Thiocarbonate

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Thiocarbonate describes a family of anions with the general chemical formula CS3-xOx2− (x = 0, 1, or 2). Organic compounds structurally related to these anions are also called thiocarbonates.

Like the carbonate dianion, the thiocarbonates are planar, with carbon at the center. The average bond order from C to S or O is 1.33. The state of protonation is usually not specified. These anions are good nucleophiles and good ligands.[1]

Monothiocarbonate[edit]

Monothiocarbonate is the dianion CO2S2−, which has C2v symmetry. Monothiocarbonate arises by the hydrolysis of thiophosgene or the reaction of base with carbonyl sulfide:

COS + 2 NaOH → Na2CO2S + H2O

Dithiocarbonates[edit]

Dithiocarbonate is the dianion COS22−, which has C2v symmetry. It arises from the reaction of aqueous base with carbon disulfide:

CS2 + 2 NaOH → Na2COS2 + H2O

Probably the most important dithiocarbonates are the organic derivatives. The xanthates are organosulfur compounds prepared by the reaction of alkoxides 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.

Trithiocarbonates[edit]

Trithiocarbonate is the dianion CS32−, which has D3h symmetry. Trithiocarbonate is derived from the reaction of sulfide sources with carbon disulfide:[2]

CS2 + 2 NaSH → Na2CS3 + H2S

Perthiocarbonates[edit]

Addition of sulfur to trithiocarbonate gives the perthiocarbonate anion CS42−, which contains one sulfur-sulfur bond.[3]
Perthiocarbonic acid (or tetrathiocarbonic acid, CAS#13074-70-9[4]) has never been synthesized in the pure form but only as a dark brown solution.[5]

References[edit]

  1. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  2. ^ R. E. Strube (1963). "Trithiocarbodiglycolic Acid". Org. Synth. ; Coll. Vol. 4, p. 967 (a procedure for synthesis of K2CS3
  3. ^ Sodium perthiocarbonate o PubChem
  4. ^ http://www.ebuychem.com/product/13074-70-9.html
  5. ^ http://sulphur.atomistry.com/perthiocarbonic_acid.html