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Carbon diselenide

Carbon diselenide

Names
IUPAC name Carbon diselenide
Systematic IUPAC name Methanediselenone
Other names Carbon selenide Diselenoxomethane Methanediselone Carbon(IV) selenide
Identifiers
CAS Number	506-80-9 Y
3D model (JSmol)	Interactive image
ChemSpider	61481 Y
ECHA InfoCard	100.007.323
EC Number	208-054-9
PubChem CID	68174
UNII	WD123H448C Y
CompTox Dashboard (EPA)	DTXSID1060138
InChI InChI=1S/CSe2/c2-1-3 Y Key: JNZSJDBNBJWXMZ-UHFFFAOYSA-N Y InChI=1/CSe2/c2-1-3 Key: JNZSJDBNBJWXMZ-UHFFFAOYAM
SMILES [Se]=C=[Se]
Properties
Chemical formula	CSe2
Molar mass	169.953 g·mol−1
Appearance	Yellow liquid
Density	2.6824 g/cm3
Melting point	−43.7 °C (−46.7 °F; 229.5 K)
Boiling point	125.5 °C (257.9 °F; 398.6 K)
Solubility in water	0.054 g/(100 mL)
Solubility	Soluble in CS2, toluene
Dipole moment	0 D
Thermochemistry
Heat capacity (C)	50.32 J/(mol·K) (gas)
Std molar entropy (S⦵298)	263.2 J/(mol·K) (gas)
Std enthalpy of formation (ΔfH⦵298)	219.2 kJ/mol (liquid)
Hazards
Flash point	30 °C (86 °F; 303 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Chemical compound

Carbon diselenide is an inorganic compound with the chemical formula CSe₂. It is a yellow-orange oily liquid with pungent odor. It is the selenium analogue of carbon disulfide (CS₂) and carbon dioxide (CO₂). This light-sensitive compound is insoluble in water and soluble in organic solvents.

Synthesis, structure and reactions[edit]

Carbon diselenide is a linear molecule with D_∞h symmetry. It is produced by reacting selenium powder with dichloromethane vapor near 550 °C.^[1]

2 Se + CH₂Cl₂ → CSe₂ + 2 HCl

It was first reported by Grimm and Metzger, who prepared it by treating hydrogen selenide with carbon tetrachloride in a hot tube.^[2]

Like carbon disulfide, carbon diselenide polymerizes under high pressure. The structure of the polymer is thought to be a head-to-head structure with a backbone in the form of [−C(=Se)−Se−]_n.^[3] The polymer is a semiconductor with a room-temperature conductivity of 50 S/cm.

In addition, carbon diselenide is a precursor to tetraselenafulvalenes,^[4] the selenium analogue of tetrathiafulvalene, which can be further used to synthesize organic conductors and organic superconductors.

Carbon diselenide reacts with secondary amines to give dialkydiselenocarbamates:^[1]

2(CH₃CH₂)₂NH + CSe₂ → [(CH₃CH₂)₂NH+2]((CH₃CH₂)₂N−CSe−2)

Safety[edit]

Carbon diselenide has high vapor pressure. It has a moderate toxicity and presents an inhalation hazard. It may be dangerous due to its easy membrane transport. It decomposes slowly in storage (about 1% per month at –30 °C). When obtained commercially, its cost is high.^[5]

Pure distilled carbon diselenide has an odor very similar to that of carbon disulfide, but mixed with air, it creates extremely offensive odors (corresponding to new, highly toxic reaction products).^[6][7] Its smell forced an evacuation of a nearby village when it was first synthesized in 1936.^[7] Because of the odor, synthetic pathways have been developed to avoid its use.^[8]

References[edit]