Acta Cryst. (2007). E63, i164-i165 [ doi:10.1107/S1600536807029790 ]
The crystal structure of dicaesium hexaaquacopper(II) bis[sulfate(VI)], Cs2[Cu(H2O)6](SO4)2, has been redetermined from single-crystal X-ray diffraction data. In comparison with the previous refinement based on single-crystal neutron data [Shields & Kennard (1972). Cryst. Struct. Commun. 1, 189-191], the results show an improved precision and benefit from inclusion of anisotropic displacement parameters for the non-H atoms. The structure is characterized by a mean Cu-O bond length of 2.094 Å. The [Cu(H2O)6] octahedron (
symmetry) is strongly distorted because of the Jahn-Teller effect, with a calculated distortion parameter ![[Delta]](http://journals.iucr.org/logos/entities/Delta_rmgif.gif)
of 0.0054. The Cs+ cation is ninefold coordinated by seven O atoms and two water molecules, with a mean Cs-O bond length of 3.238 Å.
The title compound has been prepared by dissolving Cs2SO4 (Carlo Erba, P·P·A.) and CuSO4.5H2O (Carlo Erba, P·P·A.) in double deionized water and subsequent slow evaporation of the solvent at 295 K. The obtained crystals, in equilibrium with the mother solution, were removed by filtration and dried at room temperature. The product consisted of platy blue crystals of Cs2[Cu(H2O)6](SO4)2.
The structure was refined in the non-standard setting P21/a of space group P21/c for a better comparison with other Tutton's salts. After a few refinement cycles using neutral scattering factors, fully ionized for Cu and half ionized for O and neutral scattering factors for the remaining atoms were finally selected, leading to the lowest R agreement indices. The coordinates of the hydrogen atoms were refined freely using a common Uiso parameter of 0.05 Å2. The deepest hole and the highest peak are, respectively, 0.69 and 0.75 Å from atom Cs.
Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 2003); software used to prepare material for publication: PARST (Nardelli, 1982) and publCIF (Westrip, 2007).
![[Figure 1]](./wm2127fig1thm.gif)
| Fig. 1. The crystal structure of Cs2[Cu(H2O)6](SO4)2 in polyhedral representation, projected along [001]. |
| Cs2[Cu(H2O)6](SO4)2 | F000 = 613.8 |
| Mr = 629.61 | Non-standard setting of space group P21/c to adhere to reference data of other Tutton's salts |
| Monoclinic, P21/a | Dx = 2.864 Mg m−3 |
| Hall symbol: -P 2yab | Mo Kα radiation λ = 0.71073 Å |
| a = 9.4383 (6) Å | Cell parameters from 58 reflections |
| b = 12.7605 (12) Å | θ = 4.0–22.5º |
| c = 6.3130 (6) Å | µ = 6.76 mm−1 |
| β = 106.199 (7)º | T = 293 (2) K |
| V = 730.14 (11) Å3 | Plate, blue |
| Z = 2 | 0.30 × 0.20 × 0.20 mm |
| Siemens P4 diffractometer | Rint = 0.031 |
| Radiation source: fine-focus sealed tube | θmax = 35.0º |
| Monochromator: graphite | θmin = 2.8º |
| T = 293(2) K | h = −15→14 |
| ω scans | k = 0→20 |
| Absorption correction: ψ scan (North et al., 1968) | l = 0→10 |
| Tmin = 0.226, Tmax = 0.584 | 3 standard reflections |
| 3436 measured reflections | every 47 reflections |
| 3208 independent reflections | intensity decay: 1% |
| 2728 reflections with I > 2σ(I) |
| Refinement on F2 | Only H-atom coordinates refined |
| Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.0466P)2 + 0.5369P] where P = (Fo2 + 2Fc2)/3 |
| R[F2 > 2σ(F2)] = 0.034 | (Δ/σ)max = 0.001 |
| wR(F2) = 0.081 | Δρmax = 1.53 e Å−3 |
| S = 1.09 | Δρmin = −2.57 e Å−3 |
| 3208 reflections | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| 109 parameters | Extinction coefficient: 0.080 (2) |
| Cs2[Cu(H2O)6](SO4)2 | V = 730.14 (11) Å3 |
| Mr = 629.61 | Z = 2 |
| Monoclinic, P21/a | Mo Kα |
| a = 9.4383 (6) Å | µ = 6.76 mm−1 |
| b = 12.7605 (12) Å | T = 293 (2) K |
| c = 6.3130 (6) Å | 0.30 × 0.20 × 0.20 mm |
| β = 106.199 (7)º |
| Siemens P4 diffractometer | 2728 reflections with I > 2σ(I) |
| Absorption correction: ψ scan (North et al., 1968) | Rint = 0.031 |
| Tmin = 0.226, Tmax = 0.584 | 3 standard reflections |
| 3436 measured reflections | every 47 reflections |
| 3208 independent reflections | intensity decay: 1% |
| R[F2 > 2σ(F2)] = 0.034 | 109 parameters |
| wR(F2) = 0.081 | Only H-atom coordinates refined |
| S = 1.09 | Δρmax = 1.53 e Å−3 |
| 3208 reflections | Δρmin = −2.57 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 > 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 | ||
| Cu | 0.0000 | 0.0000 | 0.0000 | 0.01692 (10) | |
| Cs | 0.11407 (2) | 0.354561 (15) | 0.35562 (3) | 0.02654 (8) | |
| S | 0.37975 (7) | 0.14584 (5) | 0.73909 (10) | 0.01703 (11) | |
| O1 | 0.3992 (3) | 0.24027 (18) | 0.6156 (4) | 0.0273 (4) | |
| O2 | 0.5138 (3) | 0.0821 (2) | 0.7893 (5) | 0.0314 (5) | |
| O3 | 0.2560 (2) | 0.08353 (19) | 0.6000 (3) | 0.0250 (4) | |
| O4 | 0.3439 (3) | 0.1767 (2) | 0.9448 (4) | 0.0280 (4) | |
| OW1 | 0.1450 (3) | 0.1085 (2) | 0.1577 (4) | 0.0252 (4) | |
| OW2 | −0.1908 (3) | 0.1109 (2) | 0.0139 (4) | 0.0297 (5) | |
| OW3 | −0.0002 (2) | −0.06342 (18) | 0.2836 (3) | 0.0205 (3) | |
| H11 | 0.184 (7) | 0.093 (5) | 0.277 (11) | 0.050* | |
| H12 | 0.199 (7) | 0.122 (5) | 0.094 (11) | 0.050* | |
| H21 | −0.281 (7) | 0.099 (5) | −0.063 (10) | 0.050* | |
| H22 | −0.181 (7) | 0.166 (5) | −0.017 (11) | 0.050* | |
| H31 | −0.071 (7) | −0.051 (5) | 0.310 (11) | 0.050* | |
| H32 | 0.034 (7) | −0.113 (5) | 0.308 (10) | 0.050* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cu | 0.01750 (19) | 0.0183 (2) | 0.01490 (17) | −0.00407 (15) | 0.00436 (13) | 0.00055 (14) |
| Cs | 0.02807 (11) | 0.02663 (11) | 0.02645 (10) | 0.00196 (6) | 0.01012 (7) | 0.00193 (6) |
| S | 0.0157 (2) | 0.0182 (2) | 0.0169 (2) | −0.00196 (19) | 0.00399 (18) | 0.00030 (19) |
| O1 | 0.0344 (11) | 0.0214 (9) | 0.0283 (10) | −0.0026 (8) | 0.0124 (9) | 0.0051 (8) |
| O2 | 0.0188 (9) | 0.0314 (12) | 0.0407 (12) | 0.0036 (8) | 0.0031 (8) | 0.0038 (10) |
| O3 | 0.0203 (8) | 0.0315 (11) | 0.0219 (8) | −0.0090 (8) | 0.0039 (7) | −0.0048 (8) |
| O4 | 0.0334 (11) | 0.0330 (11) | 0.0197 (8) | −0.0064 (9) | 0.0112 (8) | −0.0049 (8) |
| OW1 | 0.0259 (10) | 0.0295 (11) | 0.0197 (8) | −0.0102 (8) | 0.0055 (7) | −0.0012 (7) |
| OW2 | 0.0231 (10) | 0.0280 (11) | 0.0390 (12) | 0.0030 (9) | 0.0101 (9) | 0.0051 (10) |
| OW3 | 0.0218 (9) | 0.0220 (9) | 0.0197 (8) | 0.0005 (7) | 0.0089 (7) | 0.0030 (7) |
| Cu—OW3 | 1.965 (2) | S—O1 | 1.474 (2) |
| Cu—OW3i | 1.965 (2) | S—O3 | 1.482 (2) |
| Cu—OW1 | 2.005 (2) | S—O4 | 1.484 (2) |
| Cu—OW1i | 2.005 (2) | S—Csv | 3.7066 (7) |
| Cu—OW2i | 2.311 (2) | S—Csvi | 3.7677 (7) |
| Cu—OW2 | 2.311 (2) | S—Csvii | 3.9035 (8) |
| Cs—O1 | 3.098 (2) | O1—Csv | 3.182 (2) |
| Cs—O4ii | 3.114 (2) | O2—Csvi | 3.179 (3) |
| Cs—O3iii | 3.151 (3) | O2—Csv | 3.239 (3) |
| Cs—O2iii | 3.179 (3) | O2—Csvii | 3.528 (3) |
| Cs—O1iv | 3.182 (2) | O3—Csvi | 3.151 (3) |
| Cs—OW2v | 3.233 (3) | O4—Csvii | 3.114 (2) |
| Cs—O2iv | 3.239 (3) | OW1—H11 | 0.77 (7) |
| Cs—OW1 | 3.422 (3) | OW1—H12 | 0.76 (7) |
| Cs—O2ii | 3.528 (3) | OW2—Csiv | 3.233 (3) |
| Cs—Siv | 3.7066 (7) | OW2—H21 | 0.87 (7) |
| Cs—Siii | 3.7677 (7) | OW2—H22 | 0.74 (6) |
| Cs—Sii | 3.9035 (8) | OW3—H31 | 0.75 (7) |
| Cs—H11 | 3.47 (6) | OW3—H32 | 0.70 (7) |
| S—O2 | 1.463 (2) | ||
| OW3—Cu—OW3i | 180.00 (17) | O2iv—Cs—OW1 | 127.78 (6) |
| OW3—Cu—OW1 | 90.34 (9) | O1—Cs—O2ii | 126.34 (6) |
| OW3i—Cu—OW1 | 89.66 (9) | O4ii—Cs—O2ii | 42.23 (6) |
| OW3—Cu—OW1i | 89.66 (9) | O3iii—Cs—O2ii | 82.25 (6) |
| OW3i—Cu—OW1i | 90.34 (9) | O2iii—Cs—O2ii | 61.70 (8) |
| OW1—Cu—OW1i | 180.00 (16) | O1iv—Cs—O2ii | 125.49 (6) |
| OW3—Cu—OW2i | 88.94 (9) | OW2v—Cs—O2ii | 48.26 (6) |
| OW3i—Cu—OW2i | 91.06 (9) | O2iv—Cs—O2ii | 137.77 (8) |
| OW1—Cu—OW2i | 90.60 (10) | OW1—Cs—O2ii | 82.32 (6) |
| OW1i—Cu—OW2i | 89.40 (10) | O2—S—O1 | 109.96 (15) |
| OW3—Cu—OW2 | 91.06 (9) | O2—S—O3 | 108.73 (15) |
| OW3i—Cu—OW2 | 88.94 (9) | O1—S—O3 | 108.61 (14) |
| OW1—Cu—OW2 | 89.40 (10) | O2—S—O4 | 110.66 (16) |
| OW1i—Cu—OW2 | 90.60 (10) | O1—S—O4 | 109.77 (14) |
| OW2i—Cu—OW2 | 180.00 (17) | O3—S—O4 | 109.07 (13) |
| O1—Cs—O4ii | 140.29 (7) | S—O1—Cs | 116.54 (12) |
| O1—Cs—O3iii | 97.49 (6) | S—O1—Csv | 98.82 (11) |
| O4ii—Cs—O3iii | 113.63 (6) | Cs—O1—Csv | 119.34 (7) |
| O1—Cs—O2iii | 141.84 (6) | S—O2—Csvi | 102.10 (12) |
| O4ii—Cs—O2iii | 73.76 (6) | S—O2—Csv | 96.71 (12) |
| O3iii—Cs—O2iii | 44.43 (6) | Csvi—O2—Csv | 99.31 (8) |
| O1—Cs—O1iv | 97.59 (5) | S—O2—Csvii | 93.62 (13) |
| O4ii—Cs—O1iv | 83.64 (6) | Csvi—O2—Csvii | 118.30 (8) |
| O3iii—Cs—O1iv | 126.51 (6) | Csv—O2—Csvii | 137.77 (8) |
| O2iii—Cs—O1iv | 104.49 (6) | S—O3—Csvi | 102.83 (11) |
| O1—Cs—OW2v | 81.11 (6) | S—O4—Csvii | 111.17 (13) |
| O4ii—Cs—OW2v | 87.04 (6) | Cu—OW1—Cs | 134.36 (11) |
| O3iii—Cs—OW2v | 69.69 (6) | Cu—OW1—H11 | 113 (5) |
| O2iii—Cs—OW2v | 85.68 (7) | Cs—OW1—H11 | 87 (5) |
| O1iv—Cs—OW2v | 163.61 (6) | Cu—OW1—H12 | 112 (5) |
| O1—Cs—O2iv | 94.88 (6) | Cs—OW1—H12 | 97 (5) |
| O4ii—Cs—O2iv | 111.81 (6) | H11—OW1—H12 | 112 (6) |
| O3iii—Cs—O2iv | 83.77 (6) | Cu—OW2—Csiv | 134.73 (10) |
| O2iii—Cs—O2iv | 80.69 (8) | Cu—OW2—H21 | 122 (4) |
| O1iv—Cs—O2iv | 43.99 (6) | Csiv—OW2—H21 | 75 (4) |
| OW2v—Cs—O2iv | 152.24 (6) | Cu—OW2—H22 | 114 (5) |
| O1—Cs—OW1 | 67.15 (6) | Csiv—OW2—H22 | 101 (5) |
| O4ii—Cs—OW1 | 73.24 (6) | H21—OW2—H22 | 101 (6) |
| O3iii—Cs—OW1 | 144.36 (5) | Cu—OW3—H31 | 110 (5) |
| O2iii—Cs—OW1 | 142.85 (6) | Cu—OW3—H32 | 117 (5) |
| O1iv—Cs—OW1 | 88.33 (6) | H31—OW3—H32 | 122 (7) |
| OW2v—Cs—OW1 | 76.06 (6) |
| Symmetry codes: (i) −x, −y, −z; (ii) x−1/2, −y+1/2, z−1; (iii) −x+1/2, y+1/2, −z+1; (iv) x−1/2, −y+1/2, z; (v) x+1/2, −y+1/2, z; (vi) −x+1/2, y−1/2, −z+1; (vii) x+1/2, −y+1/2, z+1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| OW1—H11···O3 | 0.77 (7) | 1.97 (7) | 2.714 (2) | 166 (7) |
| OW1—H12···O4viii | 0.75 (7) | 1.99 (7) | 2.738 (4) | 173 (7) |
| OW2—H21···O2ix | 0.87 (6) | 1.91 (7) | 2.777 (3) | 174 (7) |
| OW2—H22···O4ii | 0.74 (6) | 2.04 (6) | 2.779 (4) | 171 (6) |
| OW3—H31···O3x | 0.74 (7) | 2.02 (7) | 2.725 (3) | 155 (7) |
| OW3—H32···O1vi | 0.71 (7) | 1.99 (6) | 2.693 (3) | 171 (6) |
| Symmetry codes: (viii) x, y, z−1; (ix) x−1, y, z−1; (ii) x−1/2, −y+1/2, z−1; (x) −x, −y, −z+1; (vi) −x+1/2, y−1/2, −z+1. |
| Cu—OW3 | 1.965 (2) | Cs—OW2iv | 3.233 (3) |
| Cu—OW1 | 2.005 (2) | Cs—O2iii | 3.239 (3) |
| Cu—OW2 | 2.311 (2) | Cs—OW1 | 3.422 (3) |
| Cs—O1 | 3.098 (2) | Cs—O2i | 3.528 (3) |
| Cs—O4i | 3.114 (2) | S—O2 | 1.463 (2) |
| Cs—O3ii | 3.151 (3) | S—O1 | 1.474 (2) |
| Cs—O2ii | 3.179 (3) | S—O3 | 1.482 (2) |
| Cs—O1iii | 3.182 (2) | S—O4 | 1.484 (2) |
| O2—S—O1 | 109.96 (15) | O2—S—O4 | 110.66 (16) |
| O2—S—O3 | 108.73 (15) | O1—S—O4 | 109.77 (14) |
| O1—S—O3 | 108.61 (14) | O3—S—O4 | 109.07 (13) |
| Symmetry codes: (i) x−1/2, −y+1/2, z−1; (ii) −x+1/2, y+1/2, −z+1; (iii) x−1/2, −y+1/2, z; (iv) x+1/2, −y+1/2, z. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| OW1—H11···O3 | 0.77 (7) | 1.97 (7) | 2.714 (2) | 166 (7) |
| OW1—H12···O4v | 0.75 (7) | 1.99 (7) | 2.738 (4) | 173 (7) |
| OW2—H21···O2vi | 0.87 (6) | 1.91 (7) | 2.777 (3) | 174 (7) |
| OW2—H22···O4i | 0.74 (6) | 2.04 (6) | 2.779 (4) | 171 (6) |
| OW3—H31···O3vii | 0.74 (7) | 2.02 (7) | 2.725 (3) | 155 (7) |
| OW3—H32···O1viii | 0.71 (7) | 1.99 (6) | 2.693 (3) | 171 (6) |
| Symmetry codes: (v) x, y, z−1; (vi) x−1, y, z−1; (i) x−1/2, −y+1/2, z−1; (vii) −x, −y, −z+1; (viii) −x+1/2, y−1/2, −z+1. |
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The title compound Cs2[Cu(H2O)6](SO4)2 is a member of the isotypic series known as Tutton's salts. Their general formula is MI2[MII(H2O)6](XO4)2, where MI and MII are, respectively, a monovalent and a divalent cation and X is hexavalent S, Se or Cr. The structure of Tutton's salts consists of isolated [MII(H2O)6] octahedra and XO42− tetrahedra connected by the MI cation (Fig. 1). As a result sheets parallel to (100) are formed, interconnected via medium to weak hydrogen bonds originating from the aqua ligands of the MII cations to the acceptors of the sulfate groups.
The structure of the title compound has been previously determined by Shields & Kennard (1972) from single-crystal neutron data. However, the original data were characterized by large standard uncertainties of cell parameters and fractional coordinates. Moreover, no displacement parameters were reported. Because of the requirements of accurate structural data to rationalize the crystal chemistry of Tutton's salts, we decided to carry out a redetermination of the crystal structure of Cs2[Cu(H2O)6](SO4)2 based on single-crystal X-ray data. The refined cell parameters and the cell volume differ significantly from the reference data [P21/a, a = 9.42 (1), b = 12.785 (9), c = 6.28 (1) Å, β = 105.9 (1) °, (Shields & Kennard, 1972)]. The sulfate group is slightly distorted and, similarly to all Tutton's salts, the S—O2 distance is smaller (1.463 (2) Å) than the remaining three S—O distances (1.474 (2)–1.484 (2) Å) because of bond-valence requirements. The mean Cu—O distance of the [Cu(H2O)6] octahedron is 2.094 Å. This value compares favourably with the range between 2.085 and 2.098 Å as reported for other MI2[Cu(H2O)6](SO4)2 salts (NH4: Cotton et al., 1993; K: Simmons et al., 2006; Rb: Ballirano & Belardi, 2007). The [Cu(H2O)6] octahedron is strongly distorted as a result of the Jahn-Teller effect. The calculated distortion parameter Δ, as defined by Brown & Shannon (1973), amounts to 0.0054. The Cs+ cation is coordinated by seven O atoms and two water molecules with a mean Cs—O distance of 3.238 Å. The refined hydrogen atom positions are not defined with high accuracy. However, after value normalization following the procedure given by Jeffrey & Lewis (1978) and Taylor & Kennard (1983), reasonable H···O distances in the range between 1.765 and 1.850 Å were obtained. Both O1 and O2 atoms are acceptors of a single hydrogen bond, whereas O3 and O4 are acceptors of two hydrogen bonds. As a result, a shortening of the distances H32···O1 and of S—O2 is observed.