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Acta Crystallogr Sect E Struct Rep Online. 2009 April 1; 65(Pt 4): i23–i24.
Published online 2009 March 6. doi:  10.1107/S1600536809006874
PMCID: PMC2968889

[Cu2(HF2)(H2O)8][FeF6]·2H2O

Abstract

The title compound, octaaqua­(hydrogenfluorido)dicopper(II) hexa­fluoridoferrate(III) dihydrate, was synthesized under hydro­thermal conditions. The Cu atom is coordinated by one F and five O atoms within a highly distorted octa­hedron, forming dimeric [Cu2(H2O)8HF2]3+ units by edge sharing. These units are hydrogen bonded to [FeF6]3− anions and to an inter­stitial water mol­ecule. The former feature Fe3+ on a special position (An external file that holds a picture, illustration, etc.
Object name is e-65-00i23-efi1.jpg). The dimeric copper units are linked to adjacent dimers by F—H(...)F hydrogen bonds. Additional O—H(...)O and O—H(...)F hydrogen bonds help to consolidate the crystal packing.

Related literature

For other hydrated copper-iron fluorides, see: Kummer & Babel (1987 [triangle]); Leblanc & Ferey (1990 [triangle]). For F(...)F distances, see: Frevel & Rinn (1962 [triangle]); Massa & Herdtweck (1983 [triangle]). For asymmetrical F—H(...)F hydrogen bonding, see: Roesky et al. (1990 [triangle]); Gerasimenko et al. (2007 [triangle]); Gerken et al. (2002 [triangle]). For Pb8MnFe2F24, see: Le Bail & Mercier (1992 [triangle]). For valence-bond analysis, see: Brown & Altermatt (1985 [triangle]); Brese & O’Keeffe (1991 [triangle]).

Experimental

Crystal data

  • [Cu2(HF2)(H2O)8][FeF6]·2H2O
  • M r = 516.12
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-00i23-efi2.jpg
  • a = 6.659 (2) Å
  • b = 7.450 (3) Å
  • c = 8.377 (5) Å
  • α = 107.37 (4)°
  • β = 106.89 (5)°
  • γ = 94.26 (3)°
  • V = 373.6 (3) Å3
  • Z = 1
  • Mo Kα radiation
  • μ = 3.91 mm−1
  • T = 293 K
  • 0.11 × 0.10 × 0.05 mm

Data collection

  • Siemens AED2 diffractometer
  • Absorption correction: gaussian (SHELX76; Sheldrick, 2008 [triangle]) T min = 0.698, T max = 0.845
  • 3303 measured reflections
  • 3303 independent reflections
  • 2044 reflections with I > 2σ(I)
  • 3 standard reflections frequency: 120 min intensity decay: 15%

Refinement

  • R[F 2 > 2σ(F 2)] = 0.040
  • wR(F 2) = 0.080
  • S = 1.00
  • 3303 reflections
  • 133 parameters
  • 15 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.62 e Å−3
  • Δρmin = −0.63 e Å−3

Data collection: STADI4 (Stoe & Cie, 1998 [triangle]); cell refinement: STADI4; data reduction: X-RED (Stoe & Cie, 1998 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Brandenburg, 1999 [triangle]) and ORTEP-3 (Farrugia, 1997 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2009 [triangle]).

Table 1
Selected bond lengths (Å)
Table 2
Hydrogen-bond geometry (Å, °)
Table 3
Valence-bond analysis according to the empirical expression from Brown & Altermatt (1985 [triangle]), using parameters for solids from Brese & O’Keeffe (1991 [triangle])

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809006874/fi2069sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809006874/fi2069Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

Thanks are due to M. Leblanc for the single-crystal data collection.

supplementary crystallographic information

Comment

[Cu(H2O)4H0.5F]2(FeF6)(H2O)2 is the third hydrated copper–iron fluoride, the two previous ones being Cu3Fe2F12(H2O)12 (Kummer & Babel, 1987) and CuFe2F8(H2O)2 (Leblanc & Ferey, 1990). In this new compound, an almost perfect (FeF6)3- octahedron, placed on an inversion center, is connected exclusively by hydrogen bonding to edge-sharing bi-octahedral [Cu2(H2O)8HF2]3+ units and to an interstitial water molecule. The copper atom can be considered to be five-coordinated by four water molecules and one F atom in the fashion of a square pyramid (Figure 1). The square is constituted by the F atom and three water molecules at distances in the 1.906–1.977 Å range (Table 1), whereas Ow(4), at the top of the pyramid is at 2.349 Å (Jahn-Teller distortion). However, if one considers the next neighbour Ow(3) at 2.715 Å as sixth ligand, thecoordination can be described as very distorted octahedral, yielding centrosymmetric, dimeric units with a Cu—Cu distance of 3.575 Å. The dimers are bonded to adjacent dimers through F(4) by a HF2- ion (figure 2), however the F—F distance (2.597 Å) is much larger (Table 2) than usually observed (2.27 Å in LiHF2 (Frevel & Rinn, 1962), 2.28 in BaHF3 (Massa & Herdtweck, 1983). Moreover, the hydrogen atom H(6) which would have been expected at the 1/2, 1/2, 1/2 special position, exactly at the middle of the F(4)—F(4) atoms, in order to form a linear (F—H—F)- ion, was seen on the Fourier difference map as occupying more probably half a general position. It is then more a F—H···F bridge than a F—H—F one. Such asymmetrical F—H···F hydrogen bonding was observed in many cases for F—F distances going up to 2.686 Å in [(η5-C5Me5)NbF4(HF)AsF3]2 (Roesky et al., 1990), 2.429 to 2.512 Å in [OsO3F](HF)2[AsF6] (Gerken et al., 2002), 2.326 to 2.402 Å in Rb2-xKxZrF6(HF)2 (Gerasimenko et al., 2007).

The charge of the cations is balanced by the centrosymmetric anion [FeF6]3–. There are 14 water molecules around the (FeF6)3- octahedron, the H(51) atom corresponds to a bifurcated hydrogen bond towards F(2) and F(3) (figure 3). This helps the bond valence calculations to provide relatively satisfying results (Table 3), the largest disagreements being on O(4) and F(4). The contribution from the long Cu—Ow(3) distance is negligible.

Comparing with the Cu3Fe2F12(H2O)12 crystal structure (Kummer & Babel, 1987), also triclinic, there are strong differences. The three copper atoms and two Fe atoms are all placed on inversion centers. One (FeF6)3- octahedron is isolated, and the other forms chiolite-like square meshes by sharing F corners with tetra-hydrated Cu(H2O)4F2 elongated octahedra (the long distances are the two Cu—F ones, close to 2.32 Å for the three independent copper sites). In CuFe2F8(H2O)2 (Leblanc & Ferey, 1990), the CuF4(H2O)2 octahedra show two long Cu—F distances (2.451 Å). So, in both cases, the long distances are Cu—F ones, which is not the case of the title compound.

A study of the magnetic properties is currently in progress.

Experimental

Hydrothermal growth at 493 K from (2PbF2/2CuF2/FeF3) in HF 5M or 1M solutions, produced large crystals which could be identified as corresponding to Cu3Fe2F12(H2O)12 (Kummer & Babel, 1987) (5M solution) or to the title compound (1M). Both compounds are occurring with the same intense blue color and could have been confused if no powder pattern had been recorded. At other starting compositions, mixtures of both compounds could be observed, and also together especially with Pb8CuFe2F24 (starting from 2PbF2/CuF2/2FeF3 for instance), isostructural with Pb8MnFe2F24 (Le Bail & Mercier, 1992).

Refinement

The hydrogen atoms were all located on the difference Fourier map. Those of the water molecules were restrained to have Ow—H and H—H distances respectively close to 1.0 and 1.59 Å, their Uiso values were refined by groups of two. The hydrogen atom of the HF group was let at its difference Fourier map position with a fixed Uiso.

Figures

Fig. 1.
ORTEP-3 view (Farrugia, 1997) of the FeF63- octahedron, the isolated water molecule and the Cu(H2O)4F+ square-based pyramid which is forming octahedra dimeric units when considering the very long Cu-O3 distance (2.715Å). Displacement ellipsoids ...
Fig. 2.
Crystal packing with view along [010]. Hydrogen bonding is shown as dashed lines. Copper coordination shown as distorted octahedra (adding O(3) at 2.715 Å from Cu) sharing an edge.
Fig. 3.
The 14 water molecules, from the Cu coordination sphere or isolated, involved in hydrogen bonding with the FeF63- octahedron.

Crystal data

[Cu2(H2F)(H2O)8][FeF6]·2H2OZ = 1
Mr = 516.12F(000) = 257
Triclinic, P1Dx = 2.294 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71069 Å
a = 6.659 (2) ÅCell parameters from 28 reflections
b = 7.450 (3) Åθ = 2.7–35°
c = 8.377 (5) ŵ = 3.91 mm1
α = 107.37 (4)°T = 293 K
β = 106.89 (5)°Platelet, blue
γ = 94.26 (3)°0.11 × 0.10 × 0.05 mm
V = 373.6 (3) Å3

Data collection

Siemens AED2 diffractometer2044 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.0000
graphiteθmax = 35.0°, θmin = 2.7°
2θ/ω scansh = −10→10
Absorption correction: gaussian (SHELX76; Sheldrick, 2008)k = −12→11
Tmin = 0.698, Tmax = 0.845l = 0→13
3303 measured reflections3 standard reflections every 120 min
3303 independent reflections intensity decay: 15%

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.080w = 1/[σ2(Fo2) + (0.03P)2] where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max = 0.004
3303 reflectionsΔρmax = 0.62 e Å3
133 parametersΔρmin = −0.63 e Å3
15 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0072 (17)

Special details

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)

xyzUiso*/UeqOcc. (<1)
Cu0.60473 (5)0.55727 (4)0.23479 (4)0.01662 (8)
Fe0.00000.00000.00000.01433 (10)
F10.2310 (3)−0.0246 (2)−0.0944 (2)0.0270 (3)
F20.2029 (3)0.1318 (2)0.2331 (2)0.0275 (3)
F3−0.0278 (3)0.2400 (2)−0.0437 (2)0.0272 (4)
F40.4365 (3)0.5885 (3)0.3872 (2)0.0338 (4)
O10.5648 (3)0.2890 (3)0.2113 (3)0.0283 (4)
O20.5992 (3)0.8217 (3)0.2411 (3)0.0244 (4)
O30.7470 (3)0.5094 (3)0.0530 (3)0.0219 (4)
O40.9139 (3)0.6601 (3)0.4849 (3)0.0262 (4)
O50.2376 (4)0.8884 (3)0.4476 (3)0.0291 (4)
H110.641 (6)0.188 (5)0.158 (6)0.064 (10)*
H120.424 (5)0.226 (6)0.201 (6)0.064 (10)*
H210.667 (7)0.876 (7)0.167 (5)0.084 (12)*
H220.604 (8)0.935 (5)0.341 (5)0.084 (12)*
H310.866 (7)0.623 (6)0.067 (8)0.117 (16)*
H320.829 (8)0.398 (6)0.022 (8)0.117 (16)*
H410.937 (15)0.679 (15)0.615 (5)0.24 (3)*
H421.049 (10)0.734 (13)0.487 (12)0.24 (3)*
H510.211 (11)0.909 (10)0.330 (6)0.16 (2)*
H520.315 (12)0.770 (8)0.430 (10)0.16 (2)*
H60.42190.49790.43750.080*0.50

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cu0.02080 (15)0.01342 (14)0.01901 (15)0.00339 (11)0.01121 (12)0.00561 (11)
Fe0.0157 (2)0.0129 (2)0.0174 (2)0.00267 (17)0.00901 (19)0.00591 (18)
F10.0276 (8)0.0268 (8)0.0391 (9)0.0100 (6)0.0248 (7)0.0139 (7)
F20.0255 (8)0.0296 (8)0.0217 (8)−0.0025 (6)0.0064 (6)0.0038 (6)
F30.0295 (8)0.0181 (7)0.0442 (10)0.0077 (6)0.0185 (8)0.0176 (7)
F40.0475 (11)0.0338 (9)0.0375 (10)0.0184 (8)0.0290 (9)0.0192 (8)
O10.0285 (10)0.0151 (8)0.0470 (13)0.0038 (7)0.0227 (9)0.0086 (8)
O20.0386 (11)0.0138 (8)0.0261 (10)0.0040 (7)0.0177 (8)0.0074 (7)
O30.0270 (9)0.0179 (8)0.0281 (10)0.0056 (7)0.0191 (8)0.0079 (7)
O40.0243 (9)0.0267 (10)0.0261 (10)0.0042 (8)0.0076 (8)0.0074 (8)
O50.0359 (11)0.0279 (10)0.0264 (10)0.0109 (9)0.0128 (9)0.0093 (8)

Geometric parameters (Å, °)

Cu—F41.9058 (19)F2—O5v2.888 (3)
Cu—O11.939 (2)F3—O3iii2.577 (2)
Cu—O21.958 (2)F3—O3vi2.668 (3)
Cu—O31.977 (2)F3—O5vii3.072 (4)
Cu—O42.349 (3)F4—F4iv2.597 (4)
Fe—F11.9204 (16)F4—O12.632 (3)
Fe—F2i1.930 (2)F4—O52.676 (3)
Fe—F31.9402 (17)F4—O22.730 (3)
F1—O1ii2.590 (3)F4—O43.006 (3)
F1—O2iii2.595 (3)O1—O32.804 (3)
F1—F22.709 (3)O2—O5viii2.699 (3)
F1—F3i2.728 (2)O2—O32.814 (3)
F1—F32.732 (2)O2—O43.061 (3)
F1—F2i2.736 (3)O2—O3iii3.113 (4)
F1—O13.051 (4)O3—O3iii3.128 (4)
F2—O12.679 (3)O4—O4ix2.768 (4)
F2—F3i2.714 (3)O4—O5x2.793 (3)
F2—F32.759 (3)Cu—O3iii2.715 (3)
F2—O4iv2.766 (3)Cu—Cuiii3.575 (3)
F4—Cu—O186.42 (9)F1i—Fe—F2i89.43 (9)
F4—Cu—O289.89 (8)F1—Fe—F390.08 (7)
O1—Cu—O2171.49 (9)F1i—Fe—F389.92 (7)
F4—Cu—O3173.09 (9)F2i—Fe—F389.06 (9)
O1—Cu—O391.47 (9)F2—Fe—F390.94 (9)
O2—Cu—O391.30 (8)H11—O1—H12109 (3)
F4—Cu—O489.27 (9)H21—O2—H22104 (3)
O1—Cu—O497.50 (10)H31—O3—H3298 (3)
O2—Cu—O490.11 (9)H41—O4—H42103 (4)
O3—Cu—O497.53 (9)H51—O5—H52102 (3)
F1—Fe—F2i90.57 (9)

Symmetry codes: (i) −x, −y, −z; (ii) −x+1, −y, −z; (iii) −x+1, −y+1, −z; (iv) −x+1, −y+1, −z+1; (v) x, y−1, z; (vi) x−1, y, z; (vii) −x, −y+1, −z; (viii) −x+1, −y+2, −z+1; (ix) −x+2, −y+1, −z+1; (x) x+1, y, z.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1—H11···F1ii1.00 (4)1.59 (4)2.590 (3)173 (4)
O1—H12···F20.99 (4)1.71 (4)2.679 (3)167 (4)
O2—H21···F1iii1.02 (5)1.61 (5)2.595 (3)161 (4)
O2—H22···O5viii0.98 (4)1.82 (4)2.699 (3)147 (5)
O3—H31···F3iii1.07 (5)1.52 (5)2.577 (2)167 (5)
O3—H32···F3x1.04 (5)1.64 (5)2.668 (3)171 (5)
O4—H41···F2iv1.02 (4)2.07 (9)2.766 (3)123 (8)
O4—H42···O5x1.01 (9)1.81 (9)2.793 (3)164 (8)
O5—H51···F2xi1.01 (6)2.05 (7)2.888 (3)139 (5)
O5—H51···F3vii1.01 (6)2.23 (5)3.072 (4)140 (6)
O5—H52···F41.05 (7)1.63 (7)2.676 (3)175 (6)
F4—H6···F4iv0.911.822.597 (4)142

Symmetry codes: (ii) −x+1, −y, −z; (iii) −x+1, −y+1, −z; (viii) −x+1, −y+2, −z+1; (x) x+1, y, z; (iv) −x+1, −y+1, −z+1; (xi) x, y+1, z; (vii) −x, −y+1, −z.

Table 3 Valence-bond analysis according to the empirical expression from Brown &amp; Altermatt (1985), using parameters for solids from Brese &amp; O'Keeffe (1991)

O1O2O3O4F4F1F2F3O5ΣΣ expected
Cu0.490.470.450.160.442.012
Fe0.51 (x2)0.49 (x2)0.48 (x2)2.963
H110.800.2011
H120.800.2011
H210.800.2011
H220.800.2011
H310.800.2011
H410.800.2011
H420.800.2011
H510.100.100.8011
H520.200.8011
H60.80 (x0.5)11
0.20 (x0.5)
Σ2.092.072.051.761.140.910.990.982.00
Σexpected222211112

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FI2069).

References

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