Rerefinement of the crystal structure of tri­chlorido­sulfonium­(IV) hexa­chlorido­uranate(V), (SCl3)[UCl6]

Deubner, H.L.; Ivlev, S.I.; Kraus, F.

doi:10.1107/S2414314620009608

inorganic compounds

IUCrDATA

ISSN: 2414-3146

Volume 5| Part 7| July 2020| x200960

https://doi.org/10.1107/S2414314620009608

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Rerefinement of the crystal structure of trichloridosulfonium(IV) hexachloridouranate(V), (SCl₃)[UCl₆]

Holger Lars Deubner,^a Sergei I. Ivlev ^a and Florian Kraus ^a ^*

^aAnorganische Chemie, Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
^*Correspondence e-mail: florian.kraus@chemie.uni-marburg.de

Edited by M. Weil, Vienna University of Technology, Austria (Received 23 June 2020; accepted 14 July 2020; online 17 July 2020)

Single crystals of trichloridosulfonium(IV) hexachloridouranate(V) were obtained from the reaction of uranium(IV) chloride with an excess of disulfur dichloride and studied by single-crystal X-ray diffraction. In comparison with the structure model reported previously [Sawodny et al. (1983 ). Z. Anorg. Allg. Chem. 499, 81–88.], the lattice parameters and fractional atomic coordinates were determined to a much higher precision, leading overall to an improved structure model. The ionic compound contains trigonal–pyramidal (SCl₃)⁺ cations and slightly distorted octahedral [UCl₆]⁻ anions. The structure was refined as an inversion twin with a twin ratio of 4.4:1.

Keywords: crystal structure; uranium; disulfur dichloride; ion pair.

CCDC reference: 2010898

Structure description

We explored the reaction of uranium tetrachloride with disulfur dichloride out of curiosity. Moreover, we investigated whether the latter compound could be a potential solvent for uranium halides. During these studies, high-quality single crystals of (SCl₃)[UCl₆] were obtained.

The lattice parameters determined at 100 K from the current single-crystal X-ray structure determination (Table 3) agree with those reported previously [a = 10.668 (10), b = 10.712 (4) c = 11.333 (6) Å at T = 293 K; Sawodny et al., 1983].

Table 3
Experimental details

Crystal data
Chemical formula	(SCl₃)[UCl₆]
M_r	589.14
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	100
a, b, c (Å)	10.534 (2), 10.545 (2), 11.217 (2)
V (Å³)	1246.0 (4)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	15.07
Crystal size (mm)	0.15 × 0.1 × 0.08

Data collection
Diffractometer	Stoe IPDS 2T
Absorption correction	Numerical (X-RED32; Stoe 2016 )
T_min, T_max	0.036, 0.090
No. of measured, independent and observed [I > 2σ(I)] reflections	18340, 3364, 3304
R_int	0.046
(sin θ/λ)_max (Å⁻¹)	0.686

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.043, 1.08
No. of reflections	3364
No. of parameters	101
Δρ_max, Δρ_min (e Å⁻³)	0.53, −1.01
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.186 (6)
Computer programs: X-AREA (Stoe, 2016), SHELXL (Sheldrick, 2015 ), DIAMOND (Brandenburg, 2019 ) and publCIF (Westrip, 2010 ).

The U^V atom is located on Wyckoff position 4 a and has six chloride ligands in its slightly distorted octahedral coordination sphere (Fig. 1). The U—Cl bond lengths range between 2.4869 (16) and 2.5209 (14) Å and are in good agreement with the previously reported values [U—Cl distances = 2.485 (11)–2.531 (10) Å; Sawodny et al., 1983]. A comparison between the U—Cl bond lengths and Cl—U—Cl angles obtained from the current and the previous refinements is collated in Tables 1 and 2, respectively. Similar U—Cl distances are observed: (i) in the crystal structure of the low-temperature modification of UCl₆ where the coordination sphere for the U atom is also distorted octahedral but with slightly shorter U—Cl bonds of 2.4443 (15)–2.4570 (20) Å (at 100 K; Deubner et al., 2019 ) due to the presence of a U^VI atom, and (ii) in Cs₂[UCl₆] with longer U—Cl bonds of 2.621 Å (at 293 K; Schleid et al., 1987 ) due to the presence of an U^IV atom.

Table 1
Selected interatomic distances d (Å) for (SCl₃)[UCl₆] from the current and the previous refinement

Bond	d (current study)	d (Sawodny et al., 1983)
U1—Cl1ⁱⁱ	2.5263 (15)	2.510 (10)
U1—Cl2ⁱⁱⁱ	2.5297 (15)	2.531 (9)
U1—Cl3	2.5151 (16)	2.521 (10)
U1—Cl4	2.4869 (16)	2.485 (11)
U1—Cl5ⁱ	2.5045 (16)	2.499 (10)
U1—Cl6ⁱⁱ	2.5209 (15)	2.511 (9)
S1—Cl7	1.975 (2)	1.955 (14)
S1—Cl8	1.975 (2)	1.973 (13)
S1—Cl9	1.979 (2)	1.959 (13)
Symmetry codes: (i) −x + $[{3\over 2}]$ , −y + 1, z + $[{1\over 2}]$ ; (ii) −x + 2, y − $[{1\over 2}]$ , −z + $[{3\over 2}]$ ; (iii) x + $[{1\over 2}]$ , −y + $[{3\over 2}]$ , −z + 2.

Table 2
Comparison of selected angles φ (°) for (SCl₃)[UCl₆] from the current and the previous refinement

Angle	φ (current study)	φ (Sawodny et al., 1983)
Cl1ⁱⁱ—U1—Cl2ⁱⁱⁱ	89.86 (5)	89.9 (3)
Cl3—U1—Cl6ⁱⁱ	179.02 (6)	179.3 (4)
Cl3—U1—Cl2ⁱⁱⁱ	91.20 (5)	91.8 (4)
Cl3—U1—Cl1ⁱⁱ	89.76 (6)	90.0 (4)
Cl4—U1—Cl2ⁱⁱⁱ	178.87 (6)	179.4 (4)
Cl4—U1—Cl1ⁱⁱ	89.44 (5)	89.6 (4)
Cl4—U1—Cl3	89.69 (6)	88.2 (4)
Cl4—U1—Cl5ⁱ	91.56 (6)	91.3 (4)
Cl4—U1—C6ⁱⁱ	90.83 (6)	91.2 (4)
Cl5ⁱ—U1—Cl1ⁱⁱ	178.95 (6)	179.0 (4)
Cl5ⁱ—U1—Cl6ⁱⁱ	90.89 (5)	90.1 (4)
Cl5ⁱ—U1—Cl2ⁱⁱⁱ	89.14 (5)	89.2 (4)
Cl5ⁱ—U1—Cl3	89.92 (6)	89.5 (4)
Cl6ⁱⁱ—U1—Cl1ⁱⁱ	89.42 (5)	90.4 (4)
Cl6ⁱⁱ—U1—Cl2ⁱⁱⁱ	88.28 (5)	88.7 (3)
Cl7^iv—S1—Cl8	102.92 (10)	101.7 (7)
Cl7ⁱ—S1—Cl9	102.93 (10)	103.5 (7)
Cl8—S1—Cl9	102.21 (9)	101.8 (6)
Symmetry codes: (i) −x + $[{3\over 2}]$ , −y + 1, z + $[{1\over 2}]$ ; (ii) −x + 2, y − $[{1\over 2}]$ , −z + $[{3\over 2}]$ ; (iii) x + $[{1\over 2}]$ , −y + $[{3\over 2}]$ , −z + 2; (iv) x − $[{1\over 2}]$ , −y + $[{3\over 2}]$ , −z + 2.

Figure 1
The slightly distorted trigonal–pyramidal [SCl₃]⁺ cation and octahedral [UCl₆]⁻ anion of the title compound. Displacement ellipsoids are shown at the 90% probability level.

The S^IV atom is also located on Wyckoff position 4 a and has three chloride atoms in its trigonal–pyramidal coordination sphere (Fig. 1). The S—Cl bond lengths are virtually the same at 100 K. In comparison, Sawodny et al. (1983) reported slightly shorter S—Cl bond lengths for (SCl₃)[UCl₆] at 293 K (Table 1). Nevertheless, these atomic distances are also in good agreement with those reported for the ionic compound β-[SCl₃][SbCl₆] [1.979 (5) to 1.992 (7) Å at 169 K; Minkwitz et al., 1992 ]. The Cl—S—Cl bond angles in (SCl₃)[UCl₆] resulting from the current and the previous refinements differ slightly (Table 2).

The packing of U and S atoms in the crystal structure of (SCl₃)[UCl₆] is shown in Fig. 2. As can be seen, the U and S atoms are arranged according to a distorted NaCl-type of structure. The overall coordination sphere of the S atom can be regarded as [3 + 3], with the three long S—Cl interactions being 3.0721 (2), 3.160 (2) and 3.287 (2) Å. The corresponding coordination polyhedron is a distorted trigonal antiprism, with the S atom displaced from the center.

Figure 2
Packing of the U and S atoms in the crystal structure of (SCl₃)[UCl₆], showing a distorted NaCl-type arrangement. The unit cell drawn in black can be shifted to the one highlighted in blue to make the relation more easily visible. The idealized blue unit cell shows the deviation of U atoms from F-centering as well as the deviation of the (SCl₃)⁺ entities (Cl atoms not shown) from the octahedral voids.

Synthesis and crystallization

(SCl₃)[UCl₆] was synthesized in a borosilicate Schlenk tube from uranium tetrachloride (35 mg, 0.09 mmol) in disulfur dichloride (3 ml) at 358 K over a period of four months. A selected dark-yellow crystal was chosen for single-crystal X-ray diffraction.

We assume that S₂Cl₂ disproportionates under the applied reaction conditions and that elemental chlorine, sulfur monochloride, as well as the sulfur chlorides S₃Cl₂ and S₃Cl₄ are produced in the chemical equilibria described in equations (1)–(3).

3 S₂Cl₂ → S₃Cl₂ + S₃Cl₄ [equation (1); Spong, 1933 ].

S₃Cl₄ → S₂Cl₂ + SCl₂ [equation (2); Spong, 1933].

S₃Cl₄ → S₃Cl₂ + Cl₂ [equation (3); Spong, 1933].

Chlorine is dissolved in an excess of S₂Cl₂ and may then act as an oxidant oxidizing uranium(IV) chloride to form UCl₅ [equation (4)]. Other chlorine-sulfur species may also be responsible for the oxidation.

2 UCl₄ + Cl₂ → 2 UCl₅ [equation (4); Cordfunke et al., 1982 ].

We further assume that the formed SCl₂ [equation (2)] may disproportionate to S₂Cl₂ and SCl₄ [equation (5)].

3 SCl₂ → S₂Cl₂ + SCl₄ [equation (5); Lowry et al., 1927 ].

Finally, the formation of the title compound may be described by the reaction of the Lewis acid UCl₅ with SCl₄ under abstraction of a chloride ion [equation (6)].

SCl₄ + UCl₅ → (SCl₃)[UCl₆] [equation (6); Sawodny et al., 1983].

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. Atomic coordinates of the previously reported (SCl₃)[UCl₆] structure (Sawodny et al., 1983) were used for refinement. The structure was refined as an inversion twin with a twin ratio of 4.4:1. As a result of the similarity of the a and b lattice parameters, a fourfold twin was also considered; refinement of this twin model led to insignificant twin fractions. R_int for the tetragonal crystal system was above 0.4, ruling out a higher symmetry model.

Structural data

CCDC reference: 2010898

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314620009608/wm4134sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620009608/wm4134Isup2.hkl

checkCIF report

Computing details top

Data collection: X-AREA (Stoe, 2016); cell refinement: X-AREA (Stoe, 2016); data reduction: X-AREA (Stoe, 2016); program(s) used to solve structure: coordinates from an isotypic structure; program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2019); software used to prepare material for publication: publCIF (Westrip, 2010).

Trichloridosulfonium(IV) hexachloridouranate(V) top

Crystal data top

(SCl₃)[UCl₆]	D_x = 3.141 Mg m⁻³
M_r = 589.14	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 23552 reflections
a = 10.534 (2) Å	θ = 3.6–58.9°
b = 10.545 (2) Å	µ = 15.07 mm⁻¹
c = 11.217 (2) Å	T = 100 K
V = 1246.0 (4) Å³	Block, dark yellow
Z = 4	0.15 × 0.1 × 0.08 mm
F(000) = 1044

Data collection top

STOE IPDS 2T diffractometer	3364 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	3304 reflections with I > 2σ(I)
Planar graphite monochromator	R_int = 0.046
Detector resolution: 6.67 pixels mm^-1	θ_max = 29.2°, θ_min = 2.7°
rotation method, ω scans	h = −14→13
Absorption correction: numerical (X-Red32; Stoe 2016)	k = −14→14
T_min = 0.036, T_max = 0.090	l = −15→15
18340 measured reflections

Refinement top

Refinement on F²	Primary atom site location: other
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0148P)² + 3.5607P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.019	(Δ/σ)_max = 0.001
wR(F²) = 0.043	Δρ_max = 0.53 e Å⁻³
S = 1.08	Δρ_min = −1.01 e Å⁻³
3364 reflections	Absolute structure: Refined as an inversion twin
101 parameters	Absolute structure parameter: 0.186 (6)
0 restraints

Special details top

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

Refinement. Refined as a 2-component inversion twin.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
U1	0.97364 (2)	0.42494 (2)	0.98324 (2)	0.01499 (6)
S1	0.42766 (14)	0.54654 (14)	0.91370 (13)	0.0181 (3)
Cl1	0.82355 (14)	0.89033 (16)	0.63247 (14)	0.0239 (3)
Cl2	0.59526 (14)	0.94785 (14)	0.86341 (13)	0.0225 (3)
Cl3	0.93040 (17)	0.62131 (16)	0.86263 (15)	0.0273 (3)
Cl4	0.85717 (15)	0.29644 (17)	0.83292 (15)	0.0258 (3)
Cl5	0.72554 (14)	0.53738 (16)	0.59988 (14)	0.0241 (3)
Cl6	0.97901 (16)	0.72883 (13)	0.39615 (13)	0.0220 (3)
Cl7	0.92843 (16)	0.96521 (16)	0.91059 (14)	0.0250 (3)
Cl8	0.60091 (14)	0.60665 (15)	0.87712 (15)	0.0241 (3)
Cl9	0.32415 (15)	0.69986 (15)	0.88359 (15)	0.0255 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
U1	0.01381 (8)	0.01650 (8)	0.01466 (9)	−0.00076 (7)	−0.00008 (7)	−0.00013 (7)
S1	0.0170 (6)	0.0191 (7)	0.0180 (6)	0.0009 (5)	−0.0012 (5)	0.0006 (5)
Cl1	0.0180 (6)	0.0306 (8)	0.0232 (7)	0.0019 (5)	0.0051 (5)	0.0038 (6)
Cl2	0.0221 (7)	0.0233 (8)	0.0221 (7)	0.0034 (5)	0.0020 (5)	−0.0045 (5)
Cl3	0.0355 (8)	0.0223 (7)	0.0241 (7)	0.0010 (6)	−0.0012 (7)	0.0060 (6)
Cl4	0.0219 (7)	0.0316 (8)	0.0239 (7)	−0.0038 (6)	−0.0057 (6)	−0.0059 (6)
Cl5	0.0170 (6)	0.0342 (8)	0.0211 (7)	0.0039 (6)	−0.0024 (5)	−0.0018 (6)
Cl6	0.0227 (6)	0.0192 (6)	0.0240 (6)	0.0011 (6)	−0.0028 (6)	−0.0027 (5)
Cl7	0.0273 (7)	0.0295 (8)	0.0182 (7)	−0.0015 (6)	−0.0004 (6)	0.0028 (6)
Cl8	0.0179 (6)	0.0283 (8)	0.0262 (7)	−0.0016 (5)	0.0012 (5)	0.0053 (6)
Cl9	0.0240 (7)	0.0243 (7)	0.0280 (8)	0.0073 (6)	−0.0025 (6)	0.0035 (6)

Geometric parameters (Å, º) top

U1—Cl4	2.4869 (16)	U1—Cl2ⁱⁱⁱ	2.5297 (15)
U1—Cl5ⁱ	2.5045 (16)	S1—Cl7^iv	1.975 (2)
U1—Cl3	2.5151 (16)	S1—Cl8	1.975 (2)
U1—Cl6ⁱⁱ	2.5209 (14)	S1—Cl9	1.979 (2)
U1—Cl1ⁱⁱ	2.5263 (15)

Cl4—U1—Cl5ⁱ	91.56 (6)	Cl6ⁱⁱ—U1—Cl1ⁱⁱ	89.42 (5)
Cl4—U1—Cl3	89.69 (6)	Cl4—U1—Cl2ⁱⁱⁱ	178.87 (6)
Cl5ⁱ—U1—Cl3	89.92 (6)	Cl5ⁱ—U1—Cl2ⁱⁱⁱ	89.14 (5)
Cl4—U1—Cl6ⁱⁱ	90.83 (6)	Cl3—U1—Cl2ⁱⁱⁱ	91.20 (5)
Cl5ⁱ—U1—Cl6ⁱⁱ	90.89 (5)	Cl6ⁱⁱ—U1—Cl2ⁱⁱⁱ	88.28 (5)
Cl3—U1—Cl6ⁱⁱ	179.02 (6)	Cl1ⁱⁱ—U1—Cl2ⁱⁱⁱ	89.86 (5)
Cl4—U1—Cl1ⁱⁱ	89.44 (5)	Cl7^iv—S1—Cl8	102.92 (10)
Cl5ⁱ—U1—Cl1ⁱⁱ	178.95 (6)	Cl7^iv—S1—Cl9	102.93 (10)
Cl3—U1—Cl1ⁱⁱ	89.76 (6)	Cl8—S1—Cl9	102.21 (9)

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

Selected interatomic distances d (Å) for (SCl₃)[UCl₆] from the current and the previous refinement top

Bond	d (current study)	d (Sawodny et al., 1983)
U1—Cl1ⁱⁱ	2.5263 (15)	2.510 (10)
U1—Cl2ⁱⁱⁱ	2.5297 (15)	2.531 (9)
U1—Cl3	2.5151 (16)	2.521 (10)
U1—Cl4	2.4869 (16)	2.485 (11)
U1—Cl5ⁱ	2.5045 (16)	2.499 (10)
U1—Cl6ⁱⁱ	2.5209 (15)	2.511 (9)
S1—Cl7	1.975 (2)	1.955 (14)
S1—Cl8	1.975 (2)	1.973 (13)
S1—Cl9	1.979 (2)	1.959 (13)

Symmetry codes: (i) -x + 3/2, -y + 1, z + 1/2; (ii) -x + 2, y - 1/2, -z + 3/2; (iii) x + 1/2, -y + 3/2, -z + 2.

Comparison of selected angles φ (°)for (SCl₃)[UCl₆] from the current and the previous refinement top

Angle	φ (current study)	φ (Sawodny et al., 1983)
Cl1ⁱⁱ—U1—Cl2ⁱⁱⁱ	89.86 (5)	89.9 (3)
Cl3—U1—Cl6ⁱⁱ	179.02 (6)	179.3 (4)
Cl3—U1—Cl2ⁱⁱⁱ	91.20 (5)	91.8 (4)
Cl3—U1—Cl1ⁱⁱ	89.76 (6)	90.0 (4)
Cl4—U1—Cl2ⁱⁱⁱ	178.87 (6)	179.4 (4)
Cl4—U1—Cl1ⁱⁱ	89.44 (5)	89.6 (4)
Cl4—U1—Cl3	89.69 (6)	88.2 (4)
Cl4—U1—Cl5ⁱ	91.56 (6)	91.3 (4)
Cl4—U1—C6ⁱⁱ	90.83 (6)	91.2 (4)
Cl5ⁱ—U1—Cl1ⁱⁱ	178.95 (6)	179.0 (4)
Cl5ⁱ—U1—Cl6ⁱⁱ	90.89 (5)	90.1 (4)
Cl5ⁱ—U1—Cl2ⁱⁱⁱ	89.14 (5)	89.2 (4)
Cl5ⁱ—U1—Cl3	89.92 (6)	89.5 (4)
Cl6ⁱⁱ—U1—Cl1ⁱⁱ	89.42 (5)	90.4 (4)
Cl6ⁱⁱ—U1—Cl2ⁱⁱⁱ	88.28 (5)	88.7 (3)
Cl7^iv—S1—Cl8	102.92 (10)	101.7 (7)
Cl7ⁱ—S1—Cl9	102.93 (10)	103.5 (7)
Cl8—S1—Cl9	102.21 (9)	101.8 (6)

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

Funding information

FK thanks the DFG for very generous funding.

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