Crystal structure of bis­­(fluoro­sulfato-κO)xenon(II), Xe(SO₃F)₂

Thermally unstable Xe(SO₃F)₂ has been prepared by the reaction of XeF₂ with HSO₃F. Single crystals were obtained from HSO₃F by slow cooling in a sealed tube. The mol­ecular structure is characterized by the Xe atom covalently bonded to two O atoms of two fluoro­sulfate tetra­hedra in an almost linear fashion [O—Xe—O = 179.13 (4)°]. The crystal packing is strongly influenced by inter­molecular van der Waals forces.

1. Chemical context

In 1972, Neil Bartlett published data on the unit cell of Xe(SO₃F)₂ (Wechsberg et al., 1972). As a result of the thermal instability of this compound, no further structural details were given at that time, but ¹⁹F and ¹²⁹Xe NMR spectra were reported subsequently (Gillespie et al., 1974; Schrobilgen et al., 1978). The decomposition of Xe(SO₃F)₂ leads cleanly to Xe and S₂O₆F₂.

2. Structural commentary

Analogous to XeF₂ (Agron et al., 1963), the two-coordinated xenon atom adopts a linear geometry [angle O1—Xe—O4 = 179.13 (4)°]. The mol­ecule has nearly C_i symmetry, with the xenon atom at the pseudo-inversion centre (Fig. 1). This finding is in contrast to earlier reports, where C_s symmetry was discussed based on Raman spectroscopic data (Gillespie & Landa, 1973). The Xe—O bonds are 2.1101 (13) and 2.1225 (13) Å, which is typical for Xe—O single bonds, whereas Xe=O double bonds are considerably shorter with lengths ≃ 1.75 Å. The related compound xenon fluoride fluoro­sulfate, XeF(OSO₂F) (Bartlett et al., 1969, 1972), contains a Xe—O bond that is slightly longer [2.155 (8) Å] than in the title compound, but the Xe—F bond of XeF(OSO₂F) is at 1.940 (8) Å shorter than that in XeF₂ (2.00 Å). For XeF(OSO₂F), partial ionic bonding (XeF⁺·OSO₂F⁻) was discussed. Obviously, both XeF₂ and Xe(SO₃F)₂ have a higher covalent character. The S—O bonds in Xe(SO₃F)₂ involving the O atoms that are also bonded to the xenon atom (S1—O1 and S2—O4) are about 0.1 Å longer than the terminal S—O bonds (Table 1), indicating partial double-bond character.

Table 1
Selected geometric parameters (Å, °)

Xe1—O1	2.1101 (13)	S1—F1	1.5449 (12)
Xe1—O4	2.1225 (13)	S2—O6	1.4141 (13)
S1—O3	1.4103 (13)	S2—O5	1.4150 (14)
S1—O2	1.4092 (14)	S2—O4	1.5237 (13)
S1—O1	1.5334 (13)	S2—F2	1.5483 (12)
O1—Xe1—O4	179.13 (4)

Figure 1 The mol­ecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level.

3. Supra­molecular features

The crystal packing (Fig. 2) is strongly influenced by inter­molecular van der Waals inter­actions to seven oxygen atoms and two fluorine atoms (Table 2). Whereas the xenon atom in XeF₂ exhibits inter­molecular inter­actions to eight fluorine atoms (distance 3.42 Å; Agron et al., 1963), XeF(OSO₂F) has fewer contacts (five contacts to oxygen in the range 3.28–3.49 Å and one contact to fluorine of 3.39 Å; Bartlett et al., 1972).

Table 2
Inter­molecular contacts (Å)

Xe1⋯O2	3.1613 (15)	Xe1⋯F1^iv	3.4551 (17)
Xe1⋯O5	3.1855 (16)	Xe1⋯O3^v	3.4707 (19)
Xe1⋯O2^i	3.1872 (17)	Xe1⋯O5^vi	3.4818 (18)
Xe1⋯O6^ii	3.2317 (19)	Xe1⋯F2^vii	3.5867 (17)
Xe1⋯O6^iii	3.3262 (18)
Symmetry codes: (i) -x, -y+1, -z+2; (ii) ; (iii) ; (iv) x+1, y, z; (v) ; (vi) ; (vii) x-1, y, z.

Figure 2 The crystal packing of the title compound

4. Synthesis and crystallization

550 mg fluoro­sulfuric acid were placed in a 8 mm PFA tube. 170 mg (1 mmol) of XeF₂ were added and the mixture vigorously shaken at room temperature for some minutes until all XeF₂ had dissolved. The PFA tube was evacuated for some seconds to remove HF, then frozen with liquid nitro­gen and sealed. The yellow product (≃ 0.2 ml) was warmed to 273 K and the PFA tube placed in a dewar filled with 273 K ethanol and cooled slowly to 193 K in a freezer. The light-yellow single crystals of Xe(SO₃F)₂ that had formed were deca­nted off and mounted in a cold nitro­gen stream. At 100 K, the crystals are colorless. The compound decomposes rapidly in moist air and can ignite organic materials.

5. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 3.

Table 3
Experimental details

Crystal data
Chemical formula	[Xe(SO3F)2]
Mr	329.42
Crystal system, space group	Monoclinic, P21/n
Temperature (K)	100
a, b, c (Å)	6.706 (3), 13.237 (6), 7.769 (3)
β (°)	96.50 (3)
V (Å^3)	685.2 (5)
Z	4
Radiation type	Mo Kα
μ (mm^−1)	5.66
Crystal size (mm)	0.50 × 0.40 × 0.15
Data collection
Diffractometer	Bruker CCD SMART 2000
Absorption correction	Multi-scan (SADABS; Bruker, 2006)
Tmin, Tmax	0.545, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	11036, 2096, 1978
Rint	0.020
(sin θ/λ)max (Å^−1)	0.716
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.013, 0.033, 1.11
No. of reflections	2096
No. of parameters	101
Δρmax, Δρmin (e Å^−3)	0.56, −0.69
Computer programs: SMART and SAINT (Bruker, 2006), SHELXS97, SHELXL and SHELXTL (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 1999).

Supporting information

Computing details

Data collection: SMART (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Bis(fluorosulfato-κO)xenon(II)

Crystal data

[Xe(SO3F)2]	F(000) = 608
Mr = 329.42	Dx = 3.194 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 999 reflections
a = 6.706 (3) Å	θ = 2.0–21.0°
b = 13.237 (6) Å	µ = 5.66 mm^−1
c = 7.769 (3) Å	T = 100 K
β = 96.50 (3)°	Irregular, colorless
V = 685.2 (5) Å^3	0.50 × 0.40 × 0.15 mm
Z = 4

Data collection

Bruker CCD SMART 2000 diffractometer	2096 independent reflections
Radiation source: fine-focus sealed tube	1978 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
ω scans	θmax = 30.6°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Bruker, 2006)	h = −9→8
Tmin = 0.545, Tmax = 1.000	k = −18→18
11036 measured reflections	l = −11→9

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.013	w = 1/[σ^2(Fo^2) + (0.0151P)^2 + 0.4262P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.033	(Δ/σ)max = 0.002
S = 1.11	Δρmax = 0.56 e Å^−3
2096 reflections	Δρmin = −0.69 e Å^−3
101 parameters	Extinction correction: SHELXL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0244 (5)

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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 (Ų)

	x	y	z	Uiso*/Ueq
Xe1	0.000928 (13)	0.627394 (6)	0.726096 (13)	0.01145 (4)
S1	−0.33404 (6)	0.46260 (3)	0.75371 (5)	0.01295 (8)
S2	0.32649 (6)	0.79932 (3)	0.70775 (5)	0.01265 (8)
O4	0.24243 (18)	0.72199 (8)	0.82568 (16)	0.0155 (2)
F2	0.51324 (16)	0.74159 (8)	0.65972 (16)	0.0227 (2)
O2	−0.22016 (19)	0.45699 (9)	0.91739 (17)	0.0190 (2)
F1	−0.52083 (16)	0.52658 (9)	0.78020 (16)	0.0255 (2)
O6	0.4027 (2)	0.88225 (8)	0.80947 (18)	0.0181 (2)
O5	0.2017 (2)	0.81316 (9)	0.55006 (17)	0.0202 (3)
O3	−0.4069 (2)	0.37545 (9)	0.6629 (2)	0.0218 (3)
O1	−0.23650 (18)	0.53141 (9)	0.62828 (16)	0.0168 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Xe1	0.01151 (6)	0.01094 (6)	0.01174 (7)	−0.00098 (3)	0.00068 (3)	0.00171 (3)
S1	0.01200 (16)	0.01179 (15)	0.0150 (2)	−0.00106 (12)	0.00137 (13)	0.00063 (13)
S2	0.01379 (17)	0.01185 (15)	0.01261 (19)	−0.00147 (12)	0.00274 (13)	−0.00024 (13)
O4	0.0159 (5)	0.0156 (5)	0.0143 (6)	−0.0052 (4)	−0.0010 (4)	0.0026 (4)
F2	0.0194 (5)	0.0234 (5)	0.0268 (6)	0.0023 (4)	0.0093 (4)	−0.0049 (4)
O2	0.0216 (6)	0.0210 (5)	0.0141 (6)	−0.0027 (5)	0.0004 (5)	0.0033 (5)
F1	0.0158 (5)	0.0232 (5)	0.0382 (7)	0.0055 (4)	0.0064 (5)	−0.0005 (5)
O6	0.0221 (6)	0.0147 (5)	0.0181 (7)	−0.0052 (4)	0.0047 (5)	−0.0038 (4)
O5	0.0240 (6)	0.0219 (6)	0.0141 (6)	−0.0038 (5)	−0.0006 (5)	0.0044 (5)
O3	0.0243 (6)	0.0164 (6)	0.0248 (8)	−0.0070 (4)	0.0026 (5)	−0.0041 (5)
O1	0.0167 (5)	0.0191 (5)	0.0139 (6)	−0.0064 (4)	−0.0022 (4)	0.0033 (4)

Geometric parameters (Å, º)

Xe1—O1	2.1101 (13)	S1—F1	1.5449 (12)
Xe1—O4	2.1225 (13)	S2—O6	1.4141 (13)
S1—O3	1.4103 (13)	S2—O5	1.4150 (14)
S1—O2	1.4092 (14)	S2—O4	1.5237 (13)
S1—O1	1.5334 (13)	S2—F2	1.5483 (12)
Xe1···O2	3.1613 (15)	Xe1···F1^iv	3.4551 (17)
Xe1···O5	3.1855 (16)	Xe1···O3^v	3.4707 (19)
Xe1···O2^i	3.1872 (17)	Xe1···O5^vi	3.4818 (18)
Xe1···O6^ii	3.2317 (19)	Xe1···F2^vii	3.5867 (17)
Xe1···O6^iii	3.3262 (18)
O1—Xe1—O4	179.13 (4)	O6—S2—O4	108.69 (8)
O3—S1—O2	122.00 (8)	O5—S2—O4	112.64 (8)
O3—S1—O1	108.46 (8)	O6—S2—F2	105.47 (8)
O2—S1—O1	112.23 (7)	O5—S2—F2	105.68 (8)
O3—S1—F1	105.94 (8)	O4—S2—F2	100.24 (7)
O2—S1—F1	105.86 (8)	S2—O4—Xe1	119.74 (7)
O1—S1—F1	99.77 (7)	S1—O1—Xe1	119.18 (7)
O6—S2—O5	121.62 (8)

Symmetry codes: (i) −x, −y+1, −z+2; (ii) x−1/2, −y+3/2, z−1/2; (iii) −x+1/2, y−1/2, −z+3/2; (iv) x+1, y, z; (v) −x−1/2, y+1/2, −z+3/2; (vi) x−1/2, −y+3/2, z+1/2; (vii) x−1, y, z.