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Acta Cryst. (2009). E65, m1540-m1541    [ doi:10.1107/S1600536809046170 ]

Tetraguanidinium bis[citrato(3-)]cuprate(II) dihydrate

M. T. M. Al-Dajani, H. H. Abdallah, N. Mohamed, C. S. Yeap and H.-K. Fun

Abstract top

The asymmetric unit of the title compound, (CH6N3)4[Cu(C6H5O7)2]·2H2O, contains one-half of a centrosymmetric CuII complex anion, two guanidinium cations and a water molecule. The CuII ion, lying on a crystallographic inversion center, is hexacoordinated with two citrate anions in a distorted octahedral geometry. An intramolecular O-H...O hydrogen bond generates an S(6) ring motif. In the crystal structure, molecules are linked into a three-dimensional framework by intermolecular N-H...O and O-H...O hydrogen bonds.

Comment top

Citric acid or 2-hydroxy-1,2,3-propanetricarboxylic acid contains three carboxyl groups. It is an intermediate in the citric acid cycle in living organisms. It can be added to the food and soft drinks to add a sour or an acidic taste. Guanidine can be formed by the oxidation of guanine as a final product of the protein metabolism. The copper(II) ion in this crystal is coordinated to two citrate ions by the oxygen atoms and the four guanidinium ions neutralize the complex charge (Raczyńska et al., 2003; Yamada et al., 2009; Sigman et al., 1993).

The asymmetric unit of title compound contains half of a CuII complex anion, two guanidinium cations and a water solvent molecule, the other half is symmetry generated [symmetry code: -x + 1, -y + 2, -z + 1] (Fig. 1). The CuII ion lies on a crystallographic inversion center and is coordinated to six O atoms from two citrate anions to form an octahedral geometry. Four protons are deprotonated from two citric acid molecules to four guanidine molecules resulting in the formation of ions. The geometrical parameters of guanidinium cations agree with those previously reported (Al-Dajani et al., 2009). An intramolecular O3—H1O3···O6 hydrogen bond generates an S(6) ring motif (Bernstein et al., 1995).

In crystal structure (Fig. 2), all guanidinium N–H groups participate in the formation of a three-dimensional framework through N—H···O hydrogen bonds (Table 2). The structure are also stabilized by intermolecular O1W—H1W1···O4 and O1W—H2W1···O1 hydrogen bonds.

Related literature top

For general background to citric acid and guanidine, see: Raczyńska et al. (2003); Yamada et al. (2009); Sigman et al. (1993). For a related guanidinium structure, see: Al-Dajani et al. (2009). For hydrogen-bond motifs, see: Bernstein et al. (1995). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986).

Experimental top

Citric acid (anhydrous) (0.02 mol, 3.85 g) was dissolved in THF in a flat bottom flask with magnetic stirrer. In a separating funnel, guanidine carbonate (0.02 mol, 3.6 g), 99% [H2NC(NH)NH2].2H2CO3 was dissolved in THF. The guanidine solution was added in small portions to the flask of citric acid with stirring. The reaction mixture was refluxed for 1 h. After cooling the reaction mixture to room temperature, CuCl2 (0.01 mol, 1.45 g) was added with stirring for 3 h. Blue crystals formed were washed with N,N-dimethylformamide followed by methanol and dried at 353 K.

Refinement top

O-bound H atoms were located in a difference Fourier map and refined as riding on their parent atom, with Uiso(H) = 1.5Ueq(O). The remaining H atoms were positioned geometrically [C–H = 0.97 Å and N–H = 0.86 Å] and refined using a riding model, with Uiso(H) = 1.2Ueq(C,N).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: 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).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with atom labels and 30% probability ellipsoids for non-H atoms. Molecules/atoms with suffix A are generated by the symmetry operation (1-x, 2-y, 1-z). Intramolecular hydrogen bonds are shown as dashed lines.
[Figure 2] Fig. 2. The crystal packing of title compound, viewed down the a axis, showing hydrogen-bonded (dashed lines) three-dimensional framework.
Tetraguanidinium bis[citrato(3-)]cuprate(II) dihydrate top
Crystal data top
(CH6N3)4[Cu(C6H5O7)2]·2H2OZ = 1
Mr = 718.12F(000) = 375
Triclinic, P1Dx = 1.508 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 9.0426 (1) ÅCell parameters from 9680 reflections
b = 9.7763 (2) Åθ = 2.3–34.9°
c = 10.3366 (2) ŵ = 0.78 mm−1
α = 96.503 (1)°T = 296 K
β = 105.441 (1)°Block, blue
γ = 112.306 (1)°0.60 × 0.39 × 0.32 mm
V = 791.01 (2) Å3
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		7051 independent reflections
Radiation source: fine-focus sealed tube6306 reflections with I > 2σ(I)
graphiteRint = 0.024
φ and ω scansθmax = 35.3°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		h = −14→14
Tmin = 0.653, Tmax = 0.787k = −15→15
37237 measured reflectionsl = −16→16
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.094H-atom parameters constrained
S = 1.05 w = 1/[σ2(Fo2) + (0.0533P)2 + 0.108P]
where P = (Fo2 + 2Fc2)/3
7051 reflections(Δ/σ)max < 0.001
206 parametersΔρmax = 0.44 e Å−3
0 restraintsΔρmin = −0.49 e Å−3
Crystal data top
(CH6N3)4[Cu(C6H5O7)2]·2H2Oγ = 112.306 (1)°
Mr = 718.12V = 791.01 (2) Å3
Triclinic, P1Z = 1
a = 9.0426 (1) ÅMo Kα radiation
b = 9.7763 (2) ŵ = 0.78 mm−1
c = 10.3366 (2) ÅT = 296 K
α = 96.503 (1)°0.60 × 0.39 × 0.32 mm
β = 105.441 (1)°
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		7051 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		6306 reflections with I > 2σ(I)
Tmin = 0.653, Tmax = 0.787Rint = 0.024
37237 measured reflectionsθmax = 35.3°
Refinement top
R[F2 > 2σ(F2)] = 0.031H-atom parameters constrained
wR(F2) = 0.094Δρmax = 0.44 e Å−3
S = 1.05Δρmin = −0.49 e Å−3
7051 reflectionsAbsolute structure: ?
206 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
xyzUiso*/Ueq
Cu10.50001.00000.50000.02544 (5)
O10.66219 (12)0.89568 (10)0.55711 (9)0.04046 (18)
O20.55673 (11)1.02356 (8)0.33541 (8)0.03511 (15)
O30.32813 (9)0.77094 (8)0.36675 (7)0.02790 (12)
H1O30.22760.76610.30350.042*
O40.76260 (15)0.72314 (13)0.55564 (10)0.0536 (3)
O50.57936 (15)0.90234 (12)0.15326 (10)0.0506 (2)
O70.09687 (12)0.65390 (12)−0.05629 (9)0.04401 (19)
O60.10222 (13)0.74648 (13)0.15156 (9)0.0480 (2)
C10.66253 (14)0.77440 (12)0.49850 (10)0.03244 (18)
C20.53925 (14)0.68374 (11)0.35373 (10)0.03180 (18)
H2A0.46990.58260.36010.038*
H2B0.60520.67210.29660.038*
C30.42059 (12)0.74833 (10)0.27880 (9)0.02586 (14)
C40.52711 (13)0.90199 (11)0.25150 (10)0.02936 (16)
C50.29501 (13)0.63732 (12)0.14090 (10)0.03315 (18)
H5A0.35680.63130.07840.040*
H5B0.24320.53670.15670.040*
C60.15557 (13)0.68329 (13)0.07232 (11)0.03335 (18)
N10.33925 (19)0.13097 (19)0.12541 (16)0.0627 (4)
H1N10.39440.11030.07590.075*
H2N10.36250.12370.20990.075*
N20.13528 (17)0.20918 (16)0.14703 (11)0.0503 (3)
H1N20.05870.23900.11180.060*
H2N20.15770.20220.23160.060*
N30.18333 (18)0.18500 (18)−0.05808 (13)0.0548 (3)
H1N30.10670.2149−0.09290.066*
H2N30.23720.1622−0.10780.066*
C70.21821 (16)0.17412 (15)0.07130 (13)0.0409 (2)
N40.86185 (16)0.53693 (13)0.28012 (13)0.0475 (2)
H1N40.87430.62600.31630.057*
H2N40.88670.52230.20660.057*
N50.78586 (17)0.28597 (12)0.28065 (14)0.0506 (3)
H1N50.74860.21060.31710.061*
H2N50.81110.27270.20710.061*
N60.76591 (17)0.44356 (13)0.45058 (12)0.0469 (2)
H1N60.72860.36870.48750.056*
H2N60.77820.53240.48720.056*
C80.80435 (14)0.42221 (12)0.33777 (12)0.03575 (19)
O1W0.9973 (2)0.13741 (17)0.59833 (19)0.0955 (6)
H1W10.99760.12250.52230.143*
H2W10.89450.06560.59020.143*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.03201 (8)0.02210 (7)0.02568 (7)0.01325 (6)0.01258 (6)0.00553 (5)
O10.0452 (4)0.0371 (4)0.0360 (4)0.0230 (3)0.0056 (3)−0.0025 (3)
O20.0494 (4)0.0258 (3)0.0361 (3)0.0148 (3)0.0244 (3)0.0102 (3)
O30.0326 (3)0.0312 (3)0.0270 (3)0.0169 (3)0.0150 (2)0.0095 (2)
O40.0671 (6)0.0638 (6)0.0356 (4)0.0484 (5)0.0001 (4)0.0013 (4)
O50.0680 (6)0.0506 (5)0.0475 (5)0.0245 (5)0.0415 (5)0.0142 (4)
O70.0438 (4)0.0615 (5)0.0297 (3)0.0260 (4)0.0114 (3)0.0117 (3)
O60.0495 (5)0.0745 (6)0.0368 (4)0.0434 (5)0.0156 (4)0.0118 (4)
C10.0374 (5)0.0347 (4)0.0283 (4)0.0200 (4)0.0097 (3)0.0055 (3)
C20.0381 (5)0.0299 (4)0.0298 (4)0.0209 (4)0.0075 (3)0.0030 (3)
C30.0307 (4)0.0259 (3)0.0257 (3)0.0156 (3)0.0118 (3)0.0055 (3)
C40.0349 (4)0.0310 (4)0.0297 (4)0.0173 (3)0.0166 (3)0.0097 (3)
C50.0345 (4)0.0344 (4)0.0302 (4)0.0184 (4)0.0081 (3)0.0007 (3)
C60.0317 (4)0.0402 (5)0.0306 (4)0.0168 (4)0.0118 (3)0.0095 (4)
N10.0661 (8)0.0851 (10)0.0603 (7)0.0545 (8)0.0185 (6)0.0314 (7)
N20.0583 (7)0.0732 (8)0.0362 (5)0.0412 (6)0.0187 (5)0.0210 (5)
N30.0626 (7)0.0884 (9)0.0431 (5)0.0535 (7)0.0265 (5)0.0286 (6)
C70.0425 (6)0.0463 (6)0.0403 (5)0.0248 (5)0.0127 (4)0.0160 (4)
N40.0615 (7)0.0363 (5)0.0504 (6)0.0167 (5)0.0300 (5)0.0196 (4)
N50.0674 (7)0.0337 (4)0.0606 (7)0.0170 (5)0.0423 (6)0.0136 (4)
N60.0701 (7)0.0422 (5)0.0486 (6)0.0307 (5)0.0365 (5)0.0214 (4)
C80.0382 (5)0.0329 (4)0.0413 (5)0.0146 (4)0.0197 (4)0.0144 (4)
O1W0.0812 (9)0.0655 (8)0.1106 (12)−0.0041 (7)0.0578 (9)−0.0212 (8)
Geometric parameters (Å, °) top
Cu1—O2i1.9169 (7)C5—H5B0.97
Cu1—O21.9169 (7)N1—C71.3292 (16)
Cu1—O12.0857 (8)N1—H1N10.86
Cu1—O1i2.0857 (8)N1—H2N10.86
Cu1—O3i2.2015 (7)N2—C71.3189 (17)
Cu1—O32.2016 (7)N2—H1N20.86
O1—C11.2704 (12)N2—H2N20.86
O2—C41.2798 (12)N3—C71.3162 (16)
O3—C31.4401 (11)N3—H1N30.86
O3—H1O30.95N3—H2N30.86
O4—C11.2432 (13)N4—C81.3255 (14)
O5—C41.2286 (12)N4—H1N40.86
O7—C61.2464 (13)N4—H2N40.86
O6—C61.2678 (13)N5—C81.3232 (15)
C1—C21.5261 (14)N5—H1N50.86
C2—C31.5273 (13)N5—H2N50.86
C2—H2A0.97N6—C81.3191 (15)
C2—H2B0.97N6—H1N60.86
C3—C51.5334 (13)N6—H2N60.86
C3—C41.5513 (13)O1W—H1W10.78
C5—C61.5234 (14)O1W—H2W10.90
C5—H5A0.97
O2i—Cu1—O2179.999 (1)O5—C4—C3119.72 (9)
O2i—Cu1—O189.36 (4)O2—C4—C3116.95 (8)
O2—Cu1—O190.64 (4)C6—C5—C3113.23 (8)
O2i—Cu1—O1i90.64 (4)C6—C5—H5A108.9
O2—Cu1—O1i89.36 (4)C3—C5—H5A108.9
O1—Cu1—O1i180.00 (3)C6—C5—H5B108.9
O2i—Cu1—O3i80.58 (3)C3—C5—H5B108.9
O2—Cu1—O3i99.42 (3)H5A—C5—H5B107.7
O1—Cu1—O3i97.62 (3)O7—C6—O6123.57 (10)
O1i—Cu1—O3i82.38 (3)O7—C6—C5119.46 (10)
O2i—Cu1—O399.42 (3)O6—C6—C5116.94 (9)
O2—Cu1—O380.58 (3)C7—N1—H1N1120.0
O1—Cu1—O382.38 (3)C7—N1—H2N1120.0
O1i—Cu1—O397.62 (3)H1N1—N1—H2N1120.0
O3i—Cu1—O3180.0C7—N2—H1N2120.0
C1—O1—Cu1131.70 (7)C7—N2—H2N2120.0
C4—O2—Cu1116.90 (6)H1N2—N2—H2N2120.0
C3—O3—Cu1102.63 (5)C7—N3—H1N3120.0
C3—O3—H1O3103.2C7—N3—H2N3120.0
Cu1—O3—H1O3113.8H1N3—N3—H2N3120.0
O4—C1—O1122.02 (10)N3—C7—N2119.75 (11)
O4—C1—C2116.47 (9)N3—C7—N1119.69 (13)
O1—C1—C2121.51 (9)N2—C7—N1120.54 (12)
C1—C2—C3117.43 (7)C8—N4—H1N4120.0
C1—C2—H2A107.9C8—N4—H2N4120.0
C3—C2—H2A107.9H1N4—N4—H2N4120.0
C1—C2—H2B107.9C8—N5—H1N5120.0
C3—C2—H2B107.9C8—N5—H2N5120.0
H2A—C2—H2B107.2H1N5—N5—H2N5120.0
O3—C3—C2107.59 (7)C8—N6—H1N6120.0
O3—C3—C5109.31 (8)C8—N6—H2N6120.0
C2—C3—C5110.83 (7)H1N6—N6—H2N6120.0
O3—C3—C4110.36 (7)N6—C8—N5120.42 (10)
C2—C3—C4109.34 (8)N6—C8—N4120.42 (11)
C5—C3—C4109.39 (8)N5—C8—N4119.15 (11)
O5—C4—O2123.33 (10)H1W1—O1W—H2W1101.6
O2i—Cu1—O1—C1118.93 (11)Cu1—O3—C3—C4−32.73 (8)
O2—Cu1—O1—C1−61.07 (11)C1—C2—C3—O3−55.52 (11)
O3i—Cu1—O1—C1−160.66 (11)C1—C2—C3—C5−174.99 (9)
O3—Cu1—O1—C119.33 (11)C1—C2—C3—C464.35 (11)
O1—Cu1—O2—C458.64 (8)Cu1—O2—C4—O5−169.11 (10)
O1i—Cu1—O2—C4−121.36 (8)Cu1—O2—C4—C310.43 (12)
O3i—Cu1—O2—C4156.47 (8)O3—C3—C4—O5−161.50 (10)
O3—Cu1—O2—C4−23.53 (8)C2—C3—C4—O580.34 (12)
O2i—Cu1—O3—C3−149.08 (5)C5—C3—C4—O5−41.19 (13)
O2—Cu1—O3—C330.92 (5)O3—C3—C4—O218.95 (12)
O1—Cu1—O3—C3−61.01 (5)C2—C3—C4—O2−99.21 (10)
O1i—Cu1—O3—C3118.99 (5)C5—C3—C4—O2139.26 (9)
Cu1—O1—C1—O4−173.35 (10)O3—C3—C5—C652.33 (11)
Cu1—O1—C1—C26.55 (17)C2—C3—C5—C6170.76 (9)
O4—C1—C2—C3−177.27 (11)C4—C3—C5—C6−68.62 (10)
O1—C1—C2—C32.83 (16)C3—C5—C6—O7147.04 (11)
Cu1—O3—C3—C286.49 (7)C3—C5—C6—O6−34.97 (14)
Cu1—O3—C3—C5−153.08 (6)
Symmetry codes: (i) −x+1, −y+2, −z+1.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O3—H1O3···O60.951.612.5034 (13)154
N1—H1N1···O5ii0.862.443.169 (2)143
N1—H2N1···O2iii0.862.473.0810 (19)129
N1—H2N1···O1iv0.862.503.3243 (18)161
N2—H1N2···O7v0.862.062.906 (2)169
N2—H2N2···O4iv0.862.072.8811 (14)157
N3—H1N3···O6v0.862.022.860 (2)167
N3—H2N3···O5ii0.862.122.937 (2)157
N4—H1N4···O1Wvi0.862.102.916 (2)157
N4—H2N4···O6vii0.862.563.0760 (18)119
N4—H2N4···O7ii0.862.262.9973 (17)144
N5—H1N5···O2iii0.862.062.8484 (15)152
N5—H2N5···O7ii0.862.032.8273 (17)153
N6—H1N6···O3iv0.862.183.0140 (14)164
N6—H2N6···O40.861.992.8387 (18)170
O1W—H1W1···O4vi0.782.523.032 (2)124
O1W—H2W1···O1iii0.902.032.932 (2)175
Symmetry codes: (ii) −x+1, −y+1, −z; (iii) x, y−1, z; (iv) −x+1, −y+1, −z+1; (v) −x, −y+1, −z; (vi) −x+2, −y+1, −z+1; (vii) x+1, y, z.
Table 1
Selected geometric parameters (Å) top
Cu1—O21.9169 (7)Cu1—O32.2016 (7)
Cu1—O12.0857 (8)
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O3—H1O3···O60.951.612.5034 (13)154
N1—H1N1···O5i0.862.443.169 (2)143
N1—H2N1···O2ii0.862.473.0810 (19)129
N1—H2N1···O1iii0.862.503.3243 (18)161
N2—H1N2···O7iv0.862.062.906 (2)169
N2—H2N2···O4iii0.862.072.8811 (14)157
N3—H1N3···O6iv0.862.022.860 (2)167
N3—H2N3···O5i0.862.122.937 (2)157
N4—H1N4···O1Wv0.862.102.916 (2)157
N4—H2N4···O6vi0.862.563.0760 (18)119
N4—H2N4···O7i0.862.262.9973 (17)144
N5—H1N5···O2ii0.862.062.8484 (15)152
N5—H2N5···O7i0.862.032.8273 (17)153
N6—H1N6···O3iii0.862.183.0140 (14)164
N6—H2N6···O40.861.992.8387 (18)170
O1W—H1W1···O4v0.782.523.032 (2)124
O1W—H2W1···O1ii0.902.032.932 (2)175
Symmetry codes: (i) −x+1, −y+1, −z; (ii) x, y−1, z; (iii) −x+1, −y+1, −z+1; (iv) −x, −y+1, −z; (v) −x+2, −y+1, −z+1; (vi) x+1, y, z.
Acknowledgements top

NM gratefully acknowledges funding from Universiti Sains Malaysia (USM) under the University Research Grant (No. 1001/PFARMASI/815025). HKF thanks USM for the Research University Golden Goose Grant (No. 1001/PFIZIK/811012). CSY thanks USM for the award of a USM Fellowship.

references
References top

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