Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536800021140/ob6012sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536800021140/ob6012Isup2.hkl |
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (Au-Br) = 0.002 Å
- R factor = 0.049
- wR factor = 0.097
- Data-to-parameter ratio = 25.3
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry PLATON alerts of the form PLAT_7?? have been detected for an inorganic structure. These tests are under development for inorganics and comments are welcomed. It is not necessary to supply a data validation response form for these alerts at this time.
Alert Level B:
CHEMS_01 Alert B The sum formula contains elements in the wrong order. H precedes Au Sequence must be C, H, then alphabetical. PLAT_722 Alert B Angle Calc 129.58, Rep 127.00, Dev. 2.58 Degree NA -O -H1 5.656 1.555 1.555
Alert Level C:
PLAT_722 Alert C Angle Calc 110.82, Rep 112.00, Dev. 1.18 Degree NA -O -H1 1.555 1.555 1.555 PLAT_722 Alert C Angle Calc 82.87, Rep 81.00, Dev. 1.87 Degree NA -O -H2 5.656 1.555 1.555 General Notes
FORMU_01 There is a discrepancy between the atom counts in the _chemical_formula_sum and _chemical_formula_moiety. This is usually due to the moiety formula being in the wrong format. Atom count from _chemical_formula_sum: H4 Au1 Br4 Na1 O2 Atom count from _chemical_formula_moiety:H2 Au1 Br4 Na1 O2
0 Alert Level A = Potentially serious problem
2 Alert Level B = Potential problem
2 Alert Level C = Please check
Crystals were prepared by dissolving powder of NaAuCl4.2H2O in aqueous HBr (1 M). The solution was slowly evaporated (two months) at 300 K. After complete crystallization, dark brick red crystals were obtained. A single-crystal was then sealed in Lindemann glass capillary.
In the final electron-density difference map, both minimum (-1.57 e Å-3 at 0.3594, 1/4,0.5494) and maximum (2.09 e Å-3 at 0.4964,0.1831,0.2760) occur respectively at 0.96 Å away from Br4 and 1.72 Å from Na. They may be due to the irregular crystal shape and the approximate absorption correction. The H atoms were fixed with O—H distances of 0.95 Å.
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CADAK and SORTAV (Blessing, 1987); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 1985); software used to prepare material for publication: SHELXL97.
NaAuBr4·2H2O | Dx = 4.201 Mg m−3 |
Mr = 575.63 | Ag Kα radiation, λ = 0.5608 Å |
Orthorhombic, Pnma | Cell parameters from 25 reflections |
a = 13.320 (6) Å | θ = 8.3–10.4° |
b = 7.253 (2) Å | µ = 18.20 mm−1 |
c = 9.420 (3) Å | T = 293 K |
V = 910.1 (6) Å3 | Parallelepiped, dark red |
Z = 4 | 0.16 × 0.09 × 0.06 mm |
F(000) = 1000 |
Enraf Nonius CAD-4 diffractometer | 905 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.000 |
Graphite monochromator | θmax = 22.9°, θmin = 2.1° |
ω–2θ scans | h = 0→18 |
Absorption correction: ψ scan (SORTAV; Blessing, 1987) | k = 0→10 |
Tmin = 0.051, Tmax = 0.363 | l = 0→13 |
1368 measured reflections | 2 standard reflections every 180 min |
1368 independent reflections | intensity decay: 0.1% |
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)] = 0.049 | H-atom parameters constrained |
wR(F2) = 0.097 | w = 1/[σ2(Fo2) + (0.0178P)2 + 12.749P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max < 0.001 |
1368 reflections | Δρmax = 2.09 e Å−3 |
54 parameters | Δρmin = −1.57 e Å−3 |
3 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0047 (3) |
NaAuBr4·2H2O | V = 910.1 (6) Å3 |
Mr = 575.63 | Z = 4 |
Orthorhombic, Pnma | Ag Kα radiation, λ = 0.5608 Å |
a = 13.320 (6) Å | µ = 18.20 mm−1 |
b = 7.253 (2) Å | T = 293 K |
c = 9.420 (3) Å | 0.16 × 0.09 × 0.06 mm |
Enraf Nonius CAD-4 diffractometer | 905 reflections with I > 2σ(I) |
Absorption correction: ψ scan (SORTAV; Blessing, 1987) | Rint = 0.000 |
Tmin = 0.051, Tmax = 0.363 | 2 standard reflections every 180 min |
1368 measured reflections | intensity decay: 0.1% |
1368 independent reflections |
R[F2 > 2σ(F2)] = 0.049 | 3 restraints |
wR(F2) = 0.097 | H-atom parameters constrained |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0178P)2 + 12.749P] where P = (Fo2 + 2Fc2)/3 |
1368 reflections | Δρmax = 2.09 e Å−3 |
54 parameters | Δρmin = −1.57 e Å−3 |
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 | ||
Au | 0.43636 (5) | 0.2500 | 0.01537 (7) | 0.0258 (2) | |
Br1 | 0.32724 (15) | 0.2500 | −0.1914 (2) | 0.0422 (5) | |
Br2 | 0.28961 (13) | 0.2500 | 0.16910 (19) | 0.0364 (5) | |
Br3 | 0.58537 (14) | 0.2500 | −0.1329 (2) | 0.0411 (5) | |
Br4 | 0.54477 (15) | 0.2500 | 0.2209 (2) | 0.0462 (6) | |
Na | 0.4885 (6) | 0.2500 | 0.5620 (10) | 0.051 (2) | |
O | 0.3845 (7) | 0.0025 (16) | 0.4674 (10) | 0.050 (3) | |
H1 | 0.321 | 0.00 | 0.513 | 0.08* | |
H2 | 0.373 | −0.02 | 0.370 | 0.08* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Au | 0.0209 (3) | 0.0288 (3) | 0.0276 (3) | 0.000 | 0.0002 (3) | 0.000 |
Br1 | 0.0319 (10) | 0.0647 (15) | 0.0298 (9) | 0.000 | −0.0044 (8) | 0.000 |
Br2 | 0.0236 (8) | 0.0534 (13) | 0.0321 (9) | 0.000 | 0.0017 (7) | 0.000 |
Br3 | 0.0299 (10) | 0.0523 (12) | 0.0410 (11) | 0.000 | 0.0107 (8) | 0.000 |
Br4 | 0.0309 (11) | 0.0710 (15) | 0.0367 (11) | 0.000 | −0.0099 (8) | 0.000 |
Na | 0.046 (5) | 0.053 (5) | 0.054 (5) | 0.000 | −0.001 (4) | 0.000 |
O | 0.043 (5) | 0.072 (8) | 0.033 (5) | −0.013 (6) | −0.003 (4) | −0.001 (6) |
Au—Br4 | 2.415 (2) | Na—Oiii | 2.509 (13) |
Au—Br3 | 2.427 (2) | Na—Oiv | 2.509 (13) |
Au—Br1 | 2.431 (2) | Na—Br3v | 3.150 (10) |
Au—Br2 | 2.433 (2) | Na—Br1v | 3.163 (9) |
Br1—Nai | 3.163 (9) | Na—Naiv | 3.823 (6) |
Br3—Nai | 3.150 (10) | Na—Navi | 3.823 (6) |
Br4—Na | 3.300 (10) | O—Naiv | 2.509 (13) |
Na—O | 2.437 (12) | O—H1 | 0.95 |
Na—Oii | 2.437 (12) | O—H2 | 0.95 |
Br4—Au—Br3 | 88.41 (8) | Oiii—Na—Br4 | 74.9 (3) |
Br4—Au—Br1 | 180.00 (8) | Oiv—Na—Br4 | 74.9 (3) |
Br3—Au—Br1 | 91.59 (8) | Br3v—Na—Br4 | 142.7 (3) |
Br4—Au—Br2 | 90.19 (8) | Br1v—Na—Br4 | 150.4 (3) |
Br3—Au—Br2 | 178.60 (7) | O—Na—Naiv | 40.1 (3) |
Br1—Au—Br2 | 89.81 (8) | Oii—Na—Naiv | 129.3 (5) |
Au—Br1—Nai | 100.51 (18) | Oiii—Na—Naiv | 127.2 (5) |
Au—Br3—Nai | 100.95 (17) | Oiv—Na—Naiv | 38.7 (3) |
Au—Br4—Na | 130.15 (17) | Br3v—Na—Naiv | 104.2 (3) |
O—Na—Oii | 94.9 (6) | Br1v—Na—Naiv | 106.2 (3) |
O—Na—Oiii | 151.7 (4) | Br4—Na—Naiv | 71.6 (3) |
Oii—Na—Oiii | 78.8 (4) | O—Na—Navi | 129.3 (5) |
O—Na—Oiv | 78.8 (4) | Oii—Na—Navi | 40.1 (3) |
Oii—Na—Oiv | 151.7 (4) | Oiii—Na—Navi | 38.7 (3) |
Oiii—Na—Oiv | 93.8 (5) | Oiv—Na—Navi | 127.2 (5) |
O—Na—Br3v | 124.5 (3) | Br3v—Na—Navi | 104.2 (3) |
Oii—Na—Br3v | 124.5 (3) | Br1v—Na—Navi | 106.2 (3) |
Oiii—Na—Br3v | 79.9 (3) | Br4—Na—Navi | 71.6 (3) |
Oiv—Na—Br3v | 79.9 (3) | Naiv—Na—Navi | 143.1 (5) |
O—Na—Br1v | 83.3 (3) | Na—O—Naiv | 101.2 (4) |
Oii—Na—Br1v | 83.3 (3) | Na—O—H1 | 112 |
Oiii—Na—Br1v | 122.6 (3) | Naiv—O—H1 | 127 |
Oiv—Na—Br1v | 122.6 (3) | Na—O—H2 | 126 |
Br3v—Na—Br1v | 67.0 (2) | Naiv—O—H2 | 81 |
O—Na—Br4 | 76.9 (3) | H1—O—H2 | 107 |
Oii—Na—Br4 | 76.9 (3) |
Symmetry codes: (i) x, y, z−1; (ii) x, −y+1/2, z; (iii) −x+1, y+1/2, −z+1; (iv) −x+1, −y, −z+1; (v) x, y, z+1; (vi) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | NaAuBr4·2H2O |
Mr | 575.63 |
Crystal system, space group | Orthorhombic, Pnma |
Temperature (K) | 293 |
a, b, c (Å) | 13.320 (6), 7.253 (2), 9.420 (3) |
V (Å3) | 910.1 (6) |
Z | 4 |
Radiation type | Ag Kα, λ = 0.5608 Å |
µ (mm−1) | 18.20 |
Crystal size (mm) | 0.16 × 0.09 × 0.06 |
Data collection | |
Diffractometer | Enraf Nonius CAD-4 diffractometer |
Absorption correction | ψ scan (SORTAV; Blessing, 1987) |
Tmin, Tmax | 0.051, 0.363 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1368, 1368, 905 |
Rint | 0.000 |
(sin θ/λ)max (Å−1) | 0.694 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.097, 1.09 |
No. of reflections | 1368 |
No. of parameters | 54 |
No. of restraints | 3 |
H-atom treatment | H-atom parameters constrained |
w = 1/[σ2(Fo2) + (0.0178P)2 + 12.749P] where P = (Fo2 + 2Fc2)/3 | |
Δρmax, Δρmin (e Å−3) | 2.09, −1.57 |
Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, CADAK and SORTAV (Blessing, 1987), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ATOMS (Dowty, 1985), SHELXL97.
Au—Br4 | 2.415 (2) | Br4—Na | 3.300 (10) |
Au—Br3 | 2.427 (2) | Na—O | 2.437 (12) |
Au—Br1 | 2.431 (2) | Na—Oii | 2.437 (12) |
Au—Br2 | 2.433 (2) | Na—Oiii | 2.509 (13) |
Br1—Nai | 3.163 (9) | Na—Oiv | 2.509 (13) |
Br3—Nai | 3.150 (10) | ||
Br4—Au—Br3 | 88.41 (8) | Br4—Au—Br2 | 90.19 (8) |
Br4—Au—Br1 | 180.00 (8) | Br3—Au—Br2 | 178.60 (7) |
Br3—Au—Br1 | 91.59 (8) | Br1—Au—Br2 | 89.81 (8) |
Symmetry codes: (i) x, y, z−1; (ii) x, −y+1/2, z; (iii) −x+1, y+1/2, −z+1; (iv) −x+1, −y, −z+1. |
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Previous studies concerning the crystal structure determination of the anhydrous MAuX4 compounds and the corresponding dihydrate MAuX4.2H2O (M is Na or K, X is Cl or Br) have shown that: (i) KAuBr4 (Omrani et al., 1999), KAuBr4.2H2O (Omrani et al., 1986), KAuCl4 (Jones & Bembenek, 1992) and NaAuCl4 (Jones et al., 1988) crystallize in the monoclinic system with the space group P21/c (or P21/n); (ii) NaAuCl4.2H2O (Bonamico & Dessy, 1965) and KAuCl4.2H2O (Theobald & Omrani, 1980) crystallize in the orthorhombic system with the space group Pnma and Pbcn, respectively. All these compounds are characterized by the occurrence of square-planar AuX4- anions with typical Au—X distances (approximately 2.29 Å for Au—Cl bond and 2.43 Å for Au—Br bond). In this class of based gold coordination compounds, only both NaAuBr4 and NaAuBr4.2H2O compounds were not yet characterized. In the present work, we report on the crystal structure of the dihydrate.
The structure of the title compound, NaAuBr4.2H2O, (I), is isomorphous with that of NaAuCl4.2H2O (Bonamico & Dessy, 1965). The orthorhombic cell contains four Au atoms and the AuBr4- anions are nearly square planar (Fig. 1). The Au, Br and Na atoms lie on the mirror plane. The structure can also be described as a pseudo-lamellar compound in which the NaAuBr4 planes (at y = 1/4 and 3/4) are piled up along the b axis and connected via Na—O—Na bonds. There is only one independent Na atom, which is coordinated by four O atoms at distances in the range 2.437 (12)–2.509 (13) Å and three Br atoms at distances in the range 3.150 (10)–3.300 (10) Å (Table 1).