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 convent ...

s with the general

chemical formula In chemistry, 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, ...

(''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 (H2CO3), 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 g ...

dianion, the thiocarbonate ions are

trigonal planar In chemistry, trigonal planar is a molecular geometry model with one atom at the center and three atoms at the corners of an equilateral triangle, called peripheral atoms, all in one plane. In an ideal trigonal planar species, all three ligands a ...

, 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, as introduced by Linus Pauling, is defined as the difference between the number of bonds and anti-bonds. The bond order itself is the number of electron pairs (covalent bonds) between two atoms. For example, in diat ...

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 (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 electr ...

s. Thiocarbonates are salts of those ions as well (e.g. sodium dithiocarbonate ). Thiocarbonates are esters of thiose ions as well. They contain trigonal planar divalent

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...

s similar to these anions.

Monothiocarbonate

Monothiocarbonate is the dianion , which has C_2v

symmetry Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definit ...

. 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 ...

thiophosgene Thiophosgene is a red liquid with the formula . 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. Preparation is prepared in a two-step process from carbon ...

or the reaction of base with

carbonyl sulfide Carbonyl sulfide is the chemical compound with the linear formula OCS. It is a colorless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom. Carbonyl sulfide can be conside ...

: : The esters of monothiocarbonic acids are called monothiocarbonates as well (e.g. ''O''-ethyl-''S''-methyl monothiocarbonate ).

Dithiocarbonates

Dithiocarbonate is the dianion , which has C_2v symmetry. It arises from the reaction of aqueous base with

carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non ...

: : Important derivatives of dithiocarbonates are the

xanthate 150px, Sodium salt of ethyl xanthate Xanthate usually refers to a salt with the formula (R = alkyl; M+ = Na+, K+), thus they are the metal-thioate/''O''-esters of dithiocarbonate. The name ''xanthates'' is derived from Ancient Greek ''xanthos'' ...

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 organic 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 chemical element, elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis ...

that consists of two dithiocarbonate groups.

Trithiocarbonates

Trithiocarbonate is the dianion , which has D_3h symmetry. Trithiocarbonate is prepaared by the reaction of

hydrosulfide Bisulfide (or bisulphide in British English) is an inorganic anion with the chemical formula HS− (also written as SH−). It contributes no color to bisulfide salts, and its salts may have a distinctive putrid smell. It is a strong base. Bisul ...

() with carbon disulfide: : The relatively elusive trithiocarbonic acid has been characterized by

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

. Dimethyl trithiocarbonate, , is an ester of trithiocarbonic acid.

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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References

{{Reflist Carbonates Oxyanions Sulfur ions