Thiocarbonate


Thiocarbonate describes a family of anions with the general chemical formula :
  • for x = 2 it is monothiocarbonate ion
  • for x = 1 it is dithiocarbonate ion
  • for x = 0 it is trithiocarbonate ion
Like the carbonate dianion, the thiocarbonate ions are trigonal planar, with carbon atom at the center of triangle, and oxygen and sulfur atoms at the peaks of the triangle. The average bond order between C and S or O is. The state of protonation is usually not specified. These anions are good nucleophiles and good ligands.
Thiocarbonates refer to salts of those ions as well.
Thiocarbonates refer to esters of those ions as well. They contain trigonal planar divalent functional groups similar to these anions. Esters with the formula are also called xanthates, while esters with the formula are also called thioxanthates.
Thiocarbonates also refer to salts of organyl thiocarbonate ions. They contain anions. Anions with the formula, and their salts, are also called xanthates, while salts with the formula, and their salts, are also called thioxanthates.

Monothiocarbonate

Monothiocarbonate is the dianion, which has C2v symmetry. Monothiocarbonate arises by the hydrolysis of thiophosgene or the reaction of base with carbonyl sulfide:
The esters of monothiocarbonic acids are called monothiocarbonates as well.

Dithiocarbonates

Dithiocarbonate is the dianion, which has C2v symmetry. It arises from the reaction of aqueous base with carbon disulfide:
Important derivatives of dithiocarbonates are the xanthates, with the formula. These salts are typically prepared by the reaction of sodium alkoxides with carbon disulfide.
Another group of dithiocarbonates have the formula. They are often derived by hydrolysis of the corresponding trithiocarbonates 2CS. One example is tetrathiapentalenedione, a heterocycle that consists of two dithiocarbonate groups.

Trithiocarbonates

Trithiocarbonate is the dianion, which has D3h symmetry. Trithiocarbonate is prepared by the reaction of sodium hydrosulfide with carbon disulfide:
The relatively elusive trithiocarbonic acid has been characterized by X-ray crystallography.
Esters of thiocarbonic acid, such as dimethyl trithiocarbonate are also called thioxanthate esters. Trithiocarbonate esters inhibit the enzyme carbonic anhydrase.
image:Na2dmit.svg|thumb|right|Sodium 1,3-dithiole-2-thione-4,5-dithiolate abbreviated Na2dmit is one of several cyclic trithiocarbonates.

Perthiocarbonates

Addition of sulfur to trithiocarbonate gives the perthiocarbonate anion, which contains one sulfur–sulfur bond.
Perthiocarbonic acid has never been obtained in pure form.