organic compounds
Guanidinium 3-carboxy-2,3-dihydroxypropanoate monohydrate
aSchool of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, bSchool of Chemical Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and cX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
*Correspondence e-mail: nornisah@usm.my, hkfun@usm.my
In the title hydrated salt, CH6N3+·C4H5O6−·H2O, the deprotonated carboxyl group is disordered over two positions with a site-occupancy ratio of 0.945 (3):0.055 (3). The bond lengths in the guanidinium cation are intermediate between normal C—N and C=N bond lengths, indicating significant delocalization in this species. In the anions and water molecules are linked into sheets parallel to the ab plane by intermolecular O—H⋯O hydrogen bonds. The linking of the anions and water molecules with the cations by intermolecular N—H⋯O hydrogen bonds creates a three-dimensional network.
Related literature
For general background to and applications of guanidine derivatives, see: Angyal & Warburton (1951); Raczyńska et al. (2003); Yamada et al. (2009). For closely related guanidinium structures, see: Najafpour et al. (2007); Pereira Silva et al. (2007). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2005); cell SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supporting information
10.1107/S1600536809037313/tk2542sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809037313/tk2542Isup2.hkl
Tartaric acid (1 mol) was dissolved in THF (10 ml) in a round bottom flask. In a separating funnel, guanidine carbonate (1 mol), 99 % [H2NC(=NH)NH2].2H2CO3, was dissolved in THF (10 ml) and three drops of concentrated HCl were added. The guanidine solution then was added drop-wise to the flask of tartaric acid with stirring. The reactant mixture was left stirring for 3 h at room temperature. The colourless single crystals formed were washed with THF and dried at 353 K.
Atom H1O2 was placed in a calculated position, with O—H = 0.82 Å and Uiso = 1.5Ueq(O), and was refined using a freely rotating O—H bond. The other H atoms were located from difference Fourier map and allowed to refine freely, range of C—H = 0.945 (13)–1.015 (13) Å. The carboxylate group is disordered over two positions with a site-occupancy ratio of 0.945 (3):0.055 (3). For the minor disordered component, only the C atom was refined anisotropically.
Data collection: APEX2 (Bruker, 2005); cell
SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme. Open bonds indicate the minor disordered component. | |
Fig. 2. Unit cell contents of (I) viewed along the a axis, showing the three-dimensional network. Only the major component of the anion is shown. H atoms not involved in intermolecular interactions (dashed lines) have been omitted for clarity. |
CH6N3+·C4H5O6−·H2O | Z = 2 |
Mr = 227.18 | F(000) = 240 |
Triclinic, P1 | Dx = 1.601 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.4588 (1) Å | Cell parameters from 6392 reflections |
b = 8.0931 (1) Å | θ = 2.6–32.6° |
c = 8.6423 (1) Å | µ = 0.15 mm−1 |
α = 72.415 (1)° | T = 100 K |
β = 71.620 (1)° | Block, colourless |
γ = 81.558 (1)° | 0.45 × 0.32 × 0.14 mm |
V = 471.18 (1) Å3 |
Bruker SMART APEXII CCD area-detector diffractometer | 3418 independent reflections |
Radiation source: fine-focus sealed tube | 3115 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.018 |
ϕ and ω scans | θmax = 32.6°, θmin = 2.6° |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −11→11 |
Tmin = 0.937, Tmax = 0.979 | k = −11→12 |
10837 measured reflections | l = −12→13 |
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)] = 0.034 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.093 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0471P)2 + 0.1755P] where P = (Fo2 + 2Fc2)/3 |
3418 reflections | (Δ/σ)max < 0.001 |
197 parameters | Δρmax = 0.49 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
CH6N3+·C4H5O6−·H2O | γ = 81.558 (1)° |
Mr = 227.18 | V = 471.18 (1) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.4588 (1) Å | Mo Kα radiation |
b = 8.0931 (1) Å | µ = 0.15 mm−1 |
c = 8.6423 (1) Å | T = 100 K |
α = 72.415 (1)° | 0.45 × 0.32 × 0.14 mm |
β = 71.620 (1)° |
Bruker SMART APEXII CCD area-detector diffractometer | 3418 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 3115 reflections with I > 2σ(I) |
Tmin = 0.937, Tmax = 0.979 | Rint = 0.018 |
10837 measured reflections |
R[F2 > 2σ(F2)] = 0.034 | 0 restraints |
wR(F2) = 0.093 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | Δρmax = 0.49 e Å−3 |
3418 reflections | Δρmin = −0.27 e Å−3 |
197 parameters |
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K. |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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 | Occ. (<1) | |
O1 | −0.00986 (9) | 0.73134 (10) | 0.50517 (8) | 0.02036 (14) | |
O2 | −0.09291 (9) | 0.54671 (9) | 0.76558 (8) | 0.01726 (13) | |
H1O2 | −0.2005 | 0.5811 | 0.7604 | 0.026* | |
O3 | 0.35923 (9) | 0.69520 (8) | 0.49515 (8) | 0.01562 (12) | |
O4 | 0.19600 (9) | 0.77452 (8) | 0.81295 (8) | 0.01573 (12) | |
C1 | 0.02941 (11) | 0.62976 (11) | 0.62883 (10) | 0.01333 (14) | |
C2 | 0.23376 (10) | 0.58428 (10) | 0.63385 (9) | 0.01179 (13) | |
C3 | 0.25872 (11) | 0.60619 (10) | 0.79571 (9) | 0.01189 (13) | |
C4 | 0.46665 (12) | 0.55432 (14) | 0.78966 (10) | 0.01126 (17) | 0.945 (3) |
O5 | 0.57222 (9) | 0.66863 (9) | 0.77930 (9) | 0.01673 (17) | 0.945 (3) |
O6 | 0.52211 (9) | 0.39998 (9) | 0.79084 (8) | 0.01420 (16) | 0.945 (3) |
C4A | 0.480 (3) | 0.606 (3) | 0.793 (2) | 0.01126 (17) | 0.055 (3) |
O5A | 0.503 (3) | 0.736 (3) | 0.823 (3) | 0.042 (5)* | 0.055 (3) |
O6A | 0.5654 (17) | 0.4820 (18) | 0.7605 (14) | 0.015 (3)* | 0.055 (3) |
N1 | 0.29076 (11) | 1.10920 (10) | −0.04338 (10) | 0.01787 (14) | |
N2 | 0.13002 (11) | 0.86542 (10) | 0.12497 (9) | 0.01554 (13) | |
N3 | 0.25830 (11) | 1.02160 (10) | 0.24365 (10) | 0.01706 (14) | |
C5 | 0.22818 (11) | 0.99832 (10) | 0.10812 (10) | 0.01293 (14) | |
O1W | 0.31892 (10) | 0.09289 (9) | 0.60724 (9) | 0.01863 (13) | |
H2A | 0.2663 (17) | 0.4572 (16) | 0.6371 (16) | 0.011 (3)* | |
H3A | 0.1831 (18) | 0.5272 (17) | 0.8903 (17) | 0.014 (3)* | |
H1O3 | 0.382 (2) | 0.660 (2) | 0.409 (2) | 0.032 (4)* | |
H1O4 | 0.261 (2) | 0.851 (2) | 0.731 (2) | 0.035 (4)* | |
H1N1 | 0.277 (2) | 1.093 (2) | −0.131 (2) | 0.029 (4)* | |
H2N1 | 0.356 (2) | 1.194 (2) | −0.0562 (19) | 0.024 (3)* | |
H1N2 | 0.112 (2) | 0.789 (2) | 0.219 (2) | 0.029 (4)* | |
H2N2 | 0.136 (2) | 0.8370 (19) | 0.0359 (19) | 0.023 (3)* | |
H1N3 | 0.325 (2) | 1.105 (2) | 0.233 (2) | 0.026 (3)* | |
H2N3 | 0.227 (2) | 0.944 (2) | 0.337 (2) | 0.025 (3)* | |
H1W1 | 0.417 (3) | 0.143 (2) | 0.551 (2) | 0.039 (4)* | |
H2W1 | 0.240 (2) | 0.154 (2) | 0.559 (2) | 0.036 (4)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0161 (3) | 0.0283 (3) | 0.0131 (3) | 0.0031 (2) | −0.0054 (2) | −0.0013 (2) |
O2 | 0.0102 (2) | 0.0224 (3) | 0.0168 (3) | −0.0034 (2) | −0.0044 (2) | −0.0001 (2) |
O3 | 0.0144 (3) | 0.0197 (3) | 0.0112 (2) | −0.0052 (2) | −0.00005 (19) | −0.0039 (2) |
O4 | 0.0180 (3) | 0.0138 (3) | 0.0148 (3) | −0.0006 (2) | −0.0026 (2) | −0.0054 (2) |
C1 | 0.0121 (3) | 0.0160 (3) | 0.0126 (3) | −0.0009 (2) | −0.0042 (2) | −0.0042 (3) |
C2 | 0.0100 (3) | 0.0140 (3) | 0.0113 (3) | −0.0016 (2) | −0.0027 (2) | −0.0032 (2) |
C3 | 0.0101 (3) | 0.0138 (3) | 0.0116 (3) | −0.0012 (2) | −0.0029 (2) | −0.0030 (2) |
C4 | 0.0101 (3) | 0.0143 (4) | 0.0099 (3) | −0.0040 (3) | −0.0026 (2) | −0.0027 (3) |
O5 | 0.0117 (3) | 0.0165 (3) | 0.0236 (3) | −0.0037 (2) | −0.0053 (2) | −0.0063 (2) |
O6 | 0.0133 (3) | 0.0135 (3) | 0.0157 (3) | −0.0003 (2) | −0.0044 (2) | −0.0040 (2) |
C4A | 0.0101 (3) | 0.0143 (4) | 0.0099 (3) | −0.0040 (3) | −0.0026 (2) | −0.0027 (3) |
N1 | 0.0182 (3) | 0.0184 (3) | 0.0147 (3) | −0.0050 (3) | −0.0037 (2) | −0.0003 (3) |
N2 | 0.0188 (3) | 0.0143 (3) | 0.0139 (3) | −0.0032 (2) | −0.0050 (2) | −0.0030 (2) |
N3 | 0.0212 (3) | 0.0164 (3) | 0.0156 (3) | −0.0027 (3) | −0.0073 (3) | −0.0043 (3) |
C5 | 0.0112 (3) | 0.0133 (3) | 0.0136 (3) | 0.0011 (2) | −0.0034 (2) | −0.0036 (2) |
O1W | 0.0148 (3) | 0.0186 (3) | 0.0192 (3) | −0.0026 (2) | −0.0058 (2) | 0.0013 (2) |
O1—C1 | 1.2246 (10) | C4—O5 | 1.2662 (12) |
O2—C1 | 1.3042 (10) | C4A—O6A | 1.17 (2) |
O2—H1O2 | 0.8200 | C4A—O5A | 1.20 (3) |
O3—C2 | 1.4169 (9) | N1—C5 | 1.3286 (10) |
O3—H1O3 | 0.840 (18) | N1—H1N1 | 0.844 (17) |
O4—C3 | 1.4101 (10) | N1—H2N1 | 0.859 (15) |
O4—H1O4 | 0.851 (18) | N2—C5 | 1.3355 (10) |
C1—C2 | 1.5258 (11) | N2—H1N2 | 0.846 (16) |
C2—C3 | 1.5319 (11) | N2—H2N2 | 0.854 (16) |
C2—H2A | 1.015 (13) | N3—C5 | 1.3303 (10) |
C3—C4 | 1.5347 (11) | N3—H1N3 | 0.865 (16) |
C3—C4A | 1.641 (18) | N3—H2N3 | 0.851 (15) |
C3—H3A | 0.945 (13) | O1W—H1W1 | 0.822 (19) |
C4—O6 | 1.2549 (12) | O1W—H2W1 | 0.842 (18) |
C1—O2—H1O2 | 109.5 | C4A—C3—H3A | 115.5 (10) |
C2—O3—H1O3 | 109.6 (11) | O6—C4—O5 | 124.13 (8) |
C3—O4—H1O4 | 110.8 (12) | O6—C4—C3 | 116.93 (8) |
O1—C1—O2 | 125.21 (8) | O5—C4—C3 | 118.92 (8) |
O1—C1—C2 | 121.76 (7) | O6A—C4A—O5A | 140 (2) |
O2—C1—C2 | 113.01 (7) | O6A—C4A—C3 | 110.4 (14) |
O3—C2—C1 | 111.04 (6) | O5A—C4A—C3 | 109.7 (16) |
O3—C2—C3 | 107.06 (6) | C5—N1—H1N1 | 121.2 (11) |
C1—C2—C3 | 110.81 (6) | C5—N1—H2N1 | 120.5 (10) |
O3—C2—H2A | 112.1 (7) | H1N1—N1—H2N1 | 118.0 (14) |
C1—C2—H2A | 109.1 (7) | C5—N2—H1N2 | 115.7 (11) |
C3—C2—H2A | 106.6 (7) | C5—N2—H2N2 | 118.2 (10) |
O4—C3—C2 | 111.00 (6) | H1N2—N2—H2N2 | 119.5 (14) |
O4—C3—C4 | 115.34 (7) | C5—N3—H1N3 | 120.5 (10) |
C2—C3—C4 | 106.58 (6) | C5—N3—H2N3 | 118.7 (10) |
O4—C3—C4A | 99.2 (7) | H1N3—N3—H2N3 | 119.9 (15) |
C2—C3—C4A | 114.6 (6) | N1—C5—N3 | 120.41 (8) |
C4—C3—C4A | 16.1 (7) | N1—C5—N2 | 119.70 (7) |
O4—C3—H3A | 107.2 (8) | N3—C5—N2 | 119.87 (7) |
C2—C3—H3A | 108.8 (8) | H1W1—O1W—H2W1 | 101.2 (17) |
C4—C3—H3A | 107.8 (8) | ||
O1—C1—C2—O3 | 10.22 (11) | C2—C3—C4—O6 | −62.98 (9) |
O2—C1—C2—O3 | −171.38 (7) | C4A—C3—C4—O6 | 175 (2) |
O1—C1—C2—C3 | 129.07 (8) | O4—C3—C4—O5 | −8.52 (11) |
O2—C1—C2—C3 | −52.53 (9) | C2—C3—C4—O5 | 115.16 (8) |
O3—C2—C3—O4 | 66.54 (8) | C4A—C3—C4—O5 | −7 (2) |
C1—C2—C3—O4 | −54.69 (8) | O4—C3—C4A—O6A | −172.1 (12) |
O3—C2—C3—C4 | −59.80 (8) | C2—C3—C4A—O6A | −53.8 (14) |
C1—C2—C3—C4 | 178.98 (7) | C4—C3—C4A—O6A | 9.2 (12) |
O3—C2—C3—C4A | −44.8 (7) | O4—C3—C4A—O5A | 6.8 (16) |
C1—C2—C3—C4A | −166.1 (7) | C2—C3—C4A—O5A | 125.0 (14) |
O4—C3—C4—O6 | 173.34 (7) | C4—C3—C4A—O5A | −172 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H1O2···O5i | 0.82 | 1.72 | 2.5272 (10) | 170 |
O3—H1O3···O6ii | 0.836 (16) | 1.832 (16) | 2.6564 (9) | 168.6 (16) |
O4—H1O4···O1Wiii | 0.852 (16) | 1.963 (16) | 2.7455 (10) | 152.1 (15) |
N1—H1N1···O1Wiv | 0.845 (16) | 2.184 (16) | 3.0019 (11) | 162.8 (15) |
N1—H2N1···O6iv | 0.859 (16) | 2.075 (16) | 2.8573 (11) | 151.2 (14) |
N2—H1N2···O1 | 0.844 (16) | 2.274 (16) | 3.0131 (10) | 146.3 (15) |
N2—H2N2···O4v | 0.854 (15) | 2.036 (15) | 2.8828 (10) | 170.7 (15) |
N3—H1N3···O5vi | 0.862 (16) | 2.049 (16) | 2.8973 (11) | 167.6 (15) |
N3—H2N3···O1 | 0.847 (16) | 2.441 (16) | 3.1540 (11) | 142.3 (14) |
N3—H2N3···O3 | 0.847 (16) | 2.345 (16) | 3.0410 (11) | 139.7 (14) |
O1W—H1W1···O3ii | 0.82 (2) | 2.14 (2) | 2.9051 (10) | 155.0 (15) |
O1W—H2W1···O1vii | 0.842 (16) | 1.984 (16) | 2.8100 (11) | 166.4 (16) |
Symmetry codes: (i) x−1, y, z; (ii) −x+1, −y+1, −z+1; (iii) x, y+1, z; (iv) x, y+1, z−1; (v) x, y, z−1; (vi) −x+1, −y+2, −z+1; (vii) −x, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | CH6N3+·C4H5O6−·H2O |
Mr | 227.18 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 100 |
a, b, c (Å) | 7.4588 (1), 8.0931 (1), 8.6423 (1) |
α, β, γ (°) | 72.415 (1), 71.620 (1), 81.558 (1) |
V (Å3) | 471.18 (1) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.15 |
Crystal size (mm) | 0.45 × 0.32 × 0.14 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.937, 0.979 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10837, 3418, 3115 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.758 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.093, 1.02 |
No. of reflections | 3418 |
No. of parameters | 197 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.49, −0.27 |
Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H1O2···O5i | 0.8200 | 1.7200 | 2.5272 (10) | 170.00 |
O3—H1O3···O6ii | 0.836 (16) | 1.832 (16) | 2.6564 (9) | 168.6 (16) |
O4—H1O4···O1Wiii | 0.852 (16) | 1.963 (16) | 2.7455 (10) | 152.1 (15) |
N1—H1N1···O1Wiv | 0.845 (16) | 2.184 (16) | 3.0019 (11) | 162.8 (15) |
N1—H2N1···O6iv | 0.859 (16) | 2.075 (16) | 2.8573 (11) | 151.2 (14) |
N2—H1N2···O1 | 0.844 (16) | 2.274 (16) | 3.0131 (10) | 146.3 (15) |
N2—H2N2···O4v | 0.854 (15) | 2.036 (15) | 2.8828 (10) | 170.7 (15) |
N3—H1N3···O5vi | 0.862 (16) | 2.049 (16) | 2.8973 (11) | 167.6 (15) |
N3—H2N3···O1 | 0.847 (16) | 2.441 (16) | 3.1540 (11) | 142.3 (14) |
N3—H2N3···O3 | 0.847 (16) | 2.345 (16) | 3.0410 (11) | 139.7 (14) |
O1W—H1W1···O3ii | 0.82 (2) | 2.14 (2) | 2.9051 (10) | 155.0 (15) |
O1W—H2W1···O1vii | 0.842 (16) | 1.984 (16) | 2.8100 (11) | 166.4 (16) |
Symmetry codes: (i) x−1, y, z; (ii) −x+1, −y+1, −z+1; (iii) x, y+1, z; (iv) x, y+1, z−1; (v) x, y, z−1; (vi) −x+1, −y+2, −z+1; (vii) −x, −y+1, −z+1. |
Footnotes
‡Thomson Reuters ResearcherID: A-3561-2009.
Acknowledgements
This research was supported by Universiti Sains Malaysia (USM) under a Short Term Grant (No. 304/PKIMIA/639039). HKF and JHG thank USM for a Research University Golden Goose grant (No. 1001/PFIZIK/811012). JHG also thanks USM for the award of a USM fellowship.
References
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Guanidine, formed by the oxidation of guanine, is a strongly alkaline compound that can be used in the manufacturing of plastics and explosives. It is also the final product of the protein metabolism. Interest in this molecule spans many generations of chemists (Angyal & Warburton, 1951; Raczyńska et al., 2003; Yamada et al., 2009).
The asymmetric unit of the title salt (Fig. 1) contains a guanidinium cation, a 3-carboxy-2,3-dihydroxypropanoate anion and a water molecule. A proton transfer from the carboxyl group of 3-carboxy-2,3-dihydroxypropanoic acid to atom N1 of guanidine resulted in the formation of ions. The deprotonated carboxyl group is disordered over two positions with a site-occupancy ratio of 0.945 (3):0.055 (3). The C5—N1, C5—N2 and C5—N3 bond lengths in the propeller-shaped guanidinium cation (CN3H6)+ are almost equal [range of C—N = 1.3286 (10) – 1.3355 (10) Å], indicating that the usual model of electron dislocalization in this species (Allen et al., 1987). The bond lengths and angles are comparable to those found in closely related structures (Najafpour et al., 2007; Pereira Silva et al., 2007).
The crystal structure is mainly stabilized by a network of O—H···O and N—H···O hydrogen bonds. In this network, the O atoms of anion and water molecule act as donors as well as acceptors. Each guanidinium-H atom participates in intermolecular hydrogen bonds. In the crystal structure (Fig. 2), the anions and water molecules are linked into sheets parallel to the ab plane by intermolecular O2—H1O2···O5, O3—H1O3···O6, O4—H1O4···O1W, O1W—H1W1···O3 and O1W—H2W1···O1 hydrogen bonds (Table 1). The anions and water molecules are further linked with the cations by intermolecular N1—H1N1···O1W, N1—H2N1···O6, N2—H1N2···O1, N2—H2N2···O4, N3—H1N3···O5, N3—H2N3···O1 and N3—H2N3···O3 hydrogen bonds (Table 1), thus establishing a connection between these sheets to create a three-dimensional crystal structure.