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X-ray powder diffraction, differential scanning calorimetry (DSC)/thermogravimetry (TG) and single-crystal neutron diffraction methods were used to investigate triammonium hydrogen disulfate (NH4)3H(SO4)2 (TAHS) in the temperature range between 293 and 493 K. The temperature-dependent X-ray powder diffraction measurements show a clear hysteresis of the I \leftrightarrow II phase transition of TAHS with transition temperatures of Tup = 412.9 (1) K on heating and of Tdown = 402.6 (1) K on cooling. From the existence of hysteresis and from the jump-like changes of the lattice parameters, the I \leftrightarrow II phase transition of TAHS is considered to be first order. With DSC/TG measurements we confirmed that there is only one phase transition between 293 and 493 K. Through careful investigation on single crystals of TAHS using neutron diffraction, the correct space group (C2/c) of room-temperature TAHS-II phase was confirmed. Crystal structure analysis by single-crystal neutron diffraction showed a strongly elongated displacement ellipsoid of the proton which lies in the middle of the (SO4)H(SO4) dimer with \bar 1 local symmetry. The protons of the NH4 groups also show strongly enlarged anisotropic mean-square displacements. These findings are interpreted in terms of a characteristic proton disorder in the TAHS-II phase.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768108041876/gw5001sup1.cif
Contains datablocks global, nonsplit, split

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108768108041876/gw5001nonsplitsup2.hkl
Contains datablock nonsplit

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108768108041876/gw5001splitsup3.hkl
Contains datablock split

Computing details top

For both compounds, data collection: DIF4N (modified Linux version of DIF4; Stoe & Cie, 1991); cell refinement: DIF4N; data reduction: PRON (Scherf, 1998); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Atoms 5.1; software used to prepare material for publication: ???.

Figures top
[Figure 1]
[Figure 2]
[Figure 3]
[Figure 4]
[Figure 5]
[Figure 6]
[Figure 7]
[Figure 8]
[Figure 9]
[Figure 10]
[Figure 11]
[Figure 12]
(nonsplit) top
Crystal data top
HO8S2·3(H4N)F(000) = 126
Mr = 247.25Dx = 1.825 Mg m3
Dm = 1.825 Mg m3
Dm measured by not measured
Monoclinic, C2/cMelting point: 0 K
Hall symbol: -C 2ycNeutron radiation, λ = 0.87238 Å
a = 15.429 (8) ÅCell parameters from 13 reflections
b = 5.861 (3) Åθ = 17.3–21.6°
c = 10.167 (5) ŵ = 0.22 mm1
β = 101.83 (5)°T = 293 K
V = 899.9 (8) Å3Cuboid, white
Z = 43 × 3 × 3 × 0 (radius) mm
Data collection top
Four circle
diffractometer
θmax = 37.5°, θmin = 3.3°
ω scansh = 1920
1169 measured reflectionsk = 18
1143 independent reflectionsl = 1411
770 reflections with I > 2σ(I)2 standard reflections every 600 min
Rint = 0.039 intensity decay: none
Refinement top
Refinement on F20 restraints
Least-squares matrix: full0 constraints
R[F2 > 2σ(F2)] = 0.094All H-atom parameters refined
wR(F2) = 0.144 w = 1/[σ2(Fo2) + (0.P)2 + 7.P]
where P = (Fo2 + 2Fc2)/3
S = 1.97(Δ/σ)max < 0.001
1143 reflectionsΔρmax = 1.07 e Å3
120 parametersΔρmin = 1.24 e Å3
Crystal data top
HO8S2·3(H4N)V = 899.9 (8) Å3
Mr = 247.25Z = 4
Monoclinic, C2/cNeutron radiation, λ = 0.87238 Å
a = 15.429 (8) ŵ = 0.22 mm1
b = 5.861 (3) ÅT = 293 K
c = 10.167 (5) Å3 × 3 × 3 × 0 (radius) mm
β = 101.83 (5)°
Data collection top
Four circle
diffractometer
Rint = 0.039
1169 measured reflections2 standard reflections every 600 min
1143 independent reflections intensity decay: none
770 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0940 restraints
wR(F2) = 0.144All H-atom parameters refined
S = 1.97Δρmax = 1.07 e Å3
1143 reflectionsΔρmin = 1.24 e Å3
120 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
S0.1150 (3)0.2175 (10)0.4630 (6)0.0237 (10)
N10.50.2298 (5)0.250.0296 (6)
N20.19904 (14)0.2766 (4)0.1531 (2)0.0343 (5)
O10.01474 (18)0.1836 (6)0.4428 (4)0.0386 (8)
O20.1504 (2)0.2223 (7)0.6049 (3)0.0393 (8)
O30.1286 (2)0.4326 (6)0.3982 (4)0.0416 (8)
O40.1489 (2)0.0278 (6)0.3979 (4)0.0427 (9)
H10000.079 (5)
H20.4648 (7)0.131 (2)0.1834 (11)0.105 (4)
H30.4569 (8)0.310 (3)0.2747 (19)0.171 (8)
H40.2601 (6)0.310 (2)0.1698 (14)0.117 (5)
H50.1695 (10)0.387 (3)0.0978 (16)0.142 (6)
H60.1900 (7)0.1303 (17)0.1146 (12)0.100 (4)
H70.1772 (8)0.283 (3)0.2313 (10)0.127 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S0.022 (2)0.025 (2)0.024 (3)0.0034 (19)0.004 (2)0.002 (2)
N10.0288 (11)0.0327 (14)0.0260 (15)00.0025 (12)0
N20.0388 (11)0.0303 (10)0.0332 (12)0.0074 (9)0.0057 (9)0.0008 (10)
O10.0182 (11)0.0463 (19)0.050 (2)0.0017 (12)0.0032 (12)0.0020 (16)
O20.0345 (13)0.057 (2)0.0240 (14)0.0075 (14)0.0008 (13)0.0002 (15)
O30.0415 (16)0.0324 (15)0.049 (2)0.0023 (13)0.0048 (14)0.0176 (15)
O40.0364 (14)0.0354 (16)0.060 (2)0.0002 (13)0.0184 (16)0.0181 (15)
H10.026 (3)0.143 (13)0.064 (7)0.002 (5)0.001 (4)0.059 (8)
H20.087 (6)0.128 (9)0.085 (7)0.002 (6)0.015 (5)0.043 (7)
H30.089 (7)0.188 (15)0.222 (17)0.064 (9)0.002 (9)0.105 (14)
H40.058 (5)0.117 (9)0.172 (11)0.022 (5)0.014 (6)0.079 (9)
H50.135 (10)0.136 (11)0.157 (13)0.055 (9)0.035 (9)0.089 (11)
H60.094 (6)0.067 (5)0.130 (10)0.021 (5)0.001 (6)0.054 (6)
H70.130 (9)0.195 (15)0.069 (6)0.037 (10)0.050 (6)0.008 (8)
Geometric parameters (Å, º) top
S—O21.434 (7)N1—H30.891 (12)
S—O41.446 (6)N2—H40.943 (9)
S—O31.458 (6)N2—H50.918 (13)
S—O11.531 (5)N2—H60.941 (9)
N1—H20.969 (11)N2—H70.925 (10)
O2—S—O4112.1 (4)H4—N2—H5108.3 (14)
O2—S—O3112.1 (4)H4—N2—H6108.9 (9)
O4—S—O3111.0 (4)H5—N2—H6112.1 (13)
O2—S—O1107.7 (4)H4—N2—H7111.3 (11)
O4—S—O1106.9 (4)H5—N2—H7106.0 (15)
O3—S—O1106.7 (4)H6—N2—H7110.2 (14)
H2—N1—H399.7 (10)
(split) top
Crystal data top
HO8S2·3(H4N)F(000) = 126
Mr = 247.25Dx = 1.825 Mg m3
Dm = 1.825 Mg m3
Dm measured by not measured
Monoclinic, C2/cMelting point: 0 K
Hall symbol: -C 2ycNeutron radiation, λ = 0.87238 Å
a = 15.429 (8) ÅCell parameters from 13 reflections
b = 5.861 (3) Åθ = 17.3–21.6°
c = 10.167 (5) ŵ = 0.22 mm1
β = 101.83 (5)°T = 293 K
V = 899.9 (8) Å3Cuboid, white
Z = 43 × 3 × 3 × 0 (radius) mm
Data collection top
Four circle
diffractometer
θmax = 37.5°, θmin = 3.3°
ω scansh = 1920
1169 measured reflectionsk = 18
1143 independent reflectionsl = 1411
770 reflections with I > 2σ(I)2 standard reflections every 600 min
Rint = 0.039 intensity decay: none
Refinement top
Refinement on F20 restraints
Least-squares matrix: full0 constraints
R[F2 > 2σ(F2)] = 0.094All H-atom parameters refined
wR(F2) = 0.144 w = 1/[σ2(Fo2) + (0.P)2 + 7.P]
where P = (Fo2 + 2Fc2)/3
S = 1.98(Δ/σ)max < 0.001
1143 reflectionsΔρmax = 1.11 e Å3
118 parametersΔρmin = 1.24 e Å3
Crystal data top
HO8S2·3(H4N)V = 899.9 (8) Å3
Mr = 247.25Z = 4
Monoclinic, C2/cNeutron radiation, λ = 0.87238 Å
a = 15.429 (8) ŵ = 0.22 mm1
b = 5.861 (3) ÅT = 293 K
c = 10.167 (5) Å3 × 3 × 3 × 0 (radius) mm
β = 101.83 (5)°
Data collection top
Four circle
diffractometer
Rint = 0.039
1169 measured reflections2 standard reflections every 600 min
1143 independent reflections intensity decay: none
770 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0940 restraints
wR(F2) = 0.144All H-atom parameters refined
S = 1.98Δρmax = 1.11 e Å3
1143 reflectionsΔρmin = 1.24 e Å3
118 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
S0.1150 (3)0.2176 (10)0.4629 (6)0.0232 (10)
N10.50.2298 (5)0.250.0292 (6)
N20.19905 (14)0.2765 (4)0.1531 (2)0.0339 (5)
O10.01501 (17)0.1849 (6)0.4426 (4)0.0391 (8)
O20.1504 (2)0.2223 (7)0.6049 (3)0.0390 (8)
O30.1286 (2)0.4326 (6)0.3981 (4)0.0412 (8)
O40.1490 (2)0.0278 (6)0.3979 (4)0.0422 (9)
H10.0006 (8)0.0424 (16)0.0134 (12)0.035 (2)*0.5
H20.4648 (7)0.130 (2)0.1834 (11)0.104 (4)
H30.4567 (8)0.309 (3)0.2749 (19)0.171 (8)
H40.2602 (6)0.310 (2)0.1698 (14)0.116 (4)
H50.1694 (10)0.388 (3)0.0978 (16)0.141 (6)
H60.1900 (7)0.1304 (16)0.1145 (12)0.100 (4)
H70.1771 (8)0.283 (3)0.2314 (10)0.126 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S0.021 (2)0.025 (2)0.023 (3)0.0036 (19)0.004 (2)0.001 (2)
N10.0285 (11)0.0322 (14)0.0256 (15)00.0022 (12)0
N20.0384 (11)0.0300 (10)0.0327 (11)0.0074 (9)0.0055 (9)0.0007 (10)
O10.0184 (10)0.0462 (19)0.052 (2)0.0003 (12)0.0044 (12)0.0007 (15)
O20.0342 (13)0.057 (2)0.0237 (14)0.0075 (14)0.0007 (13)0.0001 (15)
O30.0413 (16)0.0319 (15)0.048 (2)0.0022 (13)0.0048 (14)0.0177 (15)
O40.0362 (14)0.0346 (16)0.059 (2)0.0001 (13)0.0184 (16)0.0180 (15)
H20.085 (6)0.127 (9)0.085 (7)0.000 (6)0.015 (5)0.044 (7)
H30.089 (7)0.186 (15)0.224 (17)0.063 (9)0.003 (9)0.104 (14)
H40.057 (4)0.117 (9)0.171 (11)0.022 (5)0.014 (6)0.079 (8)
H50.134 (10)0.135 (11)0.157 (13)0.055 (9)0.034 (9)0.089 (11)
H60.093 (6)0.067 (5)0.130 (10)0.022 (5)0.001 (6)0.054 (6)
H70.130 (9)0.193 (15)0.068 (6)0.035 (10)0.051 (6)0.007 (8)
Geometric parameters (Å, º) top
S—O21.434 (7)N1—H30.893 (12)
S—O41.446 (6)N2—H40.944 (9)
S—O31.457 (6)N2—H50.919 (13)
S—O11.526 (5)N2—H60.940 (9)
N1—H20.972 (11)N2—H70.928 (10)
O2—S—O4112.1 (4)H4—N2—H5108.4 (14)
O2—S—O3112.2 (4)H4—N2—H6108.8 (9)
O4—S—O3111.1 (4)H5—N2—H6112.2 (13)
O2—S—O1107.7 (4)H4—N2—H7111.3 (11)
O4—S—O1107.0 (4)H5—N2—H7105.9 (15)
O3—S—O1106.4 (4)H6—N2—H7110.3 (13)
H2—N1—H399.7 (10)

Experimental details

(nonsplit)(split)
Crystal data
Chemical formulaHO8S2·3(H4N)HO8S2·3(H4N)
Mr247.25247.25
Crystal system, space groupMonoclinic, C2/cMonoclinic, C2/c
Temperature (K)293293
a, b, c (Å)15.429 (8), 5.861 (3), 10.167 (5)15.429 (8), 5.861 (3), 10.167 (5)
β (°) 101.83 (5) 101.83 (5)
V3)899.9 (8)899.9 (8)
Z44
Radiation typeNeutron, λ = 0.87238 ÅNeutron, λ = 0.87238 Å
µ (mm1)0.220.22
Crystal size (mm)3 × 3 × 3 × 0 (radius)3 × 3 × 3 × 0 (radius)
Data collection
DiffractometerFour circle
diffractometer
Four circle
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
1169, 1143, 770 1169, 1143, 770
Rint0.0390.039
(sin θ/λ)max1)0.6970.697
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.094, 0.144, 1.97 0.094, 0.144, 1.98
No. of reflections11431143
No. of parameters120118
H-atom treatmentAll H-atom parameters refinedAll H-atom parameters refined
Δρmax, Δρmin (e Å3)1.07, 1.241.11, 1.24

Computer programs: DIF4N (modified Linux version of DIF4; Stoe & Cie, 1991), DIF4N, PRON (Scherf, 1998), SHELXL97 (Sheldrick, 1997), Atoms 5.1, ???.

 

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