Thiocarbonate describes a family of anions with the general chemical formulaCS 3−xO2− x (x = 0, 1, or 2):
for x = 2 it is monothiocarbonate ion CO2S2−
for x = 1 it is dithiocarbonate ion COS2−2
for x = 0 it is trithiocarbonate ion CS2−3
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 4/3. The state of protonation is usually not specified. These anions are good nucleophiles and good ligands.[1][2]
The esters of monothiocarbonic acids are called monothiocarbonates as well (e.g. O-ethyl-S-methyl monothiocarbonate CH3CH2OC(O)SCH3).
Dithiocarbonates
Dithiocarbonate is the dianion COS2−2, which has C2v symmetry. It arises from the reaction of aqueous base with carbon disulfide:
CS2 + 2 NaOH → Na2COS2 + H2O
Important derivatives of dithiocarbonates are the xanthates (O-esters of dithiocarbonates), with the formula ROCS−2. These salts are typically prepared by the reaction of sodium alkoxides with carbon disulfide.
Another group of dithiocarbonates have the formula (RS)2CO.[3] They are often derived by hydrolysis of the corresponding trithiocarbonates (RS)2CS. One example is tetrathiapentalenedione, a heterocycle that consists of two dithiocarbonate groups.
Trithiocarbonate is the dianion CS2−3, which has D3h symmetry. Trithiocarbonate is prepared by the reaction of sodium hydrosulfide (NaSH) with carbon disulfide:[4]
This article uses material from the Wikipedia article Poly(thiocarbonate)s, and is written by contributors.
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