Sulfur tetrachloride

Sulfur tetrachloride

Names
IUPAC name Sulfur(IV) chloride
Identifiers
CAS Number	13451-08-6
Jmol interactive 3D	Image
InChI InChI=1/Cl4S/c1-5(2,3)4
SMILES ClS(Cl)(Cl)Cl
Properties
Chemical formula	SCl4
Molar mass	173.87
Appearance	White powder
Melting point	−31 °C (−24 °F; 242 K)
Boiling point	−20 °C (−4 °F; 253 K) (decomposes)
Solubility in water	soluble in water
Hazards
R-phrases	R14, R34, R50
S-phrases	(S1/2), S26, S45, S61
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sulfur tetrachloride is an inorganic compound with chemical formula SCl₄. It is an unstable pale yellow solid, decomposing to sulfur dichloride and chlorine at temperatures above 242 K. It is obtained by treating sulfur dichloride with chlorine at 193 K:

$\rm SCl_2 + Cl_2 \xrightarrow{193~K} SCl_4$

Its solid structure is uncertain. It is probably the salt SCl₃⁺Cl⁻, since related salts are known.^[1]

Characteristics

Sulfur tetrachloride is stable in solid state below −30 °C and decomposes to chlorine and sulfur when temperature rises. In solid state, there is a white, finely powdered substance. It melts with simultaneous decomposition above −20 °C.^[2] Sulfur tetrachloride reacts with water, producing hydrogen chloride and sulfur dioxide through the hydrolysis process.^[3]

Gas-phase SCl₄ has a seesaw molecular geometry as evidenced from microwave spectroscopy and electron diffraction.^[4] The liquid has a fluxional trigonal bipyramidal geometry with rapid exchange of the axial and equatorial fluorine atoms on the NMR timescale at room temperature.^[4] For the solid state a structure has been reported consisting of a SCl₄ seesaw geometry^[4] linked in a three-dimensional network by weak S–F interactions, two per molecule.

Reactions

• Decomposition:

$\mathrm{SCl_4\ \xrightarrow{-15~^\circ C}\ SCl_2 + Cl_2 }$

• Reacting with water in air:

$\mathrm{SCl_4 + H_2O \ \xrightarrow{}\ SOCl_2 + 2HCl }$

• Treated with water:

$\mathrm{SCl_4 + 2H_2O \ \xrightarrow{}\ SO_2 + 4HCl }$

• Oxidized by nitric acid:

$\mathrm{SCl_4 + 2HNO_3 + 2H_2O \ \xrightarrow{}\ H_2SO_4 + 2NO_2\uparrow + 4HCl }$

• Reacting with sodium hydroxide:^[5][6][7]

$\mathrm{SCl_4 + 6NaOH \ \xrightarrow{}\ Na_2SO_3 + 4NaCl + 3H_2O }$

References

1. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
2. Georg Brauer: Handbuch der Präparativen Anorganischen Chemie. (German)
3. Holleman-Wiberg, Lehrbuch der Anorganischen Chemie, 101. Auflage, de Gruyter Verlag 1995 ISBN 3-11-012641-9 (German)
4. Goettel, J. T., Kostiuk, N. and Gerken, M. (2013), The Solid-State Structure of SF4: The Final Piece of the Puzzle . Angew. Chem. Int. Ed., 52: 8037–8040. doi:10.1002/anie.201302917
5. Справочник химика / Редкол.: Никольский Б.П. и др.. — 3-е изд., испр. — Л.: Химия, 1971. — Т. 2. — 1168 с. (Russian)
6. Химическая энциклопедия / Редкол.: Кнунянц И.Л. и др.. — М.: Советская энциклопедия, 1995. — Т. 4. — 639 с. — ISBN 978-5-85270-092-6 (Russian)
7. Лидин Р.А. и др. Химические свойства неорганических веществ: Учеб. пособие для вузов. — 3-е изд., испр. — М.: Химия, 2000. — 480 с. — ISBN 5-7245-1163-0 (Russian)