The two title compounds of 2,2'-biimidazole (Bim) with 5-sulfosalicylic acid (5-H
2SSA) and 2,2'-bibenzimidazole (Bbim) with 5-H
2SSA are 1:2 organic salts,
viz. C
6H
8N
42+·2C
7H
5O
6S
-, (I), and C
14H
12N
42+·2C
7H
5O
6S
-·3H
2O, (II). The cation of compound (I) lies on a centre of inversion, whereas that of (II) lies on a twofold axis. Whilst compound (I) is anhydrous, three water molecules are incorporated into the crystal structure of (II). The substitution of imidazole H atoms by other chemical groups may favour the incorporation of water molecules into the crystal structure. In both compounds, the component cations and anions adopt a homogeneous arrangement, forming alternating cation and anion layers which run parallel to the (001) plane in (I) and to the (100) plane in (II). By a combination of N-H
O, O-H
O and C-H
O hydrogen bonds, the ions in both compounds are linked into three-dimensional networks. In addition,
-
interactions are observed between symmetry-related benzene rings of Bbim
2+ cations in (II).
Supporting information
CCDC references: 724202; 724203
2,2'-Bisimidazole and 2,2'-bisbenzimidazole were synthesized according to the
methods of Cromer et al. (1987) and Sakamoto et al.
(2000). All
other reagents and solvents were used as obtained. For (I), 1:2 molar
quantities of 2,2'-bisimidazole (0.2 mmol, 26.8 mg) and 5-sulfosaliyclic acid
dihydrate (0.4 mmol, 101.6 mg) were dissolved in 95% methanol (20 ml). The
mixture was stirred for 10 min at ambient temperature and then filtered. The
resulting colourless solution was kept in air for 3 d, yielding colourless
plate crystals. The crystals were filtered off carefully, washed with
distilled water and dried in air (yield: 40%, 46.0 mg, based on the 1:2
organic salt). Similarly, crystals of (II) were obtained by 1:2 molar
quantities of 2,2'-bisbenzimidazole (0.2 mmol, 46.8 mg) and 5-sulfosaliyclic
acid dihydrate (0.4 mmol, 101.6 mg) being dissolved in 95% methanol (20 ml).
The mixture was stirred for 30 min at room temperature and then filtered. The
resulting colourless solution was kept in air for one week, yielding
colourless plate crystals. The crystals were filtered off carefully, washed
with distilled water and dried in air (yield: 55%, 145.0 mg, based on the 1:2
organic salt)
For both compounds, H atoms bonded to aromatic C atoms were positioned
geometrically, with C—H = 0.93 Å, and refined in a riding mode, with
Uiso(H) = 1.2Ueq(aromatic C). H atoms bonded to N and O
atoms were found in difference maps and the N—H and O—H distances were
refined freely [Uiso(H) = 1.2Ueq(N) and 1.5Ueq(O),
respectively].
For both compounds, data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003).
(I) 2,2'-bisimidazolium bis(3-carboxy-4-hydroxybenzenesulfonate)
top
Crystal data top
C6H8N42+·2C7H5O6S− | Z = 1 |
Mr = 570.5 | F(000) = 294 |
Triclinic, P1 | Dx = 1.659 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 5.4296 (5) Å | Cell parameters from 1888 reflections |
b = 8.2995 (7) Å | θ = 2.5–26.0° |
c = 12.7083 (11) Å | µ = 0.31 mm−1 |
α = 85.961 (2)° | T = 297 K |
β = 88.895 (2)° | Plate, colourless |
γ = 89.573 (1)° | 0.20 × 0.16 × 0.04 mm |
V = 571.13 (9) Å3 | |
Data collection top
Bruker SMART APEX CCD area-detector diffractometer | 2451 independent reflections |
Radiation source: fine focus sealed Siemens Mo tube | 1758 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.045 |
0.3° wide ω exposures scans | θmax = 27.0°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | h = −6→6 |
Tmin = 0.931, Tmax = 0.988 | k = −10→10 |
6501 measured reflections | l = −14→16 |
Refinement top
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)] = 0.046 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.146 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0751P)2] where P = (Fo2 + 2Fc2)/3 |
2451 reflections | (Δ/σ)max < 0.001 |
184 parameters | Δρmax = 0.41 e Å−3 |
0 restraints | Δρmin = −0.30 e Å−3 |
Crystal data top
C6H8N42+·2C7H5O6S− | γ = 89.573 (1)° |
Mr = 570.5 | V = 571.13 (9) Å3 |
Triclinic, P1 | Z = 1 |
a = 5.4296 (5) Å | Mo Kα radiation |
b = 8.2995 (7) Å | µ = 0.31 mm−1 |
c = 12.7083 (11) Å | T = 297 K |
α = 85.961 (2)° | 0.20 × 0.16 × 0.04 mm |
β = 88.895 (2)° | |
Data collection top
Bruker SMART APEX CCD area-detector diffractometer | 2451 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | 1758 reflections with I > 2σ(I) |
Tmin = 0.931, Tmax = 0.988 | Rint = 0.045 |
6501 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.046 | 0 restraints |
wR(F2) = 0.146 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.10 | Δρmax = 0.41 e Å−3 |
2451 reflections | Δρmin = −0.30 e Å−3 |
184 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. |
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 | x | y | z | Uiso*/Ueq | |
C1 | 0.4395 (5) | 0.2238 (3) | 1.0122 (2) | 0.0296 (6) | |
C2 | 0.6516 (5) | 0.3191 (3) | 1.0075 (2) | 0.0351 (6) | |
C3 | 0.7613 (5) | 0.3664 (3) | 0.9099 (2) | 0.0402 (7) | |
H3 | 0.9033 | 0.4287 | 0.9069 | 0.048* | |
C4 | 0.6603 (5) | 0.3213 (3) | 0.8189 (2) | 0.0377 (7) | |
H4 | 0.7343 | 0.3530 | 0.7542 | 0.045* | |
C5 | 0.4462 (5) | 0.2276 (3) | 0.8221 (2) | 0.0304 (6) | |
C6 | 0.3387 (5) | 0.1794 (3) | 0.9177 (2) | 0.0302 (6) | |
H6 | 0.1973 | 0.1165 | 0.9199 | 0.036* | |
C7 | 0.3250 (5) | 0.1720 (3) | 1.1134 (2) | 0.0353 (6) | |
C8 | 0.9888 (5) | 0.0813 (3) | 0.4762 (2) | 0.0334 (6) | |
C9 | 0.8511 (7) | 0.3263 (4) | 0.4361 (3) | 0.0558 (9) | |
H9 | 0.7553 | 0.4197 | 0.4359 | 0.067* | |
C10 | 1.0489 (7) | 0.3021 (4) | 0.3758 (3) | 0.0553 (9) | |
H10 | 1.1163 | 0.3761 | 0.3251 | 0.066* | |
N1 | 0.8160 (5) | 0.1875 (3) | 0.4984 (2) | 0.0421 (6) | |
H1 | 0.704 (6) | 0.168 (4) | 0.546 (3) | 0.050* | |
N2 | 1.1354 (5) | 0.1506 (3) | 0.40089 (19) | 0.0422 (6) | |
H2 | 1.244 (6) | 0.106 (4) | 0.366 (3) | 0.051* | |
O1 | 0.1414 (4) | 0.0714 (3) | 1.10746 (17) | 0.0467 (6) | |
H1A | 0.079 (7) | 0.035 (4) | 1.164 (3) | 0.070* | |
O2 | 0.3954 (4) | 0.2168 (3) | 1.19812 (16) | 0.0523 (6) | |
O3 | 0.7570 (4) | 0.3692 (3) | 1.09478 (18) | 0.0500 (6) | |
H3A | 0.670 (8) | 0.338 (5) | 1.146 (3) | 0.075* | |
O4 | 0.0980 (4) | 0.0833 (3) | 0.72930 (15) | 0.0531 (6) | |
O5 | 0.4997 (4) | 0.0814 (3) | 0.64968 (17) | 0.0533 (6) | |
O6 | 0.2659 (5) | 0.3249 (3) | 0.64233 (19) | 0.0688 (8) | |
S1 | 0.31517 (12) | 0.17641 (8) | 0.70293 (5) | 0.0336 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.0322 (14) | 0.0301 (13) | 0.0260 (14) | −0.0020 (10) | 0.0022 (11) | 0.0012 (11) |
C2 | 0.0307 (14) | 0.0334 (14) | 0.0420 (17) | −0.0028 (11) | −0.0022 (12) | −0.0074 (12) |
C3 | 0.0303 (15) | 0.0365 (15) | 0.0538 (19) | −0.0106 (11) | 0.0072 (13) | −0.0048 (13) |
C4 | 0.0343 (15) | 0.0363 (14) | 0.0421 (17) | −0.0074 (11) | 0.0109 (13) | −0.0016 (12) |
C5 | 0.0321 (14) | 0.0302 (13) | 0.0286 (14) | 0.0005 (10) | 0.0026 (11) | −0.0003 (11) |
C6 | 0.0272 (13) | 0.0311 (13) | 0.0319 (15) | −0.0038 (10) | 0.0030 (11) | 0.0016 (11) |
C7 | 0.0357 (15) | 0.0328 (14) | 0.0375 (17) | −0.0040 (11) | 0.0001 (12) | −0.0027 (12) |
C8 | 0.0395 (16) | 0.0313 (13) | 0.0302 (15) | −0.0026 (11) | 0.0025 (12) | −0.0090 (11) |
C9 | 0.080 (2) | 0.0352 (16) | 0.052 (2) | 0.0120 (16) | −0.0034 (19) | 0.0012 (15) |
C10 | 0.086 (3) | 0.0347 (16) | 0.045 (2) | −0.0089 (16) | 0.0065 (18) | 0.0022 (14) |
N1 | 0.0478 (16) | 0.0403 (14) | 0.0384 (15) | 0.0040 (11) | 0.0065 (12) | −0.0070 (11) |
N2 | 0.0533 (16) | 0.0378 (14) | 0.0354 (15) | −0.0063 (11) | 0.0156 (12) | −0.0067 (11) |
O1 | 0.0466 (13) | 0.0548 (13) | 0.0383 (13) | −0.0213 (10) | 0.0086 (10) | −0.0012 (10) |
O2 | 0.0627 (14) | 0.0636 (14) | 0.0310 (12) | −0.0188 (11) | 0.0012 (10) | −0.0035 (10) |
O3 | 0.0462 (13) | 0.0595 (14) | 0.0457 (14) | −0.0175 (10) | −0.0037 (10) | −0.0114 (11) |
O4 | 0.0445 (12) | 0.0816 (16) | 0.0340 (12) | −0.0273 (11) | 0.0061 (10) | −0.0092 (11) |
O5 | 0.0475 (13) | 0.0685 (14) | 0.0452 (13) | 0.0062 (11) | 0.0121 (10) | −0.0180 (11) |
O6 | 0.105 (2) | 0.0461 (13) | 0.0545 (15) | −0.0005 (13) | −0.0266 (14) | 0.0083 (11) |
S1 | 0.0346 (4) | 0.0367 (4) | 0.0290 (4) | −0.0032 (3) | 0.0043 (3) | 0.0004 (3) |
Geometric parameters (Å, º) top
C1—C2 | 1.400 (4) | C8—N2 | 1.334 (4) |
C1—C6 | 1.403 (3) | C8—C8i | 1.445 (5) |
C1—C7 | 1.457 (4) | C9—C10 | 1.330 (5) |
C2—O3 | 1.350 (3) | C9—N1 | 1.363 (4) |
C2—C3 | 1.398 (4) | C9—H9 | 0.9300 |
C3—C4 | 1.366 (4) | C10—N2 | 1.358 (4) |
C3—H3 | 0.9300 | C10—H10 | 0.9300 |
C4—C5 | 1.402 (4) | N1—H1 | 0.86 (3) |
C4—H4 | 0.9300 | N2—H2 | 0.83 (3) |
C5—C6 | 1.373 (4) | O1—H1A | 0.83 (4) |
C5—S1 | 1.765 (3) | O3—H3A | 0.82 (4) |
C6—H6 | 0.9300 | O4—S1 | 1.436 (2) |
C7—O2 | 1.231 (3) | O5—S1 | 1.456 (2) |
C7—O1 | 1.312 (3) | O6—S1 | 1.433 (2) |
C8—N1 | 1.323 (3) | | |
| | | |
C2—C1—C6 | 118.9 (2) | N1—C8—C8i | 126.0 (3) |
C2—C1—C7 | 120.6 (2) | N2—C8—C8i | 126.4 (3) |
C6—C1—C7 | 120.6 (2) | C10—C9—N1 | 106.6 (3) |
O3—C2—C3 | 117.6 (2) | C10—C9—H9 | 126.7 |
O3—C2—C1 | 122.4 (3) | N1—C9—H9 | 126.7 |
C3—C2—C1 | 120.0 (3) | C9—C10—N2 | 108.2 (3) |
C4—C3—C2 | 120.1 (2) | C9—C10—H10 | 125.9 |
C4—C3—H3 | 119.9 | N2—C10—H10 | 125.9 |
C2—C3—H3 | 119.9 | C8—N1—C9 | 109.3 (3) |
C3—C4—C5 | 120.6 (3) | C8—N1—H1 | 123 (2) |
C3—C4—H4 | 119.7 | C9—N1—H1 | 128 (2) |
C5—C4—H4 | 119.7 | C8—N2—C10 | 108.2 (3) |
C6—C5—C4 | 119.6 (3) | C8—N2—H2 | 127 (2) |
C6—C5—S1 | 120.9 (2) | C10—N2—H2 | 124 (2) |
C4—C5—S1 | 119.5 (2) | C7—O1—H1A | 116 (3) |
C5—C6—C1 | 120.8 (2) | C2—O3—H3A | 108 (3) |
C5—C6—H6 | 119.6 | O6—S1—O4 | 113.42 (15) |
C1—C6—H6 | 119.6 | O6—S1—O5 | 110.64 (15) |
O2—C7—O1 | 122.4 (3) | O4—S1—O5 | 111.22 (13) |
O2—C7—C1 | 123.2 (2) | O6—S1—C5 | 106.95 (13) |
O1—C7—C1 | 114.4 (2) | O4—S1—C5 | 107.68 (12) |
N1—C8—N2 | 107.6 (2) | O5—S1—C5 | 106.56 (12) |
| | | |
C6—C1—C2—O3 | 178.8 (2) | C2—C1—C7—O1 | −174.0 (2) |
C7—C1—C2—O3 | −1.0 (4) | C6—C1—C7—O1 | 6.1 (4) |
C6—C1—C2—C3 | −0.9 (4) | N1—C9—C10—N2 | −0.3 (4) |
C7—C1—C2—C3 | 179.3 (2) | N2—C8—N1—C9 | 0.5 (3) |
O3—C2—C3—C4 | −179.0 (2) | C8i—C8—N1—C9 | −178.6 (3) |
C1—C2—C3—C4 | 0.8 (4) | C10—C9—N1—C8 | −0.1 (4) |
C2—C3—C4—C5 | 0.1 (4) | N1—C8—N2—C10 | −0.7 (3) |
C3—C4—C5—C6 | −0.7 (4) | C8i—C8—N2—C10 | 178.4 (3) |
C3—C4—C5—S1 | 178.1 (2) | C9—C10—N2—C8 | 0.6 (4) |
C4—C5—C6—C1 | 0.5 (4) | C6—C5—S1—O6 | 121.9 (2) |
S1—C5—C6—C1 | −178.29 (18) | C4—C5—S1—O6 | −56.9 (2) |
C2—C1—C6—C5 | 0.3 (4) | C6—C5—S1—O4 | −0.3 (3) |
C7—C1—C6—C5 | −179.9 (2) | C4—C5—S1—O4 | −179.1 (2) |
C2—C1—C7—O2 | 5.1 (4) | C6—C5—S1—O5 | −119.7 (2) |
C6—C1—C7—O2 | −174.7 (2) | C4—C5—S1—O5 | 61.5 (2) |
Symmetry code: (i) −x+2, −y, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3A···O2 | 0.82 (4) | 1.89 (4) | 2.624 (3) | 148 (4) |
N1—H1···O5 | 0.86 (3) | 1.82 (4) | 2.661 (3) | 167 (3) |
C9—H9···O6ii | 0.93 | 2.28 | 3.061 (4) | 141 |
C3—H3···O3iii | 0.93 | 2.50 | 3.423 (3) | 171 |
C6—H6···O1iv | 0.93 | 2.47 | 3.382 (3) | 168 |
O1—H1A···O4iv | 0.83 (4) | 1.87 (4) | 2.681 (3) | 166 (4) |
N2—H2···O5i | 0.83 (3) | 2.10 (3) | 2.849 (3) | 151 (3) |
N2—H2···O2v | 0.83 (3) | 2.40 (3) | 2.934 (3) | 123 (3) |
Symmetry codes: (i) −x+2, −y, −z+1; (ii) −x+1, −y+1, −z+1; (iii) −x+2, −y+1, −z+2; (iv) −x, −y, −z+2; (v) x+1, y, z−1. |
(II) 2,2'-bisbenzimidazolium bis(3-carboxy-4-hydroxybenzenesulfonate) trihydrate
top
Crystal data top
C14H12N42+·2C7H5O6S−·3H2O | F(000) = 1504 |
Mr = 724.66 | Dx = 1.556 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 5450 reflections |
a = 25.0519 (9) Å | θ = 2.2–27.5° |
b = 7.3158 (3) Å | µ = 0.26 mm−1 |
c = 17.0309 (6) Å | T = 295 K |
β = 97.553 (3)° | Plate, colourless |
V = 3094.3 (2) Å3 | 0.30 × 0.20 × 0.04 mm |
Z = 4 | |
Data collection top
Bruker SMART APEX CCD area-detector diffractometer | 3008 independent reflections |
Radiation source: fine focus sealed Siemens Mo tube | 2489 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.032 |
0.3° wide ω exposures scans | θmax = 26.0°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | h = −30→30 |
Tmin = 0.918, Tmax = 0.990 | k = −9→8 |
14378 measured reflections | l = −21→20 |
Refinement top
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)] = 0.039 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.118 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0706P)2 + 1.3243P] where P = (Fo2 + 2Fc2)/3 |
3008 reflections | (Δ/σ)max < 0.001 |
243 parameters | Δρmax = 0.29 e Å−3 |
0 restraints | Δρmin = −0.28 e Å−3 |
Crystal data top
C14H12N42+·2C7H5O6S−·3H2O | V = 3094.3 (2) Å3 |
Mr = 724.66 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 25.0519 (9) Å | µ = 0.26 mm−1 |
b = 7.3158 (3) Å | T = 295 K |
c = 17.0309 (6) Å | 0.30 × 0.20 × 0.04 mm |
β = 97.553 (3)° | |
Data collection top
Bruker SMART APEX CCD area-detector diffractometer | 3008 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | 2489 reflections with I > 2σ(I) |
Tmin = 0.918, Tmax = 0.990 | Rint = 0.032 |
14378 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.039 | 0 restraints |
wR(F2) = 0.118 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.29 e Å−3 |
3008 reflections | Δρmin = −0.28 e Å−3 |
243 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. |
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 | x | y | z | Uiso*/Ueq | |
S1 | 0.141309 (18) | 0.45439 (6) | 0.27209 (3) | 0.03440 (17) | |
C1 | 0.22878 (7) | 0.5132 (3) | 0.48699 (11) | 0.0342 (4) | |
C2 | 0.28051 (8) | 0.4665 (3) | 0.47119 (12) | 0.0393 (5) | |
C3 | 0.28885 (8) | 0.4173 (3) | 0.39496 (13) | 0.0503 (6) | |
H3 | 0.3233 | 0.3874 | 0.3846 | 0.060* | |
C4 | 0.24680 (8) | 0.4126 (3) | 0.33488 (12) | 0.0456 (5) | |
H4 | 0.2527 | 0.3793 | 0.2840 | 0.055* | |
C5 | 0.19495 (7) | 0.4577 (3) | 0.35011 (11) | 0.0342 (4) | |
C6 | 0.18605 (7) | 0.5073 (3) | 0.42513 (11) | 0.0335 (4) | |
H6 | 0.1514 | 0.5370 | 0.4349 | 0.040* | |
C7 | 0.21986 (8) | 0.5660 (3) | 0.56797 (11) | 0.0372 (4) | |
C8 | −0.00005 (7) | 0.7961 (3) | 0.29240 (11) | 0.0355 (4) | |
C9 | 0.02778 (7) | 0.8024 (3) | 0.42028 (11) | 0.0338 (4) | |
C10 | −0.02588 (7) | 0.7454 (3) | 0.40907 (11) | 0.0359 (4) | |
C11 | −0.05306 (8) | 0.6999 (3) | 0.47238 (13) | 0.0452 (5) | |
H11 | −0.0887 | 0.6609 | 0.4649 | 0.054* | |
C12 | −0.02463 (9) | 0.7154 (3) | 0.54616 (13) | 0.0500 (5) | |
H12 | −0.0414 | 0.6867 | 0.5902 | 0.060* | |
C13 | 0.02915 (9) | 0.7734 (3) | 0.55736 (13) | 0.0487 (5) | |
H13 | 0.0470 | 0.7816 | 0.6087 | 0.058* | |
C14 | 0.05638 (8) | 0.8183 (3) | 0.49569 (12) | 0.0415 (5) | |
H14 | 0.0920 | 0.8572 | 0.5037 | 0.050* | |
N1 | 0.04191 (6) | 0.8334 (2) | 0.34586 (9) | 0.0357 (4) | |
H1 | 0.0711 (8) | 0.882 (3) | 0.3340 (13) | 0.043* | |
N2 | −0.04156 (7) | 0.7451 (2) | 0.32836 (10) | 0.0388 (4) | |
H2 | −0.0720 (9) | 0.711 (3) | 0.3053 (14) | 0.047* | |
O1 | 0.16956 (6) | 0.6071 (2) | 0.57491 (9) | 0.0506 (4) | |
H1A | 0.1677 (11) | 0.629 (4) | 0.6211 (18) | 0.076* | |
O2 | 0.25576 (6) | 0.5714 (2) | 0.62342 (8) | 0.0515 (4) | |
O3 | 0.32400 (6) | 0.4660 (3) | 0.52733 (10) | 0.0544 (4) | |
H3A | 0.3125 (13) | 0.499 (4) | 0.568 (2) | 0.082* | |
O4 | 0.14455 (5) | 0.6227 (2) | 0.22734 (8) | 0.0457 (4) | |
O5 | 0.15031 (6) | 0.29626 (19) | 0.22315 (8) | 0.0443 (4) | |
O6 | 0.09190 (6) | 0.4432 (2) | 0.30659 (9) | 0.0522 (4) | |
O7 | 0.13160 (6) | 0.9671 (2) | 0.29919 (11) | 0.0520 (4) | |
H7A | 0.1373 (12) | 1.063 (4) | 0.2761 (18) | 0.078* | |
H7B | 0.1523 (12) | 0.887 (4) | 0.2903 (18) | 0.078* | |
O8 | 0.0000 | 0.2042 (4) | 0.2500 | 0.0671 (7) | |
H8A | −0.0289 (12) | 0.265 (5) | 0.236 (2) | 0.101* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
S1 | 0.0363 (3) | 0.0435 (3) | 0.0233 (3) | 0.00036 (19) | 0.00351 (18) | 0.00129 (18) |
C1 | 0.0391 (10) | 0.0369 (10) | 0.0265 (10) | −0.0024 (8) | 0.0042 (8) | 0.0042 (8) |
C2 | 0.0352 (10) | 0.0473 (11) | 0.0348 (11) | −0.0010 (8) | 0.0021 (8) | 0.0042 (8) |
C3 | 0.0362 (11) | 0.0723 (15) | 0.0433 (13) | 0.0106 (10) | 0.0090 (9) | −0.0016 (11) |
C4 | 0.0441 (11) | 0.0629 (14) | 0.0308 (11) | 0.0081 (10) | 0.0087 (9) | −0.0042 (9) |
C5 | 0.0375 (10) | 0.0391 (10) | 0.0259 (10) | 0.0004 (7) | 0.0041 (8) | 0.0035 (7) |
C6 | 0.0341 (9) | 0.0404 (10) | 0.0266 (10) | 0.0014 (7) | 0.0056 (8) | 0.0041 (8) |
C7 | 0.0396 (10) | 0.0445 (11) | 0.0272 (10) | −0.0047 (8) | 0.0030 (8) | 0.0053 (8) |
C8 | 0.0361 (9) | 0.0376 (10) | 0.0326 (10) | 0.0002 (8) | 0.0038 (8) | 0.0001 (8) |
C9 | 0.0344 (9) | 0.0358 (10) | 0.0319 (10) | 0.0011 (7) | 0.0067 (8) | −0.0001 (8) |
C10 | 0.0394 (10) | 0.0366 (10) | 0.0318 (10) | −0.0024 (8) | 0.0058 (8) | −0.0019 (8) |
C11 | 0.0455 (11) | 0.0490 (12) | 0.0429 (12) | −0.0054 (9) | 0.0127 (9) | 0.0006 (10) |
C12 | 0.0598 (13) | 0.0549 (13) | 0.0385 (12) | −0.0020 (10) | 0.0185 (10) | 0.0026 (10) |
C13 | 0.0602 (13) | 0.0551 (13) | 0.0294 (11) | 0.0000 (10) | 0.0007 (9) | −0.0004 (9) |
C14 | 0.0415 (10) | 0.0454 (11) | 0.0361 (11) | −0.0008 (9) | −0.0007 (8) | −0.0004 (9) |
N1 | 0.0325 (8) | 0.0432 (9) | 0.0319 (9) | −0.0032 (7) | 0.0058 (7) | 0.0018 (7) |
N2 | 0.0350 (8) | 0.0469 (10) | 0.0335 (9) | −0.0071 (7) | 0.0013 (7) | −0.0015 (7) |
O1 | 0.0433 (8) | 0.0845 (12) | 0.0244 (7) | 0.0049 (8) | 0.0056 (6) | −0.0032 (8) |
O2 | 0.0459 (8) | 0.0761 (11) | 0.0305 (8) | −0.0030 (7) | −0.0027 (6) | −0.0017 (7) |
O3 | 0.0356 (8) | 0.0847 (12) | 0.0412 (9) | 0.0021 (7) | −0.0019 (7) | 0.0016 (8) |
O4 | 0.0491 (8) | 0.0461 (8) | 0.0399 (8) | 0.0036 (6) | −0.0013 (6) | 0.0094 (7) |
O5 | 0.0584 (8) | 0.0442 (8) | 0.0301 (7) | −0.0011 (6) | 0.0056 (6) | −0.0032 (6) |
O6 | 0.0398 (8) | 0.0841 (12) | 0.0334 (8) | −0.0056 (7) | 0.0076 (6) | −0.0024 (7) |
O7 | 0.0432 (8) | 0.0480 (10) | 0.0665 (11) | −0.0027 (7) | 0.0139 (8) | 0.0055 (8) |
O8 | 0.0720 (17) | 0.0694 (17) | 0.0562 (16) | 0.000 | −0.0050 (13) | 0.000 |
Geometric parameters (Å, º) top
S1—O6 | 1.4406 (15) | C9—N1 | 1.379 (2) |
S1—O4 | 1.4559 (15) | C9—C14 | 1.391 (3) |
S1—O5 | 1.4606 (14) | C9—C10 | 1.396 (3) |
S1—C5 | 1.7614 (18) | C10—N2 | 1.379 (3) |
C1—C2 | 1.400 (3) | C10—C11 | 1.389 (3) |
C1—C6 | 1.401 (2) | C11—C12 | 1.365 (3) |
C1—C7 | 1.477 (3) | C11—H11 | 0.9300 |
C2—O3 | 1.352 (2) | C12—C13 | 1.401 (3) |
C2—C3 | 1.389 (3) | C12—H12 | 0.9300 |
C3—C4 | 1.369 (3) | C13—C14 | 1.366 (3) |
C3—H3 | 0.9300 | C13—H13 | 0.9300 |
C4—C5 | 1.397 (3) | C14—H14 | 0.9300 |
C4—H4 | 0.9300 | N1—H1 | 0.86 (2) |
C5—C6 | 1.374 (3) | N2—H2 | 0.85 (2) |
C6—H6 | 0.9300 | O1—H1A | 0.81 (3) |
C7—O2 | 1.216 (2) | O3—H3A | 0.83 (3) |
C7—O1 | 1.316 (2) | O7—H7A | 0.82 (3) |
C8—N1 | 1.326 (2) | O7—H7B | 0.81 (3) |
C8—N2 | 1.328 (3) | O8—H8A | 0.86 (3) |
C8—C8i | 1.444 (4) | | |
| | | |
O6—S1—O4 | 111.82 (9) | N2—C10—C11 | 131.95 (18) |
O6—S1—O5 | 113.14 (9) | N2—C10—C9 | 106.26 (17) |
O4—S1—O5 | 110.35 (8) | C11—C10—C9 | 121.79 (18) |
O6—S1—C5 | 107.73 (9) | C12—C11—C10 | 116.39 (19) |
O4—S1—C5 | 107.07 (8) | C12—C11—H11 | 121.8 |
O5—S1—C5 | 106.36 (9) | C10—C11—H11 | 121.8 |
C2—C1—C6 | 118.90 (17) | C11—C12—C13 | 121.8 (2) |
C2—C1—C7 | 120.05 (17) | C11—C12—H12 | 119.1 |
C6—C1—C7 | 121.06 (17) | C13—C12—H12 | 119.1 |
O3—C2—C3 | 117.00 (18) | C14—C13—C12 | 122.5 (2) |
O3—C2—C1 | 123.03 (18) | C14—C13—H13 | 118.8 |
C3—C2—C1 | 119.97 (18) | C12—C13—H13 | 118.8 |
C4—C3—C2 | 120.63 (19) | C13—C14—C9 | 116.18 (18) |
C4—C3—H3 | 119.7 | C13—C14—H14 | 121.9 |
C2—C3—H3 | 119.7 | C9—C14—H14 | 121.9 |
C3—C4—C5 | 119.87 (19) | C8—N1—C9 | 108.73 (16) |
C3—C4—H4 | 120.1 | C8—N1—O7 | 119.61 (13) |
C5—C4—H4 | 120.1 | C9—N1—O7 | 131.52 (12) |
C6—C5—C4 | 120.23 (17) | C8—N1—H1 | 123.1 (14) |
C6—C5—S1 | 120.26 (14) | C9—N1—H1 | 127.8 (15) |
C4—C5—S1 | 119.50 (14) | C8—N2—C10 | 108.75 (16) |
C5—C6—C1 | 120.40 (17) | C8—N2—H2 | 125.4 (16) |
C5—C6—H6 | 119.8 | C10—N2—H2 | 125.7 (16) |
C1—C6—H6 | 119.8 | C7—O1—H1A | 108.1 (19) |
O2—C7—O1 | 122.82 (18) | C2—O3—H3A | 105 (2) |
O2—C7—C1 | 123.11 (18) | S1—O4—O7 | 120.51 (8) |
O1—C7—C1 | 114.07 (16) | S1—O6—O8 | 125.18 (9) |
N1—C8—N2 | 109.84 (17) | N1—O7—O4 | 87.23 (7) |
N1—C8—C8i | 125.5 (2) | N1—O7—H7A | 131 (2) |
N2—C8—C8i | 124.4 (2) | O4—O7—H7A | 121 (2) |
N1—C9—C14 | 132.19 (17) | N1—O7—H7B | 112 (2) |
N1—C9—C10 | 106.40 (16) | H7A—O7—H7B | 111 (3) |
C14—C9—C10 | 121.41 (18) | O6—O8—H8A | 112 (2) |
| | | |
C6—C1—C2—O3 | −179.14 (18) | C9—C10—C11—C12 | 0.6 (3) |
C7—C1—C2—O3 | 0.3 (3) | C10—C11—C12—C13 | −0.3 (3) |
C6—C1—C2—C3 | 0.7 (3) | C11—C12—C13—C14 | 0.2 (4) |
C7—C1—C2—C3 | −179.81 (19) | C12—C13—C14—C9 | −0.3 (3) |
O3—C2—C3—C4 | 179.3 (2) | N1—C9—C14—C13 | −179.3 (2) |
C1—C2—C3—C4 | −0.5 (3) | C10—C9—C14—C13 | 0.6 (3) |
C2—C3—C4—C5 | 0.1 (3) | N2—C8—N1—C9 | 1.1 (2) |
C3—C4—C5—C6 | 0.1 (3) | C8i—C8—N1—C9 | −174.22 (11) |
C3—C4—C5—S1 | 179.08 (17) | N2—C8—N1—O7 | −175.12 (13) |
O6—S1—C5—C6 | −20.47 (19) | C8i—C8—N1—O7 | 9.51 (18) |
O4—S1—C5—C6 | 99.96 (17) | C14—C9—N1—C8 | 179.3 (2) |
O5—S1—C5—C6 | −142.05 (16) | C10—C9—N1—C8 | −0.6 (2) |
O6—S1—C5—C4 | 160.58 (17) | C14—C9—N1—O7 | −5.0 (3) |
O4—S1—C5—C4 | −78.99 (18) | C10—C9—N1—O7 | 175.03 (13) |
O5—S1—C5—C4 | 38.99 (18) | N1—C8—N2—C10 | −1.2 (2) |
C4—C5—C6—C1 | 0.1 (3) | C8i—C8—N2—C10 | 174.23 (12) |
S1—C5—C6—C1 | −178.87 (14) | C11—C10—N2—C8 | −178.4 (2) |
C2—C1—C6—C5 | −0.5 (3) | C9—C10—N2—C8 | 0.8 (2) |
C7—C1—C6—C5 | −179.95 (18) | O6—S1—O4—O7 | 54.28 (11) |
C2—C1—C7—O2 | −0.1 (3) | O5—S1—O4—O7 | −178.86 (8) |
C6—C1—C7—O2 | 179.39 (18) | C5—S1—O4—O7 | −63.50 (11) |
C2—C1—C7—O1 | 179.84 (18) | O4—S1—O6—O8 | 106.13 (12) |
C6—C1—C7—O1 | −0.7 (3) | O5—S1—O6—O8 | −19.20 (14) |
N1—C9—C10—N2 | −0.1 (2) | C5—S1—O6—O8 | −136.48 (10) |
C14—C9—C10—N2 | 179.96 (17) | C8—N1—O7—O4 | −67.69 (15) |
N1—C9—C10—C11 | 179.18 (18) | C9—N1—O7—O4 | 117.03 (17) |
C14—C9—C10—C11 | −0.8 (3) | S1—O4—O7—N1 | −50.37 (10) |
N2—C10—C11—C12 | 179.6 (2) | | |
Symmetry code: (i) −x, y, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···O5ii | 0.81 (3) | 1.93 (3) | 2.725 (2) | 169 (3) |
N2—H2···O4i | 0.85 (2) | 1.94 (2) | 2.778 (2) | 169 (2) |
O8—H8A···O6i | 0.86 (3) | 2.10 (3) | 2.950 (2) | 171 (3) |
O3—H3A···O7iii | 0.83 (3) | 2.51 (3) | 3.057 (2) | 125 (3) |
O7—H7B···O2iii | 0.81 (3) | 2.58 (3) | 2.967 (2) | 111 (2) |
C14—H14···O3iii | 0.93 | 2.58 | 3.455 (3) | 156 |
O7—H7A···O5iv | 0.82 (3) | 1.98 (3) | 2.803 (2) | 178 (3) |
C12—H12···O6v | 0.93 | 2.49 | 3.404 (3) | 169 |
N1—H1···O7 | 0.86 (2) | 1.81 (2) | 2.666 (2) | 174 (2) |
O3—H3A···O2 | 0.83 (3) | 1.88 (3) | 2.633 (2) | 151 (3) |
O7—H7B···O4 | 0.81 (3) | 2.21 (3) | 2.838 (2) | 135 (3) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) x, −y+1, z+1/2; (iii) −x+1/2, −y+3/2, −z+1; (iv) x, y+1, z; (v) −x, −y+1, −z+1. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C6H8N42+·2C7H5O6S− | C14H12N42+·2C7H5O6S−·3H2O |
Mr | 570.5 | 724.66 |
Crystal system, space group | Triclinic, P1 | Monoclinic, C2/c |
Temperature (K) | 297 | 295 |
a, b, c (Å) | 5.4296 (5), 8.2995 (7), 12.7083 (11) | 25.0519 (9), 7.3158 (3), 17.0309 (6) |
α, β, γ (°) | 85.961 (2), 88.895 (2), 89.573 (1) | 90, 97.553 (3), 90 |
V (Å3) | 571.13 (9) | 3094.3 (2) |
Z | 1 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.31 | 0.26 |
Crystal size (mm) | 0.20 × 0.16 × 0.04 | 0.30 × 0.20 × 0.04 |
|
Data collection |
Diffractometer | Bruker SMART APEX CCD area-detector diffractometer | Bruker SMART APEX CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1997) | Multi-scan (SADABS; Sheldrick, 1997) |
Tmin, Tmax | 0.931, 0.988 | 0.918, 0.990 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6501, 2451, 1758 | 14378, 3008, 2489 |
Rint | 0.045 | 0.032 |
(sin θ/λ)max (Å−1) | 0.639 | 0.617 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.046, 0.146, 1.10 | 0.039, 0.118, 1.07 |
No. of reflections | 2451 | 3008 |
No. of parameters | 184 | 243 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.41, −0.30 | 0.29, −0.28 |
Hydrogen-bond geometry of the two title compounds (Å, °) topD—H···A | D—H | H···A | D···A | D—H···A |
(I) | | | | |
N1–H1···O5 | 0.86 (4) | 1.82 (4) | 2.660 (3) | 167 (3) |
N2–H2···O5i | 0.83 (3) | 2.10 (3) | 2.849 (3) | 150 (3) |
N2–H2···O2ii | 0.83 (3) | 2.40 (4) | 2.934 (3) | 123 (3) |
O1–H1A···O4iii | 0.83 (4) | 1.87 (4) | 2.681 (3) | 166 (4) |
O3–H3A···O3 | 0.83 (4) | 1.89 (4) | 2.624 (3) | 148 (4) |
C3–H3···O3iv | 0.93 | 2.50 | 3.424 (4) | 171 |
C6–H6···O1iii | 0.93 | 2.47 | 3.382 (4) | 168 |
C9–H9···O6v | 0.93 | 2.28 | 3.061 (4) | 141 |
(II) | | | | |
N1–H1···O7 | 0.862 (19) | 1.805 (19) | 2.664 (2) | 174 (2) |
N2–H2···O4vi | 0.846 (19) | 1.940 (19) | 2.775 (2) | 169 (2) |
O1–H1A···O5vii | 0.82 (2) | 1.92 (2) | 2.723 (2) | 167 (3) |
O3–H3A···O2 | 0.83 (3) | 1.87 (3) | 2.632 (2) | 152 (3) |
O3–H3A···O7viii | 0.83 (3) | 2.51 (3) | 3.055 (3) | 124 (3) |
O7–H7A···O5ix | 0.82 (2) | 1.99 (2) | 2.805 (2) | 178 (4) |
O7–H7B···O4 | 0.82 (3) | 2.21 (2) | 2.836 (2) | 134 (3) |
O7–H7B···O2viii | 0.82 (3) | 2.57 (3) | 2.967 (2) | 112 (2) |
O8–H8A···O6vi | 0.85 (3) | 2.11 (3) | 2.950 (2) | 171 (3) |
C12–H12···O6x | 0.93 | 2.48 | 3.402 (3) | 169 |
C14–H14···O3viii | 0.93 | 2.58 | 3.454 (3) | 156 |
Symmetry codes: (i) 2-x, -y, 1-z; (ii) 1+x, y, -1+z; (iii) -x, -y, 2-z;
(iv) 2-x, 1-y, 2-z; (v) 1-x, 1-y, 1-z; (vi) -x, y, 1/2-z; (vii) x, 1-y, 1/2+z;
(viii) 1/2-x, 3/2-y, 1-z; (ix) x, 1+y, z; (x) -x, 1-y, 1-z. |
In a continuation of our studies (Meng et al., 2007, 2008) of the molecular and supramolecular structures of organic salts formed by 5-sulfosaliyclic acid (5-H2SSA) and N-containing Lewis bases of 2,2'-bisimidazole (Bim) and 2,2'-bisbenzimidazole (Bbim), we report here the title compounds, (I) and (II).
In both compounds, the H atoms are transferred from the sulfonic acid group to the imidazole N atom, forming 1:2 organic salts (Lewis base to acid). However, there are some apparent differences between their crystallization behaviours. Firstly, compound (I) is anhydrous and crystallizes in space group P1. The two parts of the Bim2+ cation are related by an inversion centre at (1, 0, 1/2) and the dihedral angle between them is 0°. The asymmetric unit thus consists of half a Bim2+ cation and a 5-HSSA- anion (Fig. 1). In comparison, compound (II) crystallizes in the monoclinic system, space group C2/c. There is a two-fold screw axis lying at (0, y, 1/4) relating the two halves of the Bbim2+ cation, with a dihedral angle of 36.5 (1)° between them. There are also one and a half water molecules in the asymmetric unit (Fig. 2). Secondly, the conformations of the sulfonate groups with respect to their respective benzene rings are different in the two compounds. In (I), the plane defined by three sulfonate O atoms is twisted away from the benzene ring, with a dihedral angle of 88.5 (1)°. The perpendicular distances of each O atom to the benzene plane are ca 0.074 (1), 1.155 (1) and 1.219 (1) Å, respectively. However, the corresponding angles and distances in (II) are 89.4 (1)° and ca 0.439 (1), 0.841 (1) and 1.398 (1) Å. The spatial differences between the cations and anions in the two compounds may be largely attributed to the involvement of the benzene rings of the Bbim2+ moiety forming π–π interactions.
In the packing structures of the title compounds, the ionic components are linked into three-dimensional networks by a combination of N—H···O, O—H···O and C—H···O hydrogen bonds. In (I), the supramolecular structure can be analysed in terms of two substructures. Firstly, via intermolecular hydrogen bonds N1—H1···O5, N2—H2···O5(2 - x, -y, 1 - z), N2—H2···O2(1 + x, y, -1 + z), O1—H1A···O4(-x, -y, 2 - z) and C6—H6···O1(-x, -y, 2 - z), the dications and anions are linked into two-dimensional layers running parallel to the (010) plane (Fig. 3). Secondly, the (010) layers are joined together by the combinatory actions of hydrogen bonds C3—H3···O3(2 - x, 1 - y, 2 - z) and C9—H9···O6(1 - x, 1 - y, 1 - z), forming a three-dimensional network (Fig. 3). Although no π–π interactions are observed between the imidazole and benzene rings of (I), the cations and anions each adopt an alternating homogeneous arrangement, i.e. the Bim2+ cations stack only on top of Bim2+ cations and 5-HSSA- anions stack only on top of 5-HSSA- anions.
Similar to the packing pattern in (I), the components in (II) are linked into a three-dimensional network by means of extensive hydrogen bonding (Table 1), and the Bbim2+ dications and 5-HSSA- anions also form a homogeneous arrangement (Fig. 4). However, analysis using PLATON (Spek, 2003) indicates that strong π–π interactions exist between symmetry-related benzene rings in these layers [centroid-to-centroid separation = 3.572 (2)/3.835 (2) Å, interplanar spacing = 3.421 (2)/3.520 (2) Å; symmetry codes: (-x, 1 - y, 1 - z)/(-x, 2 - y, 1 - z), respectively]. A search of the Cambridge Structural Database (CSD, Version 5.29; Allen, 2002) for organic compounds containing at least one 5-HSSA- anion and imidazole cation was conducted to determine the effect of the substitution of imidazole H atoms on the incorporation of water molecules into the crystal structure. Only one 1:1 salt formed by 5-sulfosaliyclic acid and imidazole was found to be anhydrous [CSD refcode HILNEW (Yang, 2007)]. The other three hits, consisting of substituted imidazole cations and 5-HSSA- anions, all incorporated one to three water molecules [refcodes CIKRUK (Hou, 2007), XEYZUX (Wang & Wei, 2007) and WUYRUD (Madarasz et al., 2002). Although no systematic rules can be drawn from the above, it can be speculated that the substitution of the imidazole H atoms by methyl, phenyl etc. may be in favour of water molecules being incorporated into these organic salts. We will study this potential correlation further.
In conclusion, two 1:2 organic salts formed by 5-H2SSA and imidazole derivatives are reported in this paper. In both compounds, the cations and anions adopt a homogeneous arrangement, forming alternating cation and anion layers. It was also found that substitution of imidazole H atoms by other groups may favour the cocrystallisation of water molecules into the crystal structure.