Carbon dichalcogenide explained

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

This includes:

• Carbon dioxide,
• Carbon disulfide,
• Carbon diselenide,
• Carbonyl sulfide, OCS
• Carbonyl selenide, OCSe
• Thiocarbonyl selenide, SCSe
• Thiocarbonyl telluride, SCTe

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, is stable, polymerises under extreme conditions, tends to polymerise, CSeTe is unstable and does not exist. 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.^[1]

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	^[2]
Carbonyl sulfide	OCS	O	S	C=O	S=C=O	1.158	microwave spectroscopy	^[3]
Carbonyl selenide	OCSe	O	Se	C=O	Se=C=O	1.159	microwave spectroscopy
Carbonyl sulfide	OCS	O	S	C=S	O=C=S	1.560	microwave spectroscopy
Carbon disulfide		S	S	C=S	S=C=S	1.553	infrared spectroscopy
Thiocarbonyl selenide	SCSe	S	Se	C=S	Se=C=S	1.553	microwave spectroscopy
Thiocarbonyl telluride	SCTe	S	Te	C=S	Te=C=S	1.557	microwave spectroscopy	^[4]
Carbonyl selenide	OCSe	O	Se	C=Se	O=C=Se	1.709	microwave spectroscopy
Thiocarbonyl selenide	SCSe	S	Se	C=Se	S=C=Se	1.693	microwave spectroscopy
Carbon diselenide		Se	Se	C=Se	Se=C=Se	1.689	neutron diffraction	^[5]
Thiocarbonyl telluride	SCTe	S	Te	C=Te	S=C=Te	1.904	microwave spectroscopy

Notes and References

1. Book: A. F. . Wells . Structural Inorganic Chemistry . 5th . 1984 . Oxford University Press . 978-0-19-965763-6 . 926 .
2. Infrared absorption and emission spectra of carbon monoxide in the region from 4 to 6 microns . 183–192 . Earle K. . Plyler . Lamdin R. . Blaine . Eugene D. . Tidwell . Journal of Research of the National Bureau of Standards . 1955 . 55 . 4 . 10.6028/jres.055.019 . free .
3. Book: . 93rd . . 2012 . William M. Haynes . 9–33 . 978-1439880500 .
4. Microwave Spectrum of TeCS and Masses of the Stable Tellurium Isotopes . W. A. . Hardy . G. . Silvey . . 95 . 385– . 1954 . 2 . 10.1103/PhysRev.95.385 .
5. B. M. . Powell . B. H. . Torrie . Structure of solid carbon diselenide (CSe₂) at 17.5, 50 and 200K . 1983 . . 39 . 8 . 3070–3072 . 10.1107/S0108270183007015 .