Thiocarbonate describes a family of anions with the general chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 CS_3-xO_x^2- (x = 0, 1, or 2). Organic compounds structurally related to these anions are also called thiocarbonates.

Like the carbonate

Carbonate

In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....

 dianion, the thiocarbonates are planar, with carbon at the center. The average bond order

Bond order

Bond order is the number of chemical bonds between a pair of atoms. For example, in diatomic nitrogen N≡N the bond order is 3, while in acetylene H−C≡C−H the bond order between the two carbon atoms is also 3, and the C−H bond order is 1. Bond order gives an indication to the stability of a bond....

 from C to S or O is 1.33. The state of protonation is usually not specified. These anions are good nucleophile

Nucleophile

A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...

s and good ligand

Ligand

In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...

s.

Monothiocarbonate

Monothiocarbonate is the dianion CO₂S^2-, which has C_2v symmetry

Symmetry group

The symmetry group of an object is the group of all isometries under which it is invariant with composition as the operation...

. Monothiocarbonate arises by the hydrolysis of thiophosgene

Thiophosgene

Thiophosgene is a red liquid with the formula CSCl2. It is a molecule with trigonal planar geometry. There are two reactive C–Cl bonds that allow it to be used in diverse organic syntheses.-Synthesis of CSCl2:...

 or the reaction of base with carbonyl sulfide

Carbonyl sulfide

Carbonyl sulfide is the chemical compound with the formula OCS. Commonly written as COS, it is a colourless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom...

:

COS + 2 NaOH → Na₂CO₂S + H₂O

Dithiocarbonates

Dithiocarbonate is the dianion COS₂^2-, which has C_2v symmetry. It arises from the reaction of aqueous base with carbon disulfide

Carbon disulfide

Carbon disulfide is a colorless volatile liquid with the formula CS2. The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non-polar solvent...

:

CS₂ + 2 NaOH → Na₂COS₂ + H₂O

Probably the most important dithiocarbonates are the organic derivatives. The xanthate

Xanthate

Xanthate usually refers to a salt with the formula ROCS2-M+ . The name xanthates is derived from Greek ξανθός , meaning “yellowish, golden”, and indeed most xanthate salts are yellow...

s are organosulfur compounds prepared by the reaction of alkoxide

Alkoxide

An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They can be written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands...

s with carbon disulfide. Charge-neutral organic dithiocarbonates, with the formula (RS)₂CO, are also known, often being derived by hydrolysis of the corresponding organic trithiocarbonates. One example is tetrathiapentalenedione, a heterocycle that consists of two dithiocarbonate groups.

Trithiocabonates

Trithiocarbonate is the dianion CS₃^2-, which has D_3h symmetry. Trithiocarbonate is derived from the reaction of sulfide sources with carbon disulfide:

CS₂ + 2 NaSH

Sodium hydrosulfide

Sodium hydrosulfide is the chemical compound with the formula NaHS. This compound is the product of the half neutralization of hydrogen sulfide with sodium hydroxide. NaHS is a useful reagent for the synthesis of organic and inorganic sulfur compounds. It is a colorless solid that typically smells...

→ Na₂CS₃ + H₂S

Addition of sulfur to trithiocarbonate gives the perthiocarbonate anion CS₄^2-, which contains one sulfur-sulfur bond.