Dithioacids

This type of synthesis, which was investigated by Cook and Heilbron (323) and Takahashi (393, 394) between 1947 and 1953, gives 5-aminothiazoles variously substituted in the 2-position by reacting an aminonitrile with salts and esters of dithioacids, carbon disulfide, carbon oxysulfide, and isothiocyanates under exceptionally mild conditions. 

Thioacids have a most disagreeable odour and slowly decompose in air. Their boiling points are lower than those of the coiTcsponding oxygen counterparts and they are less soluble in water, but soluble in most organic solvents. An important dithioacid is dithiocarbonic acid (HO—CS2H). Whilst the free acid is unknown, many derivatives have been prepared such as potassium xanthate giving a yellow precipitate of copper xanthate with copper salts ... 

Esters of dithioacids often give 1,2,3,4-thiatriazoles in good yield on treatment with sodium azide [Eq. (2)] however, this method is not as general as method 1. Dithiocarbamic and xanthic acids and... 

Addition of dithioacids to electron-deficient monomers (MA, MMA, AN) proceeds by Michael addition to pul sulfur at the unsubslituted end of the double bond.479... 

The chemistry of dithioacid and 1,1-dithiolate complexes. D. Coucouvanis, Prog. Inorg. Chem., 1970,11,233-371 (516). 

The dithioacid family of ligands includes dithiocarbamates (R2N CS2 ), xanthates (RO-CS2 ), thioxanthates (RS CS2 ) and dithiocarboxylates (R CS2 ), which have been described in CCC(1987, Section 47.8.10).1 The ligands are prepared by addition of a suitable nucleophile to the carbon center in CS2, usually in the presence of a base. It has been established for some decades that they bind to Co almost exclusively as bidentate chelates, including S-donors acting as bridging ligands in dinuclear systems. 

Dithioacids have been generated from carbon disulfide with Grignard reagents or alkyl lithium at 0 °C. Subsequent treatment with sulfonamide in situ gives the corresponding both aliphatic as well as aromatic thioamides in 70-90% yields (Scheme 10).31... 

Substituted dithioformate anions as ligands R C(S)S are usually called dithiocarbamates (R = R2N), alkyl and aryl dithiocarbonates or xanthates (R = RO), alkyl and aryl trithiocar-bonates or thioxanthates (R = RS). Dithioacid anions (R = alkyl, aryl) have been rarely used as ligands of nickel(II) because of their instability. Structural properties of selected nickel(II) complexes with substituted dithioformate, dithiolene and related ligands are shown in Table 90. 

Numerous complexes of nickel(II) with phosphorodithioate ligands (also called dithio-phosphates 280 R — R" = 0-alkyl, O-aryl) and dithiophosphinates (280 R = R" = alkyl, aryl) have been reported to date. A few dithiophosphonato complexes (280 R = alkyl, R" = O-alkyl) were also reported. The bis(dialkyldithiophosphato)nickel(II) complexes were obtained as purple diamagnetic compounds by means of the direct synthesis between the appropriate dithioacid (RO)2P(S)SH and a nickel(II) salt, often the acetate hydrate. The dithioacid can be conveniently prepared in situ, by reacting P4Si0 with the appropriate alcohol which sometimes acts by itself as reaction medium. Structural properties of selected nickel(II) complexes are reported in Table 90. 

Reactions of Mo2(02CCH3) with mono- and dithioacid anions produce a... 

A major class of sulfur-containing ligands is obtained by the general reaction of carbon disulfide with various nucleophiles. These ligands can be classified into two categories the uninegative 1,1-dithioacids and the dinegativc 1,1-dithiolates (Fig. 1). 

The 1,1-dithioacids are obtained readily by the addition of uninegativc nucleophiles to CS2 under a variety of experimental conditions. Major types of ligands that have been obtained, which show exciting coordination properties. 

The addition of dinegative nucleophiles to CS2, or at times the deprotonation of the S2 CNHR or S2 CCHR2 dithioacid ligands, gives rise to the dinegative 1,1 -dithiolates. 

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