organic compounds
Bis(imidazolium) galactarate dihydrate
aFaculty of Science and Technology, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia
*Correspondence e-mail: g.smith@qut.edu.au
In the structure of the title salt, 2C3H5N2+·C6H8O82−·2H2O, the galactarate dianions have crystallographic inversion symmetry and together with the water molecules of solvation form hydrogen-bonded sheet substructures which extend along (110). The imidazolium cations link these sheets peripherally down c through carboxylate O—H—N and N′—H⋯Ohydroxy bridges, giving a three-dimensional framework structure.
Related literature
For mention of mucic acid in the Merck Index, see: O'Neil (2001). For the structures of imidazolium hydrogen salts of aliphatic dicarboxylic acids, see: James & Matsushima (1976); MacDonald et al. (2001); Aakeröy & Hitchcock (1993); Fuller et al. (1995); Fukunaga & Ishida (2003); Trivedi et al. (2003). For the structures of galactaric acid, ammonium H galactarate, diammonium galactarate and copper(II) galactarate dihydrate, see: Jeffrey & Wood (1982), Bontchev & Moore (2005), Benetollo et al. (1993) and Ferrier et al. (1998) respectively. For graph-set analysis, see: Etter et al. (1990).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON.
Supporting information
https://doi.org/10.1107/S1600536810033532/ng5021sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810033532/ng5021Isup2.hkl
The title compound was synthesized by heating together under reflux for 10 minutes 1 mmol of galactaric acid (mucic acid) and 2 mmol of imidazole in 50 ml of 50% ethanol-water. After concentration to ca 30 ml, partial room temperature evaporation of the hot-filtered solution gave large colourless plates of (I) (m.p. 435 K) from which a suitable analytical specimen was cleaved.
Hydrogen atoms potentially involved in hydrogen-bonding interactions were located by difference methods and their positional and isotropic displacement parameters were refined. Other H atoms were included in the
in calculated positions (C–Haromatic = 0.95 Å and others = 1.00 Å) and allowed to ride, with Uiso(H) = 1.2Ueq(C).Galactaric acid (mucic acid) (O'Neil, 2001) is the C6 homologue of tartaric acid but differs from it in being achiral and as well has only a small number of representative crystal structures in the CSD, e.g. the acid itself (Jeffrey & Wood, 1982), ammonium hydrogen galactarate (Bontchev & Moore, 2005), diammonium galactarate (Benetollo et al., 1993) and some metal complexes, e.g. copper(II) galactarate dihydrate (a fungicide) (Ferrier et al., 1998). Because the imidazolium cation has proved to be an excellent linking molecule for the generation of supramolecular layered structures particularly with dicarboxylic acids, including hydroxy acids (James & Matsushima, 1976; MacDonald et al., 2001; Aakeröy & Hitchcock, 1993; Fuller et al., 1995; Fukunaga & Ishida, 2003; Trivedi et al., 2003), we carried out a 1:2 stoichiometric reaction of galactaric acid with imidazole in aqueous ethanol and obtained large relatively hard, chemically stable crystals of the title compound, 2(CH6N3+) C6H8O82-. 2H2O (I), and the structure is reported here.
In the structure of (I) (Fig. 1), the galactarate anions lie across crystallographic inversion centres which is also the case in the structure of the parent acid (Jeffrey & Wood, 1982). Hydrogen-bonded anion-water sheets extending across the <100> planes in the
(Fig. 2) are formed through hydroxyl O31–H···O12iiicarboxyl and water-bridging O31···O11ivcarboxyl interactions (for symmetry codes, see Table 1). These include R22(12) and R33(12) cyclic motifs (Etter et al., 1990). The layered substructures are linked peripherally down the c cell direction by the imidazolium cations through carboxyl O···H—N,N'—H···O`hydroxyl bridges giving a three-dimensional framework structure (Fig. 3). The structure of (I) differs from those of the anhydrous 1:1 salts of the hydrogen dicarboxylates (MacDonald et al., 2001) in which the bridging imidazolium cations are incorporated within two-dimensional layered structures.For mention of mucic acid in the Merck Index, see: O'Neil (2001). For the structures of imidazolium hydrogen salts of aliphatic dicarboxylic acids, see: James & Matsushima (1976); MacDonald et al. (2001); Aakeröy & Hitchcock (1993); Fuller et al. (1995); Fukunaga & Ishida (2003); Trivedi et al. (2003). For the structures of galactaric acid, ammonium H galactarate, diammonium galactarate and copper(II) galactarate dihydrate, see: Jeffrey & Wood (1982), Bontchev & Moore (2005), Benetollo et al. (1993) and Ferrier et al. (1998) respectively. For graph-set analysis, see: Etter et al. (1990).
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell
CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).Fig. 1. The molecular configuration and atom-numbering scheme for the cation, dianion and water species in (I). The galactarate dianion has inversion symmetry [symmetry code: (i) -x + 1, -y + 1, -z + 2]. Non-H atoms are shown as 50% probability ellipsoids and inter-species hydrogen bonds are shown as dashed lines. | |
Fig. 2. Hydrogen-bonded anion-water sheet substructures in (I), extending across (110) (imidazolium cations are omitted). For symmetry codes, see Table 1. Hydrogen bonds are shown as dashed lines. | |
Fig. 3. The three-dimensional structure of (I) viewed down the approximate a cell direction, showing the imidazolium bridges. |
2C3H5N2+·C6H8O82−·2H2O | Z = 1 |
Mr = 382.34 | F(000) = 202 |
Triclinic, P1 | Dx = 1.494 Mg m−3 |
Hall symbol: -P 1 | Melting point: 435 K |
a = 6.9184 (4) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 7.1336 (4) Å | Cell parameters from 3387 reflections |
c = 9.3652 (5) Å | θ = 3.5–28.7° |
α = 92.000 (5)° | µ = 0.13 mm−1 |
β = 100.559 (5)° | T = 200 K |
γ = 109.835 (6)° | Plate, colourless |
V = 425.06 (5) Å3 | 0.45 × 0.45 × 0.30 mm |
Oxford Diffraction Gemini-S CCD-detector diffractometer | 1657 independent reflections |
Radiation source: Enhance (Mo) X-ray source | 1431 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.019 |
ω scans | θmax = 26.0°, θmin = 3.5° |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | h = −8→8 |
Tmin = 0.965, Tmax = 0.980 | k = −8→8 |
4949 measured reflections | l = −11→11 |
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)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.082 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.13 | w = 1/[σ2(Fo2) + (0.0444P)2 + 0.0516P] where P = (Fo2 + 2Fc2)/3 |
1657 reflections | (Δ/σ)max = 0.001 |
142 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.20 e Å−3 |
2C3H5N2+·C6H8O82−·2H2O | γ = 109.835 (6)° |
Mr = 382.34 | V = 425.06 (5) Å3 |
Triclinic, P1 | Z = 1 |
a = 6.9184 (4) Å | Mo Kα radiation |
b = 7.1336 (4) Å | µ = 0.13 mm−1 |
c = 9.3652 (5) Å | T = 200 K |
α = 92.000 (5)° | 0.45 × 0.45 × 0.30 mm |
β = 100.559 (5)° |
Oxford Diffraction Gemini-S CCD-detector diffractometer | 1657 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) | 1431 reflections with I > 2σ(I) |
Tmin = 0.965, Tmax = 0.980 | Rint = 0.019 |
4949 measured reflections |
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.082 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.13 | Δρmax = 0.30 e Å−3 |
1657 reflections | Δρmin = −0.20 e Å−3 |
142 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
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 | ||
O11 | 0.18384 (15) | −0.07229 (13) | 0.80626 (9) | 0.0234 (3) | |
O12 | 0.26773 (14) | −0.02982 (13) | 1.04961 (9) | 0.0207 (3) | |
O21 | 0.19607 (14) | 0.29951 (14) | 0.78260 (9) | 0.0203 (3) | |
O31 | 0.62559 (14) | 0.35914 (13) | 0.90945 (10) | 0.0197 (3) | |
C1 | 0.23436 (18) | 0.03283 (17) | 0.92558 (13) | 0.0154 (3) | |
C2 | 0.25848 (18) | 0.25478 (17) | 0.92684 (12) | 0.0151 (3) | |
C3 | 0.48566 (18) | 0.38863 (17) | 0.99549 (13) | 0.0153 (3) | |
N11 | 0.34766 (19) | 0.22454 (18) | 0.54570 (12) | 0.0261 (4) | |
N31 | 0.35478 (19) | 0.13600 (18) | 0.32587 (12) | 0.0265 (4) | |
C21 | 0.2302 (2) | 0.1404 (2) | 0.41585 (14) | 0.0269 (4) | |
C41 | 0.5588 (2) | 0.2202 (2) | 0.40018 (15) | 0.0302 (5) | |
C51 | 0.5544 (2) | 0.2764 (2) | 0.53780 (15) | 0.0285 (4) | |
O1W | −0.02769 (16) | 0.53271 (15) | 0.78655 (11) | 0.0244 (3) | |
H22 | 0.118 (3) | 0.373 (3) | 0.7852 (19) | 0.046 (5)* | |
H2 | 0.16380 | 0.28050 | 0.98780 | 0.0180* | |
H3 | 0.52450 | 0.35200 | 1.09610 | 0.0180* | |
H32 | 0.657 (3) | 0.260 (3) | 0.9315 (18) | 0.040 (5)* | |
H11 | 0.301 (3) | 0.245 (3) | 0.625 (2) | 0.048 (5)* | |
H21 | 0.08100 | 0.09150 | 0.39160 | 0.0320* | |
H31 | 0.318 (3) | 0.084 (3) | 0.233 (2) | 0.044 (5)* | |
H41 | 0.68070 | 0.23610 | 0.36180 | 0.0360* | |
H51 | 0.67240 | 0.34010 | 0.61480 | 0.0340* | |
H11W | 0.043 (3) | 0.660 (4) | 0.803 (2) | 0.057 (6)* | |
H12W | −0.127 (4) | 0.500 (3) | 0.835 (2) | 0.059 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O11 | 0.0320 (5) | 0.0168 (5) | 0.0185 (5) | 0.0058 (4) | 0.0047 (4) | −0.0032 (4) |
O12 | 0.0290 (5) | 0.0158 (5) | 0.0174 (4) | 0.0077 (4) | 0.0056 (4) | 0.0024 (3) |
O21 | 0.0257 (5) | 0.0230 (5) | 0.0157 (5) | 0.0135 (4) | 0.0032 (4) | 0.0023 (4) |
O31 | 0.0214 (5) | 0.0149 (5) | 0.0265 (5) | 0.0079 (4) | 0.0113 (4) | 0.0032 (4) |
C1 | 0.0129 (6) | 0.0148 (6) | 0.0174 (6) | 0.0026 (5) | 0.0051 (4) | 0.0001 (5) |
C2 | 0.0185 (6) | 0.0143 (6) | 0.0132 (6) | 0.0058 (5) | 0.0049 (5) | 0.0009 (5) |
C3 | 0.0185 (6) | 0.0136 (6) | 0.0144 (6) | 0.0052 (5) | 0.0054 (5) | 0.0017 (5) |
N11 | 0.0347 (7) | 0.0308 (7) | 0.0175 (6) | 0.0160 (5) | 0.0084 (5) | 0.0031 (5) |
N31 | 0.0379 (7) | 0.0260 (6) | 0.0152 (6) | 0.0116 (5) | 0.0044 (5) | 0.0010 (5) |
C21 | 0.0273 (7) | 0.0304 (8) | 0.0230 (7) | 0.0104 (6) | 0.0043 (6) | 0.0070 (6) |
C41 | 0.0311 (8) | 0.0336 (8) | 0.0301 (8) | 0.0134 (6) | 0.0120 (6) | 0.0064 (6) |
C51 | 0.0286 (7) | 0.0294 (8) | 0.0241 (7) | 0.0085 (6) | 0.0007 (6) | 0.0004 (6) |
O1W | 0.0231 (5) | 0.0180 (5) | 0.0325 (6) | 0.0063 (4) | 0.0095 (4) | −0.0005 (4) |
O11—C1 | 1.2465 (15) | N11—H11 | 0.89 (2) |
O12—C1 | 1.2690 (15) | N31—H31 | 0.890 (18) |
O21—C2 | 1.4223 (14) | C1—C2 | 1.5341 (16) |
O31—C3 | 1.4293 (16) | C2—C3 | 1.5375 (18) |
O21—H22 | 0.87 (2) | C3—C3i | 1.5303 (16) |
O31—H32 | 0.83 (2) | C2—H2 | 1.0000 |
O1W—H11W | 0.87 (3) | C3—H3 | 1.0000 |
O1W—H12W | 0.86 (3) | C41—C51 | 1.345 (2) |
N11—C21 | 1.3249 (17) | C21—H21 | 0.9500 |
N11—C51 | 1.367 (2) | C41—H41 | 0.9500 |
N31—C21 | 1.3178 (19) | C51—H51 | 0.9500 |
N31—C41 | 1.369 (2) | ||
C2—O21—H22 | 108.6 (11) | O31—C3—C3i | 107.52 (10) |
C3—O31—H32 | 110.6 (13) | O21—C2—H2 | 108.00 |
H11W—O1W—H12W | 111 (2) | C3—C2—H2 | 108.00 |
C21—N11—C51 | 108.65 (12) | C1—C2—H2 | 108.00 |
C21—N31—C41 | 108.66 (11) | O31—C3—H3 | 109.00 |
C51—N11—H11 | 125.3 (14) | C2—C3—H3 | 109.00 |
C21—N11—H11 | 126.1 (14) | C3i—C3—H3 | 109.00 |
C41—N31—H31 | 123.6 (14) | N11—C21—N31 | 108.63 (13) |
C21—N31—H31 | 127.7 (14) | N31—C41—C51 | 107.15 (13) |
O12—C1—C2 | 116.02 (10) | N11—C51—C41 | 106.92 (12) |
O11—C1—O12 | 124.82 (11) | N31—C21—H21 | 126.00 |
O11—C1—C2 | 119.16 (10) | N11—C21—H21 | 126.00 |
O21—C2—C3 | 111.32 (10) | N31—C41—H41 | 126.00 |
O21—C2—C1 | 110.05 (9) | C51—C41—H41 | 126.00 |
C1—C2—C3 | 110.45 (10) | N11—C51—H51 | 127.00 |
O31—C3—C2 | 109.98 (9) | C41—C51—H51 | 127.00 |
C2—C3—C3i | 112.11 (10) | ||
C21—N11—C51—C41 | −0.42 (16) | C1—C2—C3—C3i | −177.68 (10) |
C51—N11—C21—N31 | 0.31 (16) | C1—C2—C3—O31 | 62.76 (12) |
C21—N31—C41—C51 | −0.19 (16) | O21—C2—C3—C3i | 59.76 (13) |
C41—N31—C21—N11 | −0.08 (16) | O31—C3—C3i—O31i | 179.98 (12) |
O11—C1—C2—O21 | 5.67 (17) | C2—C3—C3i—O31i | 59.01 (12) |
O12—C1—C2—O21 | −174.06 (11) | C2—C3—C3i—C2i | −179.98 (12) |
O12—C1—C2—C3 | 62.63 (14) | O31—C3—C3i—C2i | −59.01 (12) |
O11—C1—C2—C3 | −117.63 (13) | N31—C41—C51—N11 | 0.36 (16) |
O21—C2—C3—O31 | −59.81 (13) |
Symmetry code: (i) −x+1, −y+1, −z+2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H11···O21 | 0.89 (2) | 1.84 (2) | 2.7311 (15) | 175.9 (19) |
N31—H31···O12ii | 0.890 (18) | 1.795 (19) | 2.6810 (14) | 174 (2) |
O21—H22···O1W | 0.87 (2) | 1.76 (2) | 2.6324 (15) | 177 (2) |
O31—H32···O12iii | 0.83 (2) | 1.89 (2) | 2.7104 (13) | 170.9 (16) |
O1W—H11W···O11iv | 0.87 (3) | 1.82 (3) | 2.6799 (14) | 170.9 (18) |
O1W—H12W···O31v | 0.86 (3) | 1.94 (3) | 2.7763 (15) | 164.4 (19) |
C21—H21···O11vi | 0.95 | 2.32 | 3.0935 (17) | 138 |
C41—H41···O11vii | 0.95 | 2.42 | 3.2273 (18) | 142 |
C51—H51···O1Wviii | 0.95 | 2.34 | 3.2827 (18) | 173 |
Symmetry codes: (ii) x, y, z−1; (iii) −x+1, −y, −z+2; (iv) x, y+1, z; (v) x−1, y, z; (vi) −x, −y, −z+1; (vii) −x+1, −y, −z+1; (viii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | 2C3H5N2+·C6H8O82−·2H2O |
Mr | 382.34 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 200 |
a, b, c (Å) | 6.9184 (4), 7.1336 (4), 9.3652 (5) |
α, β, γ (°) | 92.000 (5), 100.559 (5), 109.835 (6) |
V (Å3) | 425.06 (5) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 0.13 |
Crystal size (mm) | 0.45 × 0.45 × 0.30 |
Data collection | |
Diffractometer | Oxford Diffraction Gemini-S CCD-detector |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2010) |
Tmin, Tmax | 0.965, 0.980 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4949, 1657, 1431 |
Rint | 0.019 |
(sin θ/λ)max (Å−1) | 0.616 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.082, 1.13 |
No. of reflections | 1657 |
No. of parameters | 142 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.30, −0.20 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999), PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H11···O21 | 0.89 (2) | 1.84 (2) | 2.7311 (15) | 175.9 (19) |
N31—H31···O12i | 0.890 (18) | 1.795 (19) | 2.6810 (14) | 174 (2) |
O21—H22···O1W | 0.87 (2) | 1.76 (2) | 2.6324 (15) | 177 (2) |
O31—H32···O12ii | 0.83 (2) | 1.89 (2) | 2.7104 (13) | 170.9 (16) |
O1W—H11W···O11iii | 0.87 (3) | 1.82 (3) | 2.6799 (14) | 170.9 (18) |
O1W—H12W···O31iv | 0.86 (3) | 1.94 (3) | 2.7763 (15) | 164.4 (19) |
Symmetry codes: (i) x, y, z−1; (ii) −x+1, −y, −z+2; (iii) x, y+1, z; (iv) x−1, y, z. |
Acknowledgements
The authors acknowledge financial support from the Australian Research Committee and the Faculty of Science and Technology, Queensland University of Technology.
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Galactaric acid (mucic acid) (O'Neil, 2001) is the C6 homologue of tartaric acid but differs from it in being achiral and as well has only a small number of representative crystal structures in the CSD, e.g. the acid itself (Jeffrey & Wood, 1982), ammonium hydrogen galactarate (Bontchev & Moore, 2005), diammonium galactarate (Benetollo et al., 1993) and some metal complexes, e.g. copper(II) galactarate dihydrate (a fungicide) (Ferrier et al., 1998). Because the imidazolium cation has proved to be an excellent linking molecule for the generation of supramolecular layered structures particularly with dicarboxylic acids, including hydroxy acids (James & Matsushima, 1976; MacDonald et al., 2001; Aakeröy & Hitchcock, 1993; Fuller et al., 1995; Fukunaga & Ishida, 2003; Trivedi et al., 2003), we carried out a 1:2 stoichiometric reaction of galactaric acid with imidazole in aqueous ethanol and obtained large relatively hard, chemically stable crystals of the title compound, 2(CH6N3+) C6H8O82-. 2H2O (I), and the structure is reported here.
In the structure of (I) (Fig. 1), the galactarate anions lie across crystallographic inversion centres which is also the case in the structure of the parent acid (Jeffrey & Wood, 1982). Hydrogen-bonded anion-water sheets extending across the <100> planes in the unit cell (Fig. 2) are formed through hydroxyl O31–H···O12iiicarboxyl and water-bridging O31···O11ivcarboxyl interactions (for symmetry codes, see Table 1). These include R22(12) and R33(12) cyclic motifs (Etter et al., 1990). The layered substructures are linked peripherally down the c cell direction by the imidazolium cations through carboxyl O···H—N,N'—H···O`hydroxyl bridges giving a three-dimensional framework structure (Fig. 3). The structure of (I) differs from those of the anhydrous 1:1 salts of the hydrogen dicarboxylates (MacDonald et al., 2001) in which the bridging imidazolium cations are incorporated within two-dimensional layered structures.