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The title crystal structure, Cs[ReCl4O2], consists of cis-tetra­chlorido­dioxido­rhenate(VII) anions and caesium cations. The distorted octa­hedral anion has nearly C2v symmetry, with a cis arrangement of the oxide ligands. The Re-Cl bond lengths for the Cl atoms trans to the oxide ligands are affected by the trans influence of the Re-O bonds and are longer than for the Cl atoms cis to the oxide ligands [average of 2.472 (2) Å versus average of 2.322 (2) Å, respectively]. There are ten Cl atoms from six cis-tetra­chlorido­dioxido­rhenate(VII) anions in the neighbourhood of the caesium cation.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107067996/iz3041sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107067996/iz3041Isup2.hkl
Contains datablock I

Comment top

Tetrachloridodioxidorhenate(VII) anions were initially studied as the first-stage yellow product in the reaction between gaseous hydrogen chloride and rhenate(VII) anions by Jeżowska-Trzebiatowska (1951). Crystal structures containing tetrachloridodioxidorhenate(VII) anions were recently reported by Supeł & Seppelt (2007) in the form of the tetraethylphosphonium salt and also as the [NO][ReO2Cl4] salt. As far as the present authors' knowledge is concerned, the only other structure report of an [ReO2X4]- anion (X = halogen) was published for the [ReO2F4]- anion as the lithium salt (Casteel et al., 1999).

In this paper we report a simple method of obtaining unstable crystals of caesium cis-tetrachloridodioxidorhenate(VII), (I), and its crystal structure at 110 (2) K. This compound is one of the unstable crystalline products that it is possible to obtain in the reaction of caesium rhenate(VII) with acetyl chloride (see Experimental).

The crystal structure of (I) consists of cis-tetrachloridodioxidorhenate(VII) anions and caesium cations. In the distorted-octahedral cis-tetrachloridodioxidorhenate(VII) anion of nearly C2v symmetry (Fig. 1), the two oxide ligands (O1 and O2) are in a cis arrangement. Such a cis arrangement of the oxide ligands is expected for a d0 electron configuration of the central metal ion (Barea et al., 1998). This is contrary to, for example, the d2 configuration, where, based on molecular orbital calculations, the trans arrangement is favoured (Demachy & Jean, 1997). This symmetry, as well as the geometric parameters of the anion, corresponds very well to the data reported by Supeł & Seppelt (2007). In the tetraethylphosphonium salt (Supeł & Seppelt, 2007), the Re—O bond lengths are 1.692 (1) and 1.707 (1) Å, the Re—Clcis bond lengths are 2.3225 (5) and 2.3302 (5) Å, the Re—Cltrans bond lengths are 2.4417 (4) and 2.4453 (5) Å, and the O—Re—O bond angle is 102.31 (7)°.

In the original paper reporting the crystal structure of [NO][ReO2Cl4] (Supeł & Seppelt, 2007), a difference Fourier peak of 5.28 electrons was present, which could come from partial disorder. Refinement based on the original reflection data obtained from the former authors was performed. Although the inclusion of the highest peak in the new refinement resulted in a drop in the R value, we were unable to propose any disorder model better than the previously published model without disorder. It seems that in the reported crystal structure of [NO][ReO2Cl4], only the geometric parameters of the second anion are affected by disorder. Therefore, these parameters will not be taken into account in the summary concerning the geometry of the ReO2 moiety in [ReO2X4]- anions.

The Re—O bond lengths reported here [1.695 (3) and 1.703 (3) Å] are also comparable with the corresponding values published for the Re—O bond lengths in the [ReO2F4]- anion in its lithium salt [the anion can be described with only one Re—O bond length, 1.678 (9) Å, as only half of the anion is symmetry independent; Casteel et al., 1999]. All in all, according to the data reported so far, and taking into account the present report, the Re—O bond lengths in the cis-ReO2 moiety in [ReO2X4]- anions should be approximately 1.70 Å.

Based on the aforementioned results, some general conclusions concerning the [ReO2Cl4]- anion geometry can be made and the obtained values of the geometric parameters can be compared with the analogous rhenium d2 system with a trans arrangement of the oxide ligands. A survey of the current literature on rhenium compounds reveals an example of a compound suitable for this purpose, potassium dioxidotetracyanorhenate(V). The crystal structure of this complex was first determined by Łukaszewicz & Głowiak (1961), then by Murmann & Schlemper (1971), and finally by neutron diffraction by Fenn et al. (1971). The criterion of the suitability of this compound consists of the presence of two oxide ligands in a trans arrangement, ReV as the central metal atom, and four remaining ligands of the same kind and possibly resembling chloride ligands. In this crystal structure, the complex trans-[ReO2(CN)4]3- anions differ from the cis-[ReO2Cl4]- anions by the oxidation state of the central Re atom (ReV instead of ReVII), as well as by the arrangement of the two oxide ligands (trans instead of cis) and the type of the four remaining ligands (cyano instead of chloride ligands). The Re—O bond length reported for this compound (Murmann & Schlemper, 1971) is 1.781 (3) Å. This means that, in the trans-dioxidorhenium(V) moiety, the Re—O bond should be 0.6–0.8 Å longer than in the cis-dioxidorhenium(VII) moiety.

The Re–Cl bond lengths reported here for the Cl ligands cis to the oxide ligands (Cl3 and Cl4) are 2.330 (2) and 2.313 (2) Å, respectively. The distances of the Cl ligands trans to the oxide ligands (Cl1 and Cl2) from the central Re1 atom are longer [2.472 (2) and 2.471 (2) Å, respectively]. These values for the Re—Cltrans bond lengths are comparable with the analogous values published for other rhenium(VII) compounds. For cis-tetrachloridodioxidorhenate(VII) anions, Supeł & Seppelt (2007) reported values of 2.4417 (4) and 2.4453 (5) Å in the tetraethylphosphonium salt, and 2.488 (2) and 2.529 (2) Å for [NO]ReO2Cl4. In caesium cis-trichloridotrioxidorhenate(VII) reported by Lis (1983), the Re—Cltrans bond lengths are 2.517 (8) and 2.494 (5) Å. In another example, ReO3Cl(THF)2 reported by Noh & Girolami (2007), the Re—Cltrans bond length is 2.427 (2) Å. In all these cases, the lengthening of the Re—Cl bond is the result of the trans influence of the Re—O bond (Shustorovich et al., 1975). Based on these data, it seems that the Re—Cltrans (to the oxide O atom) bond should be as much as 0.10–0.25 Å longer than the Re—Clcis bond.

There are ten Cl atoms from six cis-tetrachloridodioxidorhenate(VII) anions in the neighbourhood of the Cs+ cation, at distances in the range 3.50–3.73 Å (see Table 2 for symmetry codes and the shortest interatomic distances; Fig. 2). Two anions are in contact with the Cs+ cation via three Cl ligands (Cl1iv, Cl2iv and Cl4iv, and Cl3i, Cl1i and Cl2i). Four anions are in contact via only one Cl ligand (Cl1, Cl3ii, Cl1iii and Cl4v). For one cis-tetrachloridodioxidorhenate(VII) anion in contact with the Cs+ cation via the Cl2 ligand, an additional contact involving the O1 ligand can be distinguished (Table 1). Thus, the Cs+ cation is surrounded by 11 ligands from ten anions, lying in the vertices of a `staggered 164 stack' based on the considerations of King (1970).

The crystal structure is stabilized by a three-dimensional network of short Cs···Cl contacts (Fig. 3). The shortest distance between two Cs+ cations is approximately 4.85 Å. The shortest intermolecular distance between two Re centres from two independent anions is approximately 4.73 Å.

Related literature top

For related literature, see: Barea et al. (1998); Casteel et al. (1999); Demachy & Jean (1997); Fenn et al. (1971); Jeżowska-Trzebiatowska (1951); King (1970); Lis (1983); Murmann & Schlemper (1971); Noh & Girolami (2007); Sheldrick (2008); Shustorovich et al. (1975); Supeł & Seppelt (2007); Łukaszewicz & Głowiak (1961).

Experimental top

All operations were performed at room temperature. Caesium rhenate(VII) (0.05 g) was placed in a glass vessel and acetyl chloride (0.2 ml) was added. The vessel was covered with Parafilm. The mixture turned slowly orange and then red with dissolution of the solid rhenate(VII). At this stage, the vessel was covered with a plastic cap. After 1 d, extremely unstable crystals in the form of plates, difficult to handle and reproduce, began to precipitate. Part of the solution with the precipitated crystals was quickly placed on a cool plate, cooled to about 258 K under a nitrogen atmosphere and covered with perfluoroalkylether. All these operations were intended to avoid the decomposition of the crystals. A single-crystal was selected from the cooled mixture and a preliminary X-ray diffraction measurement showed it likely to be composed of caesium cis-tetrachloridodioxidorhenate(VII) acetic anhydride solvate. The measurement provided only the crystal structure model, as the crystals were extremely unstable and some decomposition occurred before they were mounted on the diffractometer. This could lead to the conclusion concerning the apparent reaction shown in the scheme.

After a week, in the remaining reaction mixture among the orange plates, red blocks began to appear with another kind of unstable orange plates. Application of a similar procedure to that described above enabled the performance of X-ray diffraction measurements for both new kinds of crystals. The red blocks consisted of caesium pentachloridooxidorhenate(VI) and the new kind of orange plates consisted of the title compound. Interestingly, the same reaction of acetyl chloride with caesium rhenate(VII) performed at about 267 K yields orange crystals in the form of needles with the same composition as the title compound. At further reaction stages, the red mixture in contact with air turned violet and underwent decomposition to caesium rhenate(VII).

Refinement top

The structure was solved using the Patterson method in SHELXS97 (Sheldrick, 2008).

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Bruker, 1997) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. A view of the cis-tetrachloridodioxidorhenate(VII) anion, with the atom-labelling scheme.
[Figure 2] Fig. 2. The nearest neighbours of the Cs+ cation. The debatable contact to atom O1 (see Comment) is denoted with a dashed line [No dashed line is visible - please revise diagram]. [Symmetry codes: (i) -x + 1, -y + 2, -z + 1; (ii) x, -y + 3/2, z + 1/2; (iii) x - 1, -y + 3/2, z + 1/2; (iv) x - 1, y, z; (v) -x + 1, y + 1/2, -z + 3/2.]
[Figure 3] Fig. 3. A view of the packing in the crystal structure, showing the three-dimensional network of short Cs···Cl contacts (heavy lines; see Comment). [Symmetry code: (vi) -x, 1 - y, 1 - z.]
Caesium cis-tetrachloridodioxidorhenate(VII)' top
Crystal data top
Cs[ReCl4O2]F(000) = 856
Mr = 492.91Dx = 4.102 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 9641 reflections
a = 6.609 (3) Åθ = 3–35°
b = 10.322 (5) ŵ = 20.98 mm1
c = 11.714 (5) ÅT = 110 K
β = 92.04 (5)°Plate, orange
V = 798.6 (6) Å30.11 × 0.11 × 0.07 mm
Z = 4
Data collection top
Oxford Diffraction XcaliburPX CCD
diffractometer
4462 independent reflections
Radiation source: fine-focus sealed tube2402 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.057
ω and ϕ scansθmax = 42.0°, θmin = 5.0°
Absorption correction: analytical
(ABSPACK and analytical correction; Oxford Diffraction, 2006)
h = 118
Tmin = 0.164, Tmax = 0.296k = 1913
14688 measured reflectionsl = 2221
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.032Secondary atom site location: difference Fourier map
wR(F2) = 0.034 w = 1/[σ2(Fo2)]
where P = (Fo2 + 2Fc2)/3
S = 0.77(Δ/σ)max = 0.002
4462 reflectionsΔρmax = 1.52 e Å3
73 parametersΔρmin = 1.59 e Å3
Crystal data top
Cs[ReCl4O2]V = 798.6 (6) Å3
Mr = 492.91Z = 4
Monoclinic, P21/cMo Kα radiation
a = 6.609 (3) ŵ = 20.98 mm1
b = 10.322 (5) ÅT = 110 K
c = 11.714 (5) Å0.11 × 0.11 × 0.07 mm
β = 92.04 (5)°
Data collection top
Oxford Diffraction XcaliburPX CCD
diffractometer
4462 independent reflections
Absorption correction: analytical
(ABSPACK and analytical correction; Oxford Diffraction, 2006)
2402 reflections with I > 2σ(I)
Tmin = 0.164, Tmax = 0.296Rint = 0.057
14688 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03273 parameters
wR(F2) = 0.0340 restraints
S = 0.77Δρmax = 1.52 e Å3
4462 reflectionsΔρmin = 1.59 e Å3
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Re10.67638 (3)0.688959 (13)0.447624 (14)0.01305 (4)
Cs10.18718 (4)0.88921 (2)0.65308 (2)0.01490 (6)
Cl30.52127 (14)0.82298 (8)0.31048 (8)0.0155 (2)
Cl10.99603 (14)0.78427 (8)0.38315 (8)0.0158 (2)
Cl20.68494 (13)0.88663 (8)0.56669 (8)0.01300 (19)
Cl40.87935 (15)0.60021 (8)0.59234 (8)0.0190 (2)
O10.4549 (4)0.6505 (2)0.5080 (2)0.0212 (7)
O20.7095 (4)0.5656 (2)0.3535 (2)0.0205 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Re10.01647 (9)0.00987 (6)0.01285 (8)0.00079 (7)0.00087 (6)0.00059 (7)
Cs10.01357 (13)0.01527 (11)0.01578 (13)0.00073 (10)0.00064 (10)0.00321 (9)
Cl30.0155 (5)0.0164 (4)0.0144 (5)0.0010 (4)0.0032 (4)0.0007 (4)
Cl10.0131 (5)0.0202 (5)0.0143 (5)0.0020 (4)0.0018 (4)0.0007 (4)
Cl20.0141 (5)0.0126 (4)0.0125 (5)0.0007 (4)0.0017 (4)0.0015 (3)
Cl40.0270 (6)0.0159 (4)0.0141 (5)0.0044 (4)0.0007 (4)0.0019 (4)
O10.0220 (16)0.0162 (14)0.0256 (17)0.0044 (11)0.0017 (14)0.0023 (12)
O20.0315 (17)0.0149 (13)0.0148 (15)0.0013 (12)0.0035 (13)0.0016 (11)
Geometric parameters (Å, º) top
Re1—O11.695 (3)Cs1—Cl1iii3.6013 (18)
Re1—O21.704 (3)Cs1—Cl2ii3.4357 (19)
Re1—Cl12.4728 (14)Cs1—Cl23.4761 (19)
Re1—Cl22.4710 (12)Cs1—Cl2iii3.5847 (15)
Re1—Cl32.3299 (13)Cs1—Cl3iii3.5584 (16)
Re1—Cl42.3131 (14)Cs1—Cl3iv3.5751 (17)
Cs1—O13.508 (3)Cs1—Cl4ii3.6662 (16)
Cs1—Cl1i3.5082 (16)Cs1—Cl4v3.7314 (16)
Cs1—Cl1ii3.5331 (18)Cs1—Cs1vi4.856 (2)
O1—Re1—O2103.18 (13)Cl4—Re1—Cl284.97 (4)
O1—Re1—Cl495.05 (10)Cl3—Re1—Cl284.24 (5)
O2—Re1—Cl495.40 (10)O1—Re1—Cl1168.60 (9)
O1—Re1—Cl393.54 (10)O2—Re1—Cl188.20 (10)
O2—Re1—Cl393.48 (10)Cl4—Re1—Cl184.37 (5)
Cl4—Re1—Cl3165.92 (3)Cl3—Re1—Cl185.00 (5)
O1—Re1—Cl287.74 (9)Cl2—Re1—Cl180.86 (4)
O2—Re1—Cl2168.98 (9)
Symmetry codes: (i) x1, y+3/2, z+1/2; (ii) x1, y, z; (iii) x+1, y+2, z+1; (iv) x, y+3/2, z+1/2; (v) x+1, y+1/2, z+3/2; (vi) x, y+2, z+1.

Experimental details

Crystal data
Chemical formulaCs[ReCl4O2]
Mr492.91
Crystal system, space groupMonoclinic, P21/c
Temperature (K)110
a, b, c (Å)6.609 (3), 10.322 (5), 11.714 (5)
β (°) 92.04 (5)
V3)798.6 (6)
Z4
Radiation typeMo Kα
µ (mm1)20.98
Crystal size (mm)0.11 × 0.11 × 0.07
Data collection
DiffractometerOxford Diffraction XcaliburPX CCD
diffractometer
Absorption correctionAnalytical
(ABSPACK and analytical correction; Oxford Diffraction, 2006)
Tmin, Tmax0.164, 0.296
No. of measured, independent and
observed [I > 2σ(I)] reflections
14688, 4462, 2402
Rint0.057
(sin θ/λ)max1)0.941
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.034, 0.77
No. of reflections4462
No. of parameters73
Δρmax, Δρmin (e Å3)1.52, 1.59

Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis RED (Oxford Diffraction, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Bruker, 1997) and DIAMOND (Brandenburg & Putz, 2005).

Selected geometric parameters (Å, º) top
Re1—O11.695 (3)Cs1—Cl1iii3.6013 (18)
Re1—O21.704 (3)Cs1—Cl2ii3.4357 (19)
Re1—Cl12.4728 (14)Cs1—Cl23.4761 (19)
Re1—Cl22.4710 (12)Cs1—Cl2iii3.5847 (15)
Re1—Cl32.3299 (13)Cs1—Cl3iii3.5584 (16)
Re1—Cl42.3131 (14)Cs1—Cl3iv3.5751 (17)
Cs1—O13.508 (3)Cs1—Cl4ii3.6662 (16)
Cs1—Cl1i3.5082 (16)Cs1—Cl4v3.7314 (16)
Cs1—Cl1ii3.5331 (18)Cs1—Cs1vi4.856 (2)
O1—Re1—O2103.18 (13)Cl4—Re1—Cl284.97 (4)
O1—Re1—Cl495.05 (10)Cl3—Re1—Cl284.24 (5)
O2—Re1—Cl495.40 (10)O1—Re1—Cl1168.60 (9)
O1—Re1—Cl393.54 (10)O2—Re1—Cl188.20 (10)
O2—Re1—Cl393.48 (10)Cl4—Re1—Cl184.37 (5)
Cl4—Re1—Cl3165.92 (3)Cl3—Re1—Cl185.00 (5)
O1—Re1—Cl287.74 (9)Cl2—Re1—Cl180.86 (4)
O2—Re1—Cl2168.98 (9)
Symmetry codes: (i) x1, y+3/2, z+1/2; (ii) x1, y, z; (iii) x+1, y+2, z+1; (iv) x, y+3/2, z+1/2; (v) x+1, y+1/2, z+3/2; (vi) x, y+2, z+1.
 

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