Alkene dithiolates

Also significant are the alkene dithiolate derivatives such as (73) and (74), prepared according to equations (67) and (68).544,545... 

Generally, unsaturated compounds, eg, alkenes and natural fats and their derivatives, are much more reactive toward sulfur than alkanes. Sulfur reacts with unsaturated compounds at temperatures of 120—215°C, forming products that are usually dark and often viscous cross-linked mixtures of dithiole-3-thiones (eq. 4) (2) and sulfides (Table 1) (3). 

Platinum blue formation, 2,265 Platinum complexes, S, 351-500 acetylacetone reactions, 2,380 acetylides reactions, 5,402 alcohols, 5,465 alkene-1,2-dithiolates optica] recording systems, 6,126 alkenes, 5,403 bonding, 5,403... 

A hydroxy and an arylthio group can be added to a double bond by treatment with an aryl disulfide and lead tetraacetate in the presence of trifluoroacetic acid." Manganese and copper acetates have been used instead of Pb(OAc)4. ° Addition of the groups OH and RSO has been achieved by treatment of alkenes with O2 and a thiol (RSH)." Two RS groups were added, to give vie- dithiols, by treatment of the alkene with a disulfide RSSR and Bp3-etherate."° This reaction has been carried... 

Dithiolate ligands are of interest in biological and materials chemistry, and zinc polysulfido complexes can effect the dehydrogenative conversion of alkenes into dithiolates (Scheme 2). 

The meso-ionic l,3-dithiol-4-ones (134) participate - in 1,3-dipolar cycloaddition reactions giving adducts of the general type 136. They show a remarkable degree of reactivity toward simple alkenes including tetramethylethylene, cyclopentene, norbomene, and norbor-nadiene as well as toward the more reactive 1,3-dipolarophilic olefins dimethyl maleate, dimethyl fumarate, methyl cinnamate, diben-zoylethylene, A -phenylmaleimide, and acenaphthylene. Alkynes such as dimethyl acetylenedicarboxylate also add to meso-ionic 1,3-dithiol-4-ones (134), but the intermediate cycloadducts are not isolable they eliminate carbonyl sulfide and yield thiophenes (137) directly. - ... 

This reaction is based on a stoichiometric reaction of multifunctional olefins (enes) with thiols. The addition reaction can be initiated thermally, pho-tochemically, and by electron beam and radical or ionic mechanism. Thiyl radicals can be generated by the reaction of an excited carbonyl compound (usually in its triplet state) with a thiol or via radicals, such as benzoyl radicals from a type I photoinitiator, reacting with the thiol. The thiyl radicals add to olefins, and this is the basis of the polymerization process. The addition of a dithiol to a diolefin yields linear polymer, higher-functionality thiols and alkenes form cross-linked systems. 

Transition metal complexes of unsaturated 1,2-dithiolates (metal dithiolenes) have attracted much attention because of their interesting structural and redox properties.169 Molybdenum dithiolene complexes have featured prominently170 in these studies and have special significance following the suggestion171,172 that the molybdenum-containing cofactor of the oxomolybdoen-zymes (Section 36.6.7) incorporates a molybdenum complex of an unsymmetrically substituted alkene-1,2-dithiolate. 

Aromatic dithiols are stable and can be stored as such. 9,10-Phenanthrenedithiol, for example, is a crystalline (m.p. 134 °C), colorless and odorless solid.23 Other dithiols (such as H2bdt and H2tdt) are commercially available. Dithiols of aliphatic alkenes are prone to decomposition and polymerization.17 They are best converted into alkali metal salts or salts of organic cations such as the tetrabutylammonium ion. These salts usually have a considerable shelf life. 

Another patent describes an advantage for a light-absorbing layer that contains a platinum complex of an alkene-l,2-dithiolate (1,2-dithiolene) such as (124) because of an inherently greater volatility.257... 

Synthesis of 1,3,2-dithiazoles has been the most extensively studied. Various structural types of these compounds have been synthesized in 1990s from raV-dithiols, bis(sulfenylchlorides), and alkynes <1996CHEC-II(4)433>. Much attention has been paid to the preparation of stable 1,3,2-dithiazolyl radicals and, especially, cations. The synthetic potential of 1,3,2-oxathiazoles and 1,3,2-dioxazoles is restricted by several uncommon procedures including nitrosation of thiolcarboxylic acids and photochemical addition of nitrobenzene to alkenes <1996CHEC-II(4)433>. 

For alkanes, alkenes and their aryl derivatives, direct sulfurization gives thiones (3b). Typical examples are the preparation of 4-methyl- (10), 5-(4-methoxyphenyl)- (129) and 4-phenyl-l,2-dithiole-3-thiones (71) and benzo-l,2-dithiole-3-thione (77b) (Scheme 22) (B-66MI43100). 

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