10NO3+·SO42−·H2O | V = 1517 (2) Å3 |
Mr = 354.34 | Z = 4 |
Monoclinic, C2 | Mo Kα radiation |
a = 23.096 (4) Å | µ = 0.27 mm−1 |
b = 6.281 (9) Å | T = 293 K |
c = 11.648 (1) Å | 0.5 × 0.45 × 0.33 mm |
β = 116.122 (9)° |
Enraf-Nonius sealed tube diffractometer | 1675 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.018 |
Tmin = 0.869, Tmax = 0.914 | 25 standard reflections every 3 reflections |
1872 measured reflections | intensity decay: none |
1732 independent reflections |
R[F2 > 2σ(F2)] = 0.032 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.094 | Δρmax = 0.26 e Å−3 |
S = 0.98 | Δρmin = −0.32 e Å−3 |
1732 reflections | Absolute structure: (Flack, 1983) |
213 parameters | Absolute structure parameter: −0.07 (10) |
1 restraint |
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 | 0.12376 (3) | 0.18012 (12) | 0.15518 (6) | 0.0233 (2) | |
O1 | 0.10142 (10) | 0.0461 (4) | 0.0385 (2) | 0.0393 (6) | |
O2 | 0.07958 (10) | 0.1482 (4) | 0.21372 (19) | 0.0335 (5) | |
O3 | 0.12167 (11) | 0.4041 (4) | 0.1165 (2) | 0.0406 (6) | |
O4 | 0.18916 (10) | 0.1178 (5) | 0.2433 (2) | 0.0394 (6) | |
O1A | 0.23195 (10) | 0.0417 (5) | 0.9916 (2) | 0.0380 (6) | |
O1B | 0.13354 (9) | 0.1455 (4) | 0.85151 (19) | 0.0335 (5) | |
H1B | 0.1222 | 0.0820 | 0.8997 | 0.050* | |
C11 | 0.19592 (13) | 0.1223 (5) | 0.8917 (2) | 0.0251 (6) | |
C12 | 0.21886 (11) | 0.2074 (5) | 0.7972 (2) | 0.0231 (6) | |
H12 | 0.2024 | 0.3527 | 0.7739 | 0.028* | |
N11 | 0.29024 (10) | 0.2174 (4) | 0.8618 (2) | 0.0250 (6) | |
H11A | 0.3046 | 0.2679 | 0.8077 | 0.038* | |
H11B | 0.3061 | 0.0874 | 0.8870 | 0.038* | |
H11C | 0.3029 | 0.3027 | 0.9295 | 0.038* | |
C13 | 0.19350 (13) | 0.0731 (6) | 0.6746 (3) | 0.0282 (7) | |
H13 | 0.1471 | 0.0999 | 0.6276 | 0.034* | |
C14 | 0.22416 (16) | 0.1343 (7) | 0.5879 (3) | 0.0428 (9) | |
H14A | 0.2072 | 0.0455 | 0.5132 | 0.064* | |
H14B | 0.2700 | 0.1153 | 0.6328 | 0.064* | |
H14C | 0.2147 | 0.2806 | 0.5629 | 0.064* | |
O1C | 0.20185 (9) | −0.1482 (4) | 0.7063 (2) | 0.0339 (5) | |
H1C | 0.2380 | −0.1857 | 0.7178 | 0.051* | |
O2A | 0.12088 (9) | 0.6655 (5) | 0.87761 (17) | 0.0368 (6) | |
O2B | 0.09874 (9) | 0.6397 (5) | 0.67159 (17) | 0.0354 (6) | |
H2B | 0.1312 | 0.7129 | 0.6926 | 0.053* | |
C21 | 0.08573 (12) | 0.6159 (5) | 0.7699 (2) | 0.0250 (6) | |
C22 | 0.02032 (13) | 0.5186 (5) | 0.7319 (2) | 0.0237 (6) | |
H22 | 0.0174 | 0.3858 | 0.6855 | 0.028* | |
N21 | 0.01341 (11) | 0.4693 (5) | 0.8498 (2) | 0.0265 (6) | |
H21A | −0.0252 | 0.4121 | 0.8289 | 0.040* | |
H21B | 0.0173 | 0.5885 | 0.8939 | 0.040* | |
H21C | 0.0439 | 0.3776 | 0.8975 | 0.040* | |
C23 | −0.03193 (12) | 0.6721 (6) | 0.6437 (2) | 0.0290 (6) | |
H23 | −0.0309 | 0.6685 | 0.5606 | 0.035* | |
O2C | −0.01522 (11) | 0.8823 (4) | 0.6921 (2) | 0.0398 (6) | |
H2C | −0.0383 | 0.9195 | 0.7255 | 0.060* | |
C24 | −0.09955 (14) | 0.6109 (9) | 0.6208 (3) | 0.0492 (10) | |
H24A | −0.1297 | 0.7127 | 0.5645 | 0.074* | |
H24B | −0.1022 | 0.6090 | 0.7008 | 0.074* | |
H24C | −0.1096 | 0.4721 | 0.5825 | 0.074* | |
OW1 | 0.0000 | 0.7880 (6) | 0.0000 | 0.0318 (7) | |
HW1 | 0.0343 (19) | 0.847 (11) | 0.019 (4) | 0.067 (15)* | |
OW2 | 0.0000 | 0.1407 (8) | 0.5000 | 0.106 (3) | |
HW2 | −0.012 (4) | 0.053 (13) | 0.543 (6) | 0.13 (3)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0237 (3) | 0.0195 (4) | 0.0307 (3) | 0.0005 (3) | 0.0156 (3) | 0.0009 (3) |
O1 | 0.0383 (11) | 0.0466 (17) | 0.0423 (12) | −0.0143 (12) | 0.0262 (10) | −0.0136 (12) |
O2 | 0.0383 (10) | 0.0290 (14) | 0.0444 (10) | 0.0009 (11) | 0.0284 (9) | 0.0024 (11) |
O3 | 0.0420 (12) | 0.0239 (13) | 0.0589 (14) | −0.0011 (10) | 0.0250 (11) | 0.0106 (12) |
O4 | 0.0319 (10) | 0.0403 (15) | 0.0422 (11) | 0.0073 (11) | 0.0128 (9) | 0.0029 (12) |
O1A | 0.0312 (10) | 0.0454 (16) | 0.0347 (11) | −0.0037 (11) | 0.0119 (9) | 0.0138 (11) |
O1B | 0.0271 (9) | 0.0359 (15) | 0.0430 (10) | 0.0045 (10) | 0.0205 (8) | 0.0105 (11) |
C11 | 0.0266 (12) | 0.0192 (15) | 0.0298 (13) | −0.0007 (12) | 0.0126 (11) | 0.0002 (12) |
C12 | 0.0201 (11) | 0.0210 (15) | 0.0272 (12) | 0.0005 (12) | 0.0094 (10) | 0.0027 (13) |
N11 | 0.0223 (10) | 0.0245 (15) | 0.0259 (10) | −0.0039 (10) | 0.0084 (9) | −0.0044 (10) |
C13 | 0.0208 (12) | 0.0336 (18) | 0.0273 (13) | −0.0001 (13) | 0.0081 (10) | 0.0012 (14) |
C14 | 0.0505 (17) | 0.052 (3) | 0.0280 (13) | −0.0107 (19) | 0.0192 (13) | −0.0017 (17) |
O1C | 0.0270 (10) | 0.0276 (13) | 0.0495 (12) | −0.0050 (10) | 0.0189 (10) | −0.0086 (11) |
O2A | 0.0308 (10) | 0.0447 (16) | 0.0258 (9) | −0.0122 (12) | 0.0041 (8) | 0.0016 (12) |
O2B | 0.0318 (10) | 0.0467 (17) | 0.0317 (9) | −0.0134 (11) | 0.0177 (8) | −0.0043 (11) |
C21 | 0.0248 (12) | 0.0206 (14) | 0.0282 (13) | 0.0023 (12) | 0.0104 (10) | 0.0012 (12) |
C22 | 0.0251 (13) | 0.0240 (15) | 0.0231 (12) | −0.0025 (12) | 0.0117 (10) | −0.0042 (12) |
N21 | 0.0279 (12) | 0.0255 (14) | 0.0257 (11) | −0.0008 (11) | 0.0115 (9) | 0.0042 (10) |
C23 | 0.0251 (12) | 0.0384 (18) | 0.0228 (12) | −0.0009 (15) | 0.0101 (10) | 0.0040 (15) |
O2C | 0.0450 (13) | 0.0289 (13) | 0.0573 (14) | 0.0063 (12) | 0.0333 (12) | 0.0070 (12) |
C24 | 0.0230 (13) | 0.070 (3) | 0.0469 (16) | −0.0018 (18) | 0.0087 (12) | 0.019 (2) |
OW1 | 0.0289 (15) | 0.0262 (17) | 0.0417 (17) | 0.000 | 0.0169 (14) | 0.000 |
OW2 | 0.240 (8) | 0.030 (3) | 0.087 (3) | 0.000 | 0.106 (5) | 0.000 |
S1—O4 | 1.457 (2) | O1C—H1C | 0.8200 |
S1—O2 | 1.4692 (19) | O2A—C21 | 1.197 (3) |
S1—O3 | 1.471 (3) | O2B—C21 | 1.314 (3) |
S1—O1 | 1.485 (2) | O2B—H2B | 0.8200 |
O1A—C11 | 1.204 (4) | C21—C22 | 1.504 (4) |
O1B—C11 | 1.312 (3) | C22—N21 | 1.484 (3) |
O1B—H1B | 0.8200 | C22—C23 | 1.533 (4) |
C11—C12 | 1.515 (4) | C22—H22 | 0.9800 |
C12—N11 | 1.482 (3) | N21—H21A | 0.8900 |
C12—C13 | 1.535 (4) | N21—H21B | 0.8900 |
C12—H12 | 0.9800 | N21—H21C | 0.8900 |
N11—H11A | 0.8900 | C23—O2C | 1.420 (5) |
N11—H11B | 0.8900 | C23—C24 | 1.514 (4) |
N11—H11C | 0.8900 | C23—H23 | 0.9800 |
C13—O1C | 1.429 (5) | O2C—H2C | 0.8200 |
C13—C14 | 1.516 (4) | C24—H24A | 0.9600 |
C13—H13 | 0.9800 | C24—H24B | 0.9600 |
C14—H14A | 0.9600 | C24—H24C | 0.9600 |
C14—H14B | 0.9600 | OW1—HW1 | 0.81 (5) |
C14—H14C | 0.9600 | OW2—HW2 | 0.86 (7) |
O4—S1—O2 | 110.68 (13) | H14B—C14—H14C | 109.5 |
O4—S1—O3 | 110.88 (16) | C13—O1C—H1C | 109.5 |
O2—S1—O3 | 109.68 (14) | C21—O2B—H2B | 109.5 |
O4—S1—O1 | 109.09 (15) | O2A—C21—O2B | 125.0 (3) |
O2—S1—O1 | 108.37 (13) | O2A—C21—C22 | 122.9 (2) |
O3—S1—O1 | 108.07 (17) | O2B—C21—C22 | 112.0 (2) |
C11—O1B—H1B | 109.5 | N21—C22—C21 | 108.4 (2) |
O1A—C11—O1B | 125.1 (3) | N21—C22—C23 | 112.2 (2) |
O1A—C11—C12 | 122.5 (2) | C21—C22—C23 | 109.5 (3) |
O1B—C11—C12 | 112.4 (2) | N21—C22—H22 | 108.9 |
N11—C12—C11 | 108.2 (2) | C21—C22—H22 | 108.9 |
N11—C12—C13 | 112.3 (2) | C23—C22—H22 | 108.9 |
C11—C12—C13 | 111.7 (3) | C22—N21—H21A | 109.5 |
N11—C12—H12 | 108.2 | C22—N21—H21B | 109.5 |
C11—C12—H12 | 108.2 | H21A—N21—H21B | 109.5 |
C13—C12—H12 | 108.2 | C22—N21—H21C | 109.5 |
C12—N11—H11A | 109.5 | H21A—N21—H21C | 109.5 |
C12—N11—H11B | 109.5 | H21B—N21—H21C | 109.5 |
H11A—N11—H11B | 109.5 | O2C—C23—C24 | 112.7 (3) |
C12—N11—H11C | 109.5 | O2C—C23—C22 | 108.8 (2) |
H11A—N11—H11C | 109.5 | C24—C23—C22 | 113.9 (3) |
H11B—N11—H11C | 109.5 | O2C—C23—H23 | 107.0 |
O1C—C13—C14 | 111.7 (3) | C24—C23—H23 | 107.0 |
O1C—C13—C12 | 109.9 (2) | C22—C23—H23 | 107.0 |
C14—C13—C12 | 112.4 (3) | C23—O2C—H2C | 109.5 |
O1C—C13—H13 | 107.5 | C23—C24—H24A | 109.5 |
C14—C13—H13 | 107.5 | C23—C24—H24B | 109.5 |
C12—C13—H13 | 107.5 | H24A—C24—H24B | 109.5 |
C13—C14—H14A | 109.5 | C23—C24—H24C | 109.5 |
C13—C14—H14B | 109.5 | H24A—C24—H24C | 109.5 |
H14A—C14—H14B | 109.5 | H24B—C24—H24C | 109.5 |
C13—C14—H14C | 109.5 | HW1—OW1—HW1i | 125.5 (9) |
H14A—C14—H14C | 109.5 | HW2—OW2—HW2ii | 101.0 (10) |
O1A—C11—C12—N11 | −12.6 (4) | O2A—C21—C22—N21 | −8.3 (4) |
O1B—C11—C12—N11 | 167.9 (3) | O2B—C21—C22—N21 | 172.1 (3) |
O1A—C11—C12—C13 | 111.5 (3) | O2A—C21—C22—C23 | 114.4 (3) |
O1B—C11—C12—C13 | −68.0 (3) | O2B—C21—C22—C23 | −65.2 (3) |
N11—C12—C13—O1C | 75.8 (3) | N21—C22—C23—O2C | 78.6 (3) |
C11—C12—C13—O1C | −46.0 (3) | C21—C22—C23—O2C | −41.9 (3) |
N11—C12—C13—C14 | −49.2 (4) | N21—C22—C23—C24 | −48.1 (4) |
C11—C12—C13—C14 | −171.0 (3) | C21—C22—C23—C24 | −168.5 (3) |
Symmetry codes: (i) −x, y, −z; (ii) −x, y, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1B—H1B···O1iii | 0.82 | 1.89 | 2.666 (3) | 157 |
N11—H11A···O4iv | 0.89 | 2.30 | 2.927 (5) | 128 |
N11—H11B···O3v | 0.89 | 2.04 | 2.761 (4) | 137 |
N11—H11C···O1Avi | 0.89 | 2.10 | 2.846 (4) | 141 |
N11—H11C···O2Avii | 0.89 | 2.33 | 2.837 (3) | 117 |
N11—H11C···O1iv | 0.89 | 2.58 | 3.052 (4) | 114 |
O1C—H1C···O4v | 0.82 | 1.97 | 2.746 (3) | 157 |
O2B—H2B···O1Cviii | 0.82 | 1.79 | 2.600 (3) | 167 |
N21—H21A···O2ii | 0.89 | 2.01 | 2.797 (4) | 148 |
N21—H21A···O3ii | 0.89 | 2.57 | 3.337 (3) | 144 |
N21—H21B···OW1iii | 0.89 | 1.92 | 2.764 (4) | 157 |
N21—H21C···O3iii | 0.89 | 2.39 | 3.038 (3) | 130 |
N21—H21C···O1iii | 0.89 | 2.62 | 3.477 (5) | 161 |
O2C—H2C···O2ix | 0.82 | 2.02 | 2.764 (3) | 151 |
OW1—HW1···O1viii | 0.81 (5) | 1.93 (5) | 2.719 (3) | 165 (6) |
OW2—HW2···O2Cx | 0.86 (7) | 2.07 (7) | 2.908 (4) | 162 (7) |
Symmetry codes: (ii) −x, y, −z+1; (iii) x, y, z+1; (iv) −x+1/2, y+1/2, −z+1; (v) −x+1/2, y−1/2, −z+1; (vi) −x+1/2, y+1/2, −z+2; (vii) −x+1/2, y−1/2, −z+2; (viii) x, y+1, z; (ix) −x, y+1, −z+1; (x) x, y−1, z. |
Experimental details
Crystal data | |
Chemical formula | 2C4H10NO3+·SO42−·H2O |
Mr | 354.34 |
Crystal system, space group | Monoclinic, C2 |
Temperature (K) | 293 |
a, b, c (Å) | 23.096 (4), 6.281 (9), 11.648 (1) |
β (°) | 116.122 (9) |
V (Å3) | 1517 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.27 |
Crystal size (mm) | 0.5 × 0.45 × 0.33 |
Data collection | |
Diffractometer | Enraf-Nonius sealed tube diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.869, 0.914 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1872, 1732, 1675 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.032, 0.094, 0.98 |
No. of reflections | 1732 |
No. of parameters | 213 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.26, −0.32 |
Absolute structure | (Flack, 1983) |
Absolute structure parameter | −0.07 (10) |
Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 1999), SHELXL97.
O1A—C11—C12—N11 | −12.6 (4) | O2A—C21—C22—N21 | −8.3 (4) |
N11—C12—C13—O1C | 75.8 (3) | N21—C22—C23—O2C | 78.6 (3) |
N11—C12—C13—C14 | −49.2 (4) | N21—C22—C23—C24 | −48.1 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1B—H1B···O1i | 0.82 | 1.89 | 2.666 (3) | 157.0 |
N11—H11A···O4ii | 0.89 | 2.30 | 2.927 (5) | 127.6 |
N11—H11B···O3iii | 0.89 | 2.04 | 2.761 (4) | 137.0 |
N11—H11C···O1Aiv | 0.89 | 2.10 | 2.846 (4) | 141.3 |
N11—H11C···O2Av | 0.89 | 2.33 | 2.837 (3) | 116.5 |
N11—H11C···O1ii | 0.89 | 2.58 | 3.052 (4) | 114.3 |
O1C—H1C···O4iii | 0.82 | 1.97 | 2.746 (3) | 157.2 |
O2B—H2B···O1Cvi | 0.82 | 1.79 | 2.600 (3) | 167.3 |
N21—H21A···O2vii | 0.89 | 2.01 | 2.797 (4) | 147.6 |
N21—H21A···O3vii | 0.89 | 2.57 | 3.337 (3) | 144.3 |
N21—H21B···OW1i | 0.89 | 1.92 | 2.764 (4) | 157.3 |
N21—H21C···O3i | 0.89 | 2.39 | 3.038 (3) | 129.5 |
N21—H21C···O1i | 0.89 | 2.62 | 3.477 (5) | 161.4 |
O2C—H2C···O2viii | 0.82 | 2.02 | 2.764 (3) | 151.1 |
OW1—HW1···O1vi | 0.81 (5) | 1.93 (5) | 2.719 (3) | 165 (6) |
OW2—HW2···O2Cix | 0.86 (7) | 2.07 (7) | 2.908 (4) | 162 (7) |
Symmetry codes: (i) x, y, z+1; (ii) −x+1/2, y+1/2, −z+1; (iii) −x+1/2, y−1/2, −z+1; (iv) −x+1/2, y+1/2, −z+2; (v) −x+1/2, y−1/2, −z+2; (vi) x, y+1, z; (vii) −x, y, −z+1; (viii) −x, y+1, −z+1; (ix) x, y−1, z. |
Threonine is the isometric form of amino acids containing more than one asymmetric C atom. The crystal structures of DL-threonine (Shoemaker et al., 1950), L-threonine (Shoemaker et al., 1950) and L-allothreonine (Swaminathan & Srinivasan, 1975) have been reported. In the present study, threonine complex with sulfuric acid, (I), has been investigated.
The geometries of the L-threoninium cations A and B are as expected (Fig. 1 and Table 1). In cation A, the O1A—C11—C12—N11 and O1B—C11—C12—N11 torsion angles are -12.6 (4) and 167.9 (3)°, respectively, and the corresponding torsion angles in B are -8.3 (4) and 172.1 (3)°. This tendency towards non-planarity is also found in various amino acids (Lakshiminarayanan et al., 1967). The side-chain conformation is given by the torsion angles about Cα—Cβ, giving the orientation of the γ atom with respect to N (Lakshiminarayanan et al., 1967). These angles are close to 60, 180 and 300°. In the present case, the Cγ atom moves to a gauche II form [-49.2 (4) and -48.1 (4)°] and the Oγ atom to a gauche I form [75.8 (3) and 78.6 (3)°] for both molecules.
The sulfate anion forms hydrogen bonds with threoninium molecules A and B (Fig. 2 and Table 2). Threonium molecule A is engaged in a three-centred zigzag (Z1) head-to-tail sequence with N11—H11C···O1A(-x + 1/2, y + 1/2, -z + 2) and N11—H11C···O2A(-x + 1/2, y - 1/2, -z + 2) hydrogen bonds connecting 21-related amino acids (Vijayan, 1988). The Oγ atom of threoninium molecule A, as acceptor, links the carboxyl O atom of threoninium molecule B through a strong hydrogen bond, O2B—H2B···O1C(x, y + 1, z). The two water molecules, lying on the twofold axes, link (i) the sulfate groups and (ii) threoninium molecule B through the O2C atom. One of the water molecules, as acceptor, links the amino group of threoninum molecule B, N21—H21B···OW1(x, y, 1 + z). Two bifurcated hydrogen bonds are observed for the N21 amino group with sulfate O atoms through H21A and H21C. A four-centre hydrogen bond is observed in the case of N11—H11C involving the sulfate O atom and the double-bonded O atom of the carboxyl group of both molecules, connecting all the moieties in the structure (Jeffrey & Saengar, 1991). The sulfate anion links through the N11 atom of three threoninium A molecules, resulting in infinite chains along the b axis. The O3 atom of the sulfate anion links the N21 atoms of two threoninium B molecules, resulting in infinite chains along the c axis.