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Thiocarbonate describes a family of
anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
s with the general
chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...
(''x'' = 0, 1, or 2): *for ''x'' = 2 it is monothiocarbonate ion *for ''x'' = 1 it is dithiocarbonate ion *for ''x'' = 0 it is trithiocarbonate ion Like the
carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...
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 In chemistry, bond order is a formal measure of the multiplicity of a covalent bond between two atoms. As introduced by Gerhard Herzberg, building off of work by R. S. Mulliken and Friedrich Hund, bond order is defined as the difference between t ...
between C and S or O is . The state of protonation is usually not specified. These anions are good
nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...
s and good
ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
s. Thiocarbonates refer to
salts In chemistry, a salt or ionic compound is a chemical compound consisting of an assembly of positively charged ions ( cations) and negatively charged ions (anions), which results in a compound with no net electric charge (electrically neutral). ...
of those ions as well (e.g. potassium trithiocarbonate, ). Thiocarbonates refer to
ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
s of those ions as well (e.g. dimethyl trithiocarbonate, ). They contain trigonal planar divalent
functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...
s similar to these anions (''x'' = 0, 1, or 2, R is
organyl group In organic and organometallic chemistry, an organyl group (commonly denoted by the letter " R") is an organic substituent with one (sometimes more) free valence electron(s) at a carbon atom.. The term is often used in chemical patent literatur ...
). Esters with the formula are also called
xanthate A xanthate is a Salt (chemistry), salt or ester of a xanthic acid. The formula of the salt of xanthic acid is (where R is organyl group and M is usually Sodium, Na or Potassium, K). Xanthate also refers to the anion . The formula of a xanthic a ...
s, while esters with the formula are also called thioxanthates. Thiocarbonates also refer to salts of organyl thiocarbonate ions (e.g.
sodium ethyl xanthate Sodium ethyl xanthate (SEX) is an organosulfur compound with the chemical formula . It is a pale yellow powder, which is usually obtained as the dihydrate. Sodium ethyl xanthate is used in the mining industry as a Froth flotation, flotation agent. ...
or SEX, ). They contain anions (''x'' = 0, 1, or 2, R is
organyl group In organic and organometallic chemistry, an organyl group (commonly denoted by the letter " R") is an organic substituent with one (sometimes more) free valence electron(s) at a carbon atom.. The term is often used in chemical patent literatur ...
). Anions with the formula , and their salts, are also called
xanthate A xanthate is a Salt (chemistry), salt or ester of a xanthic acid. The formula of the salt of xanthic acid is (where R is organyl group and M is usually Sodium, Na or Potassium, K). Xanthate also refers to the anion . The formula of a xanthic a ...
s, while salts with the formula , and their salts, are also called thioxanthates.


Monothiocarbonate

Monothiocarbonate is the dianion , which has C2v
symmetry Symmetry () in everyday life refers to a sense of harmonious and beautiful proportion and balance. In mathematics, the term has a more precise definition and is usually used to refer to an object that is Invariant (mathematics), invariant und ...
. Monothiocarbonate arises by the
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
of thiophosgene or the reaction of base with
carbonyl sulfide Carbonyl sulfide is the chemical compound with the linear formula . It is a colorless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl double bonded to a sulfur atom. Carbonyl sulfide can be considered to ...
: : The esters of monothiocarbonic acids are called monothiocarbonates as well (e.g. ''O''-ethyl-''S''-methyl monothiocarbonate ).


Dithiocarbonates

Dithiocarbonate is the dianion , which has C2v symmetry. It arises from the reaction of aqueous base with
carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is an inorganic compound with the chemical formula and structure . It is also considered as the anhydride of thiocarbonic acid. It is a colorless, flammable, neurotoxic liquid that is used as ...
: : Important derivatives of dithiocarbonates are the
xanthate A xanthate is a Salt (chemistry), salt or ester of a xanthic acid. The formula of the salt of xanthic acid is (where R is organyl group and M is usually Sodium, Na or Potassium, K). Xanthate also refers to the anion . The formula of a xanthic a ...
s (''O''-esters of dithiocarbonates), with the formula . These salts are typically prepared by the reaction of sodium
alkoxide In chemistry, an alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They are written as , where R is the organyl substituent. Alkoxides are strong bases and, whe ...
s with carbon disulfide. Another group of dithiocarbonates have the formula . They are often derived by hydrolysis of the corresponding trithiocarbonates (RS)2CS. One example is tetrathiapentalenedione, a
heterocycle A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...
that consists of two dithiocarbonate groups.


Trithiocarbonates

Trithiocarbonate is the dianion , which has D3h symmetry. Trithiocarbonate is prepared by the reaction of
sodium hydrosulfide Sodium hydrosulfide is the chemical compound with the formula NaSH. This compound is the product of the half-neutralization of hydrogen sulfide () with sodium hydroxide (NaOH). NaSH and sodium sulfide are used industrially, often for similar purp ...
(NaSH) with carbon disulfide: : The relatively elusive trithiocarbonic acid has been characterized by
X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...
.
Ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
s of thiocarbonic acid, such as dimethyl trithiocarbonate () are also called thioxanthate esters. Trithiocarbonate esters inhibit the enzyme carbonic anhydrase.


Perthiocarbonates

Addition of sulfur to trithiocarbonate gives the perthiocarbonate anion , which contains one sulfur–sulfur bond. Perthiocarbonic acid (or tetrathioperoxycarbonic acid / disulfanylmethanedithioic acid / CAS#13074-70-9) has never been obtained in pure form.A Text-book of Inorganic Chemistry, Volume 7, Issue 2, 1931, p. 269
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See also

* Trithiocarbonic acid *
Xanthate A xanthate is a Salt (chemistry), salt or ester of a xanthic acid. The formula of the salt of xanthic acid is (where R is organyl group and M is usually Sodium, Na or Potassium, K). Xanthate also refers to the anion . The formula of a xanthic a ...
* Thioxanthate *
Sodium ethyl xanthate Sodium ethyl xanthate (SEX) is an organosulfur compound with the chemical formula . It is a pale yellow powder, which is usually obtained as the dihydrate. Sodium ethyl xanthate is used in the mining industry as a Froth flotation, flotation agent. ...
(SEX) * Potassium ethyl xanthate (KEX) *
Potassium amyl xanthate Potassium amyl xanthate (/pəˈtæsiəm ˌæmɪl ˈzænθeɪt/) is an organosulfur compound with the chemical formula CH3(CH2)4OCS2K. It is a pale yellow powder with a pungent odor that is soluble in water. It is widely used in the mining industr ...
* Potassium trithiocarbonate * Ethyl xanthic acid


References

{{Reflist Carbonates Oxyanions Sulfur ions