Thiocarbonate

Thiocarbonate describes a family of anions with the general chemical formula CS3−xO2−x (x = 0, 1, or 2). Organic compounds structurally related to these anions are also called thiocarbonates. Thiocarbonate describes a family of anions with the general chemical formula CS3−xO2−x (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 1⁄3. The state of protonation is usually not specified. These anions are good nucleophiles and good ligands. Monothiocarbonate is the dianion CO2S2−, which has C2v symmetry. Monothiocarbonate arises by the hydrolysis of thiophosgene or the reaction of base with carbonyl sulfide: Dithiocarbonate is the dianion COS2−2, which has C2v symmetry. It arises from the reaction of aqueous base with carbon disulfide: Important derivatives dithiocarbonates are the xanthates, 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. 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 derived from the reaction of sulfide sources with carbon disulfide: Addition of sulfur to trithiocarbonate gives the perthiocarbonate anion CS2−4, which contains one sulfur–sulfur bond.Perthiocarbonic acid (or tetrathiocarbonic acid, CAS#13074-70-9) has never been synthesized in the pure form but only as a dark brown solution.