Carbon dichalcogenide

Carbon dichalcogenides are chemical compounds of carbon and chalcogen elements. They have the general chemical formula CZ₂, where Z = O, S, Se, Te.^[1][2]

This includes:

• Carbon dioxide, CO₂
• Carbon disulfide, CS₂
• Carbon diselenide, CSe₂
• Carbonyl sulfide, OCS
• Carbonyl selenide, OCSe
• Thiocarbonyl selenide, SCSe
• Thiocarbonyl telluride, SCTe^[1]

Stability

Double bonds between carbon and chalcogen elements, C=Z, become weaker the heavier the chalcogen, Z. This trend means carbon dichalcogenide monomers are less stable and more susceptible to polymerisation as Z changes from O to Te. For example, CO₂ is stable, CS₂ polymerises under extreme conditions, CSe₂ tends to polymerise, CSeTe is unstable and CTe₂ does not exist.^[1] This trend is an example of the double bond rule.

Bonding

In carbon dichalcogenides, C=O bond lengths are around 1.16 Å, C=S around 1.56 Å, C=Se around 1.70 Å and C=Te around 1.90 Å.^[3]

Carbon–chalcogen double bond lengths in carbon dichalcogenides, Z=C=Z′

Species	Formula	Z	Z′	Bond	Bond in molecule	Bond length / Å	Method of determination	Reference
Carbon dioxide	CO2	O	O	C=O	O=C=O	1.163	infrared spectroscopy	^[1]^[3]^[4]
Carbonyl sulfide	OCS	O	S	C=O	S=C=O	1.158	microwave spectroscopy	^[5]
Carbonyl selenide	OCSe	O	Se	C=O	Se=C=O	1.159	microwave spectroscopy	^[3]
Carbonyl sulfide	OCS	O	S	C=S	O=C=S	1.560	microwave spectroscopy	^[5]
Carbon disulfide	CS2	S	S	C=S	S=C=S	1.553	infrared spectroscopy	^[5]
Thiocarbonyl selenide	SCSe	S	Se	C=S	Se=C=S	1.553	microwave spectroscopy	^[5]
Thiocarbonyl telluride	SCTe	S	Te	C=S	Te=C=S	1.557	microwave spectroscopy	^[3]^[5]^[6]
Carbonyl selenide	OCSe	O	Se	C=Se	O=C=Se	1.709	microwave spectroscopy	^[5]
Thiocarbonyl selenide	SCSe	S	Se	C=Se	S=C=Se	1.693	microwave spectroscopy	^[5]
Carbon diselenide	CSe2	Se	Se	C=Se	Se=C=Se	1.689	neutron diffraction	^[7]
Thiocarbonyl telluride	SCTe	S	Te	C=Te	S=C=Te	1.904	microwave spectroscopy	^[3]^[5]^[6]

References

1. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 306, 314–319, 754–755. ISBN 978-0-08-037941-8.
2. Housecroft, C. E.; Sharpe, A. G. (2008). Inorganic Chemistry (3rd ed.). Prentice Hall. pp. 409–412, 423–425. ISBN 978-0-13-175553-6.
3. Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. p. 926. ISBN 978-0-19-965763-6.
4. Plyler, Earle K.; Blaine, Lamdin R.; Tidwell, Eugene D. (1955). "Infrared absorption and emission spectra of carbon monoxide in the region from 4 to 6 microns". Journal of Research of the National Bureau of Standards. 55 (4): 183–192. doi:10.6028/jres.055.019.
5. William M. Haynes, ed. (2012). CRC Handbook of Chemistry and Physics (93rd ed.). CRC Press. p. 9–33. ISBN 978-1439880500.
6. Hardy, W. A.; Silvey, G. (1954). "Microwave Spectrum of TeCS and Masses of the Stable Tellurium Isotopes". Phys. Rev. 95 (2): 385–. doi:10.1103/PhysRev.95.385.
7. Powell, B. M.; Torrie, B. H. (1983). "Structure of solid carbon diselenide (CSe₂) at 17.5, 50 and 200K". Acta Crystallogr. C. 39 (8): 3070–3072. doi:10.1107/S0108270183007015.