Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S2052520614018563/bp5071sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S2052520614018563/bp5071Isup2.hkl |
CCDC reference: 1016070
The new HAuCl4·0.65C2H5OH·1.35H2O compound was crystallized from anhydrous ethanol by dissolving HAuCl4·3H2O and slow evaporation in argon atmosphere. HAuCl4·3H2O was obtained by dissolving gold in aqua regia at 80 °C. HNO3 was removed from the solution by repeated evaporation, while adding more HCl. After the final evaporation of HCl and subsequent coagulation by cooling, crystalline material of HAuCl4·3H2O was obtained.
A yellow single crystal of HAuCl4·0.65C2H5OH·1.35H2O was sealed in a capillary for intensity measurements using an X-ray single crystal diffractometer (Stoe, IPDS, Darmstadt, Germany), equipped with (graphite) monochromated Mo-Kα radiation (λ = 71.073 pm). The intensity data were corrected for Lorentz factors, polarization effects by the IPDS software. Crystal structure solutions were performed with direct methods (SHELXS), followed by full matrix least square structure refinements (SHELXL-97) (Sheldrick, 1997). The hydrogen atoms of the hydronium ion were calculated geometrically and refined using AFIX 1. Further details of the crystal structure investigation may be obtained free of charge via https://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit @ccdc.cam.ac.uk, on quoting the depository number CCDC 1016070. ATR-FTIR measurement was carried on a Perkin–Elmer FTIR spectrometer (Spectrum 1000).
The new HAuCl4·0.65C2H5OH·1.35H2O compound was crystallized from anhydrous ethanol by dissolving HAuCl4·3H2O and slow evaporation in argon atmosphere
Crystal data, data collection and structure refinement details are summarized in Table 1.
The tetrahydrate and trihydrate of tetrachloroauric acid are commercially available and commonly used as starting material in the synthesis of gold complexes and gold nanoparticles. A yellow cubic-shaped single crystal of HAuCl4·0.65C2H5OH·1.35H2O was chosen for X-ray single crystal structure determination. Atomic coordinates and isotropic equivalent displacement parameters are reported in Table 1. A summary of selected bond lengths is listed in Table 2. HAuCl4·0.65C2H5OH·1.35H2O crystallizes with two formula units in the triclinic system with the space group P (no. 2) with a = 804.5 (2), b = 804.6 (2), c = 1029.1 (2) pm, and α = 94.31 (3)°, β = 104.08 (2)°, γ = 109.21 (3)°.
The crystal structure presented in Figure 1 contains gold atoms surrounded by four chlorine atoms. The [AuCl4]- ion in the structure has approximately square-planar geometry (Bonamico & Dessy, 1973) with a maximum deviation less than 2 pm (Tab. 2). [AuCl4]- units are arranged in chains parallel to the crystallographic b-axis direction. Ethanol and water molecules occupy spaces in-between the chains. The oxygen atoms from ethanol and water molecules share the same lattice site in the crystal structure of HAuCl4·0.65C2H5OH·1.35H2O. The Au–Au contacts within chains are 405.8 (2) and 631.6 (2) pm and can be regarded as nonbonding (Wells, 1971; Mingos, 1996; Mendizabal & Pyykkö, 2004). The shorter distance is comparable with [NH(C2H4OH)3]+[AuCl4]–·H2O, where Au–Au contacts are about 409 and 425 pm (Sharutin et al., 2010). The chain structure of the gold(III) complexes where the [AuCl4]- ions are stabilized by different ligands present for example in [EtC(OEt)NH2]+[AuCl4]- (Potts et al., 1991), [NH(C2H4OH)3]+[AuCl4]-·H2O (Sharutin et al., 2010) or [C4H12N2]2+[AuCl4]22-·2H2O (Polishchuk et al., 2009).
The cohesion in the structure between [AuCl4]- ions and protonated water with ethanol molecules is given by a network of hydrogen bridges. Nearest neighbor Cl???O distances are 330.1 (1) pm for Cl(1), 327.7 (1) pm for Cl(2), 322.9 (1) for Cl(3), and 316.9 (1) pm for Cl(4). The values are similar to the closest distance between non-hydrogen atoms in [NH(C2H4OH)3]+[AuCl4]-·H2O where Cl???O distance is about 326 pm for water molecule (O???O distances between water and different ammonium cations are about 280 pm) (Sharutin et al., 2010) and in [EtC(OEt)NH2]+[AuCl4]- where Cl???N distance is 335 pm (Potts et al., 1991). Nuclear quadrupole resonance studies performed for NaAuCl4·2H2O and NaAuCl4·2D2O suggest that chlorine atoms form two weak hydrogen bonds (Needham, 2013) with two adjacent water molecules at O···Cl(1) distances of approximately 336 pm (Fryer & Smith, 1968).
A closer inspection of the refined crystal structure of HAuCl4·0.65C2H5OH·1.35H2O leads to the conclusion that H+ ions are present in the structure and the formula can be expressed as [(0.65EtOH·1.35H2O)H]+[AuCl4]-. A diaquated proton was described in the structure of the tetrahydrated acid (O?Reilly et al., 1971). From theoretical calculations the minimum energy of the O···O distance of a protonated (H5O2)+ ion was found to be 238 pm (O?Reilly et al., 1971), and thus shorter than in the water dimer (H2O)2 (298 pm) (Buckingham et al., 2008). For HAuCl4·4H2O this distance is about 248 pm (O?Reilly et al., 1971), in HAuCl4·3H2O is 246 pm, and in HAuCl4·2H2O is 238 pm (Büchner & Wickleder, 2005). For the new HAuCl4·0.65C2H5OH·1.35H2O compound the O···O distance is 240.67 (7) pm. The differences in distances for the chloroauric acid hydrates are proportional to the hydrogen bonds of the next water molecules connected to the (H5O2)+ ion, for the new compound the same as for HAuCl4·2H2O there are no chains of water molecules present in the structure. For comparison, in (H5O2)[Au(NO3)4]·H2O where [Au(NO3]4]- units are linked by (H5O2)+ ions the corresponding distance is 243 pm (Büchner & Wickleder, 2004).
The chain structure of HAuCl4·0.65C2H5OH·1.35H2O can also be stabilized by weak C–H···Cl hydrogen bonds (Aullon et al., 1998; Bourosh et al., 2007) with the distances C(1)–Cl(4) 347.9 (1), C(3)–Cl(1) 359.2 (1), and C(4)–Cl(3) 369.0 (1)pm.
The infrared spectrum of HAuCl4·0.65C2H5OH·1.35H2O was recorded in the range of 400-4000 cm-1. The broad absorption band in the 400-3655 cm-1 region can be assigned to the vibration of O–H···O groups (Vol?pin, 1981; Varnek et al., 2002). The spectrum was additionally characterized by sharp bands in the range from 400 to 1865 cm-1, with the three most intensive peaks at 774, 922 and 1502 cm-1. The band for ethanol ascribed to CH3 asymmetric stretching vibration was at 2976 cm-1, the band related to the stretching vibration of the O–H bond was observed at 3297 cm-1. The band at lower energies associated to the stretch vibration of C–O bond in ethanol molecule was difficult to distinguish.
The infrared spectrum of HAuCl4·3H2O was also recorded for comparison. The broad absorption band in the 400-3668 cm-1 region confirmed the presence of the (H5O2)+ ion in the crystal structure and was assigned to the vibration of O–H···O groups (Vol?pin, 1981; Varnek et al., 2002). The band, related to the stretching vibration of the O–H bond for the water molecules, was observed at 3424-3504 cm-1. The broad band between 1358 and 1921 cm-1 with two maximums at 1604 and 1700 cm-1 was assigned to the HOH bending vibrations for the water molecules and one of O–H···O bending vibrations in the (H5O2)+ ions. The asymmetric stretching vibrations and another bending motions of the O–H···O fragment were ascribed to the broad band at 1077 cm-1 (Vener et al., 2001; Vener & Sauer, 2005; Stoyanov & Reed, 2006). At low frequency, band between 400 and 807 with maximum at 492 cm-1, was due to the wagging and rocking modes of the terminal water molecules (Vener & Sauer, 2005; Vendrell et al., 2007).
Data collection: STOE IPDS-Software; cell refinement: STOE IPDS-Software; data reduction: STOE IPDS-Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).
C1.29H7.59AuCl4O2 | Z = 2 |
Mr = 393.97 | F(000) = 357 |
Triclinic, P1 | Dx = 2.176 Mg m−3 |
a = 8.0454 (18) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 8.0457 (18) Å | Cell parameters from 6932 reflections |
c = 10.291 (2) Å | θ = 2.7–25.0° |
α = 94.31 (3)° | µ = 13.07 mm−1 |
β = 104.08 (3)° | T = 235 K |
γ = 109.21 (3)° | Bloc, yellow |
V = 601.3 (2) Å3 | 0.5 × 0.5 × 0.3 mm |
STOE IPDS I diffractometer | 1986 independent reflections |
Radiation source: fine-focus sealed tube | 1719 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.078 |
Oscillation scans | θmax = 25.0°, θmin = 2.7° |
Absorption correction: numerical STOE X-RED/X-SHAPE | h = −9→9 |
Tmin = 0.058, Tmax = 0.123 | k = −9→9 |
6932 measured reflections | l = −12→12 |
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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.087 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.99 | w = 1/[σ2(Fo2) + (0.0529P)2] where P = (Fo2 + 2Fc2)/3 |
1986 reflections | (Δ/σ)max < 0.001 |
101 parameters | Δρmax = 1.10 e Å−3 |
24 restraints | Δρmin = −1.16 e Å−3 |
C1.29H7.59AuCl4O2 | γ = 109.21 (3)° |
Mr = 393.97 | V = 601.3 (2) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.0454 (18) Å | Mo Kα radiation |
b = 8.0457 (18) Å | µ = 13.07 mm−1 |
c = 10.291 (2) Å | T = 235 K |
α = 94.31 (3)° | 0.5 × 0.5 × 0.3 mm |
β = 104.08 (3)° |
STOE IPDS I diffractometer | 1986 independent reflections |
Absorption correction: numerical STOE X-RED/X-SHAPE | 1719 reflections with I > 2σ(I) |
Tmin = 0.058, Tmax = 0.123 | Rint = 0.078 |
6932 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 24 restraints |
wR(F2) = 0.087 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.99 | Δρmax = 1.10 e Å−3 |
1986 reflections | Δρmin = −1.16 e Å−3 |
101 parameters |
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 | Occ. (<1) | |
Au1 | 0.07963 (4) | 0.70101 (4) | 0.15911 (2) | 0.05237 (15) | |
Cl1 | −0.1837 (4) | 0.7499 (4) | 0.1545 (2) | 0.0731 (6) | |
Cl2 | 0.3459 (4) | 0.6563 (4) | 0.1649 (2) | 0.0713 (6) | |
Cl3 | 0.0733 (4) | 0.7847 (3) | −0.04779 (19) | 0.0698 (6) | |
Cl4 | 0.0874 (4) | 0.6162 (4) | 0.3669 (2) | 0.0769 (7) | |
O1 | 0.2993 (10) | 0.3478 (8) | 0.3579 (5) | 0.0722 (18) | |
H5A | 0.4366 | 0.4447 | 0.4088 | 0.087* | 0.68 |
H5B | 0.2383 | 0.4367 | 0.3088 | 0.087* | |
H5C | 0.3321 | 0.2737 | 0.2821 | 0.087* | |
C1 | 0.181 (4) | 0.232 (4) | 0.426 (3) | 0.068 (8) | 0.324 (13) |
H1A | 0.0630 | 0.1611 | 0.3599 | 0.081* | 0.324 (13) |
H1B | 0.1593 | 0.3034 | 0.4963 | 0.081* | 0.324 (13) |
C2 | 0.272 (3) | 0.112 (2) | 0.487 (2) | 0.044 (5) | 0.324 (13) |
H2A | 0.3906 | 0.1834 | 0.5499 | 0.053* | 0.324 (13) |
H2B | 0.2889 | 0.0385 | 0.4160 | 0.053* | 0.324 (13) |
H2C | 0.1960 | 0.0367 | 0.5353 | 0.053* | 0.324 (13) |
O2 | 0.3273 (9) | 0.1898 (9) | 0.1611 (6) | 0.0706 (17) | |
H6A | 0.2027 | 0.1619 | 0.0770 | 0.085* | |
H6B | 0.2907 | 0.0650 | 0.1593 | 0.085* | 0.676 (13) |
C3 | 0.512 (2) | 0.233 (2) | 0.1464 (16) | 0.025 (4) | 0.324 (13) |
H3A | 0.5096 | 0.1565 | 0.0668 | 0.031* | 0.324 (13) |
H3B | 0.5610 | 0.3580 | 0.1343 | 0.031* | 0.324 (13) |
C4 | 0.623 (3) | 0.205 (3) | 0.267 (2) | 0.040 (5) | 0.324 (13) |
H4C | 0.7461 | 0.2278 | 0.2585 | 0.049* | 0.324 (13) |
H4B | 0.5706 | 0.0825 | 0.2797 | 0.049* | 0.324 (13) |
H4A | 0.6292 | 0.2856 | 0.3442 | 0.049* | 0.324 (13) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Au1 | 0.0621 (3) | 0.05993 (18) | 0.03438 (18) | 0.02198 (16) | 0.01269 (14) | 0.00686 (13) |
Cl1 | 0.0721 (16) | 0.1048 (16) | 0.0585 (12) | 0.0469 (14) | 0.0221 (11) | 0.0278 (12) |
Cl2 | 0.0686 (15) | 0.0937 (16) | 0.0646 (13) | 0.0377 (13) | 0.0258 (11) | 0.0272 (12) |
Cl3 | 0.0763 (15) | 0.0981 (15) | 0.0360 (9) | 0.0299 (13) | 0.0152 (9) | 0.0257 (10) |
Cl4 | 0.111 (2) | 0.1089 (17) | 0.0346 (9) | 0.0596 (16) | 0.0291 (10) | 0.0305 (10) |
O1 | 0.107 (5) | 0.092 (4) | 0.034 (3) | 0.049 (4) | 0.024 (3) | 0.034 (3) |
C1 | 0.071 (11) | 0.073 (11) | 0.070 (11) | 0.033 (8) | 0.031 (8) | 0.007 (8) |
C2 | 0.054 (10) | 0.036 (7) | 0.046 (8) | 0.011 (6) | 0.020 (7) | 0.037 (6) |
O2 | 0.065 (4) | 0.093 (4) | 0.051 (3) | 0.030 (4) | 0.009 (3) | 0.016 (3) |
C3 | 0.028 (8) | 0.029 (6) | 0.028 (7) | 0.016 (5) | 0.026 (6) | 0.014 (5) |
C4 | 0.026 (8) | 0.056 (8) | 0.045 (8) | 0.012 (7) | 0.021 (6) | 0.018 (7) |
Au1—Cl1 | 2.268 (3) | O1—C1 | 1.45 (3) |
Au1—Cl2 | 2.274 (3) | C1—C2 | 1.48 (3) |
Au1—Cl3 | 2.2749 (19) | O2—C3 | 1.458 (18) |
Au1—Cl4 | 2.286 (2) | C3—C4 | 1.42 (3) |
Cl1—Au1—Cl2 | 179.18 (9) | Cl2—Au1—Cl4 | 90.67 (9) |
Cl1—Au1—Cl3 | 90.92 (9) | Cl3—Au1—Cl4 | 179.64 (9) |
Cl2—Au1—Cl3 | 88.98 (9) | O1—C1—C2 | 109 (2) |
Cl1—Au1—Cl4 | 89.43 (10) | C4—C3—O2 | 107.4 (12) |
Experimental details
Crystal data | |
Chemical formula | C1.29H7.59AuCl4O2 |
Mr | 393.97 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 235 |
a, b, c (Å) | 8.0454 (18), 8.0457 (18), 10.291 (2) |
α, β, γ (°) | 94.31 (3), 104.08 (3), 109.21 (3) |
V (Å3) | 601.3 (2) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 13.07 |
Crystal size (mm) | 0.5 × 0.5 × 0.3 |
Data collection | |
Diffractometer | STOE IPDS I diffractometer |
Absorption correction | Numerical STOE X-RED/X-SHAPE |
Tmin, Tmax | 0.058, 0.123 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6932, 1986, 1719 |
Rint | 0.078 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.087, 0.99 |
No. of reflections | 1986 |
No. of parameters | 101 |
No. of restraints | 24 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 1.10, −1.16 |
Computer programs: STOE IPDS-Software, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997).