Acta Cryst. (2009). E65, m1377 [ doi:10.1107/S1600536809041063 ]
In the title compound, (C4H12N2)[AuCl4]2·2H2O, the AuIII atom has a square-planar geometry. The piperazinium dication lies on an inversion centre and adopts a typical chair conformation. In the crystal, a combination of N-H
O, N-HCl and O-HCl hydrogen bonds results in the formation of a three-dimensional network.
The chemicals used were of reagent grade. Ciprofloxacin hydrochloride (37 mg, 0.1 mmol) and gold(III) chloride (AuCl3 30 mg, 0.1 mmol) were dissolved in 10 ml of 32% of HCl. Yellow crystals of the title compound, suitable for X-ray analysis, were obtained by slow evaporation in air at rt, after a few days.
The water H-atoms were located from difference electron-density maps and were refined with distance restraints of O—H = 0.85 (2) Å and Uiso(H) = 1.5Ueq(O). All the other H-atoms were positioned geometrically and allowed to ride on their parent atoms: N—H = 0.90 Å, C—H = 0.97 Å with Uiso(H)= 1.2Ueq(parent N or C atom).
Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip, 2009).
![[Figure 1]](./su2149fig1thm.gif)
| Fig. 1. The asymmetric unit of the title compound, showing 50% displacement ellipsoids (arbitrary spheres for the H atoms). |
![[Figure 2]](./su2149fig2thm.gif)
| Fig. 2. Fragment of the water-piperazinium hydrogen bonded chain, with the hydrogen bonds indicated by dotted lines. Symmetry codes are the same as in Table 1. |
![[Figure 3]](./su2149fig3thm.gif)
| Fig. 3. A view along the a axis of the crystal packing of the title compound, with the hydrogen bonds shown as dotted lines. All the C-bound H atoms have been omitted for clarity. Symmetry codes are the same as in Table 1. |
| (C4H12N2)[AuCl4]2·2H2O | F(000) = 728 |
| Mr = 801.72 | Dx = 2.970 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 1008 reflections |
| a = 7.7327 (11) Å | θ = 3.4–30.6° |
| b = 10.1114 (15) Å | µ = 17.53 mm−1 |
| c = 11.9024 (18) Å | T = 296 K |
| β = 105.565 (3)° | Prism, yellow |
| V = 896.5 (2) Å3 | 0.33 × 0.23 × 0.08 mm |
| Z = 2 |
| Bruker SMART CCD 1000 diffractometer | 2630 independent reflections |
| Radiation source: fine-focus sealed tube | 2446 reflections with I > 2σ(I) |
| graphite | Rint = 0.018 |
| Detector resolution: 8.33 pixels mm-1 | θmax = 31.5°, θmin = 2.7° |
| ω scans | h = −10→9 |
| Absorption correction: gaussian (XPREP and SADABS; Bruker, 2003) | k = −13→12 |
| Tmin = 0.043, Tmax = 0.251 | l = −14→17 |
| 6689 measured reflections |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.018 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.044 | w = 1/[σ2(Fo2) + (0.0203P)2 + 0.7643P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.09 | (Δ/σ)max = 0.002 |
| 2630 reflections | Δρmax = 1.36 e Å−3 |
| 89 parameters | Δρmin = −0.75 e Å−3 |
| 2 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.01512 (17) |
| (C4H12N2)[AuCl4]2·2H2O | V = 896.5 (2) Å3 |
| Mr = 801.72 | Z = 2 |
| Monoclinic, P21/c | Mo Kα radiation |
| a = 7.7327 (11) Å | µ = 17.53 mm−1 |
| b = 10.1114 (15) Å | T = 296 K |
| c = 11.9024 (18) Å | 0.33 × 0.23 × 0.08 mm |
| β = 105.565 (3)° |
| Bruker SMART CCD 1000 diffractometer | 2630 independent reflections |
| Absorption correction: gaussian (XPREP and SADABS; Bruker, 2003) | 2446 reflections with I > 2σ(I) |
| Tmin = 0.043, Tmax = 0.251 | Rint = 0.018 |
| 6689 measured reflections | θmax = 31.5° |
| R[F2 > 2σ(F2)] = 0.018 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.044 | Δρmax = 1.36 e Å−3 |
| S = 1.09 | Δρmin = −0.75 e Å−3 |
| 2630 reflections | Absolute structure: ? |
| 89 parameters | Flack parameter: ? |
| 2 restraints | Rogers parameter: ? |
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. |
| x | y | z | Uiso*/Ueq | ||
| Au1 | 0.258077 (10) | 0.481141 (8) | 0.040268 (7) | 0.03248 (2) | |
| Cl1 | 0.22668 (9) | 0.31457 (6) | 0.16243 (5) | 0.04886 (14) | |
| Cl2 | 0.12348 (9) | 0.34990 (6) | −0.11438 (5) | 0.04885 (15) | |
| Cl3 | 0.29217 (10) | 0.64504 (6) | −0.08394 (6) | 0.05264 (16) | |
| Cl4 | 0.39054 (10) | 0.60981 (7) | 0.19756 (6) | 0.05297 (16) | |
| O1 | 0.5108 (2) | 0.88550 (19) | 0.07637 (17) | 0.0495 (4) | |
| H1 | 0.499 (5) | 0.8047 (14) | 0.075 (3) | 0.074* | |
| H2 | 0.546 (5) | 0.890 (4) | 0.1494 (12) | 0.074* | |
| N1 | 0.1859 (2) | 0.02747 (18) | 0.01336 (18) | 0.0360 (4) | |
| H1A | 0.1882 | 0.1163 | 0.0188 | 0.043* | |
| H1B | 0.2985 | −0.0004 | 0.0190 | 0.043* | |
| C2 | 0.1246 (3) | −0.0285 (2) | 0.1115 (2) | 0.0390 (5) | |
| H2A | 0.2018 | 0.0029 | 0.1849 | 0.047* | |
| H2B | 0.1330 | −0.1242 | 0.1106 | 0.047* | |
| C3 | −0.0679 (3) | 0.0117 (2) | 0.1018 (2) | 0.0384 (5) | |
| H3A | −0.1087 | −0.0305 | 0.1632 | 0.046* | |
| H3B | −0.0741 | 0.1067 | 0.1113 | 0.046* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Au1 | 0.03239 (3) | 0.02880 (4) | 0.03751 (4) | 0.00020 (3) | 0.01157 (3) | −0.00039 (3) |
| Cl1 | 0.0685 (3) | 0.0368 (3) | 0.0414 (3) | −0.0146 (2) | 0.0150 (2) | 0.0013 (2) |
| Cl2 | 0.0623 (3) | 0.0419 (3) | 0.0398 (3) | −0.0061 (3) | 0.0092 (2) | −0.0053 (2) |
| Cl3 | 0.0701 (4) | 0.0397 (3) | 0.0488 (3) | −0.0048 (3) | 0.0172 (3) | 0.0087 (2) |
| Cl4 | 0.0677 (3) | 0.0412 (3) | 0.0463 (3) | −0.0155 (3) | 0.0088 (3) | −0.0056 (2) |
| O1 | 0.0402 (7) | 0.0474 (9) | 0.0594 (10) | 0.0011 (7) | 0.0107 (7) | 0.0196 (8) |
| N1 | 0.0297 (7) | 0.0361 (9) | 0.0450 (9) | −0.0024 (6) | 0.0151 (7) | −0.0022 (7) |
| C2 | 0.0357 (9) | 0.0425 (12) | 0.0386 (11) | 0.0013 (8) | 0.0096 (8) | 0.0047 (8) |
| C3 | 0.0371 (9) | 0.0442 (11) | 0.0382 (10) | −0.0045 (8) | 0.0176 (8) | −0.0048 (8) |
| Au1—Cl1 | 2.2802 (6) | N1—H1A | 0.9000 |
| Au1—Cl2 | 2.2813 (6) | N1—H1B | 0.9000 |
| Au1—Cl3 | 2.2827 (7) | C2—C3 | 1.517 (3) |
| Au1—Cl4 | 2.2842 (7) | C2—H2A | 0.9700 |
| O1—H1 | 0.822 (14) | C2—H2B | 0.9700 |
| O1—H2 | 0.839 (13) | C3—H3A | 0.9700 |
| N1—C3i | 1.482 (3) | C3—H3B | 0.9700 |
| N1—C2 | 1.486 (3) | ||
| Cl1—Au1—Cl2 | 88.92 (3) | N1—C2—C3 | 110.55 (18) |
| Cl1—Au1—Cl3 | 178.87 (3) | N1—C2—H2A | 109.5 |
| Cl2—Au1—Cl3 | 90.39 (3) | C3—C2—H2A | 109.5 |
| Cl1—Au1—Cl4 | 89.95 (3) | N1—C2—H2B | 109.5 |
| Cl2—Au1—Cl4 | 178.82 (2) | C3—C2—H2B | 109.5 |
| Cl3—Au1—Cl4 | 90.74 (3) | H2A—C2—H2B | 108.1 |
| H1—O1—H2 | 94 (3) | N1i—C3—C2 | 110.31 (19) |
| C3i—N1—C2 | 112.20 (17) | N1i—C3—H3A | 109.6 |
| C3i—N1—H1A | 109.2 | C2—C3—H3A | 109.6 |
| C2—N1—H1A | 109.2 | N1i—C3—H3B | 109.6 |
| C3i—N1—H1B | 109.2 | C2—C3—H3B | 109.6 |
| C2—N1—H1B | 109.2 | H3A—C3—H3B | 108.1 |
| H1A—N1—H1B | 107.9 |
| Symmetry codes: (i) −x, −y, −z. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1B···O1ii | 0.90 | 1.97 | 2.815 (3) | 155 |
| N1—H1B···O1iii | 0.90 | 2.39 | 2.960 (3) | 121 |
| O1—H2···Cl1iv | 0.84 (1) | 2.57 (2) | 3.3035 (19) | 147 (3) |
| O1—H2···Cl4iv | 0.84 (1) | 2.83 (3) | 3.445 (2) | 131 (3) |
| O1—H1···Cl4 | 0.82 (1) | 2.71 (3) | 3.382 (2) | 140 (3) |
| O1—H1···Cl3 | 0.82 (1) | 2.67 (3) | 3.268 (2) | 131 (3) |
| N1—H1A···Cl1 | 0.90 | 2.60 | 3.373 (2) | 144 |
| N1—H1A···Cl2 | 0.90 | 2.81 | 3.575 (2) | 143 |
| Symmetry codes: (ii) x, y−1, z; (iii) −x+1, −y+1, −z; (iv) −x+1, y+1/2, −z+1/2. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1B···O1i | 0.90 | 1.97 | 2.815 (3) | 155 |
| N1—H1B···O1ii | 0.90 | 2.39 | 2.960 (3) | 121 |
| O1—H2···Cl1iii | 0.84 (1) | 2.57 (2) | 3.3035 (19) | 147 (3) |
| O1—H2···Cl4iii | 0.84 (1) | 2.83 (3) | 3.445 (2) | 131 (3) |
| O1—H1···Cl4 | 0.82 (1) | 2.71 (3) | 3.382 (2) | 140 (3) |
| O1—H1···Cl3 | 0.82 (1) | 2.67 (3) | 3.268 (2) | 131 (3) |
| N1—H1A···Cl1 | 0.90 | 2.60 | 3.373 (2) | 144 |
| N1—H1A···Cl2 | 0.90 | 2.81 | 3.575 (2) | 143 |
| Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+1, −z; (iii) −x+1, y+1/2, −z+1/2. |
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The asymmetric unit of the title compound consists of a discrete [AuCl4]- complex anion, one water molecule and one-half of a diprotonated piperazinium dication (Fig. 1). The Au atom in the tetrachloridoaurate anion exhibits a square-planar coordination. A similar geometry has been observed, for exemple, in tetraphenylantimony(V) tetrachloroaurate (Sharutin et al., 2008) and bipyridinium tetrachloroaurate (Zhang et al., 2006). The Au—Cl bond lengths are in the range of 2.2802 (6) - 2.2842 (7) Å. In the crystal structure, the anions are stacked into columns along the a axis, parallel to each other. The distances between anion planes are ca. 3.734 and 3.999 Å. The organic piperazinium dication lies at an inversion centre and adopts a typical chair geometry with normal valence bond lengths (Allen et al., 1987) and angles, as observed in the structures of piperazinediium tetrachloridozincate (Sutherland & Harrison, 2009) and piperazinediium tetrachloridozincate monohydrate (Kefi & Nasr, 2005).
The piperazinium dications and water molecules are linked by intermolecular bifurcated N—H···O hydrogen bonds to form chains proagagting along the [100] direction (Fig. 2). The water-piperaziniun chains and the anion stacks form a three-dimensional framework (Fig. 3) via bifurcated N—H···Cl and O—H···Cl hydrogen bonds (Table 1).