Ethylenedithiolate

A similar utilization of two heteroatoms is illustrated by the reaction of the ethylenedithiol (120) with formic acid in the presence of perchloric acid. 4,5-Diphenyl-l,3-dithiolylium perchlorate (121) was formed in 45% yield (69MI40300). Introduction of a 2-oxo or 2-thioxo substituent as in (123 X = 0, S) is illustrated by the reaction of the disodium salt (122) with phosgene and thiophosgene, respectively (76S489). 

Several complexes of iron with the 1,1-ethenedithiolates have been isolated. These are mainly tris-Fe(III) complexes with the 1,1-dicyano-2,2-ethylenedithiolate ligand (1). Recently, however, Coucouvanis et al. (262) synthesized a new 1,1-dithiolate ligand (XVIII) from the reac-... 

A number of complexes of copper with 1,1-dithiolenes are known they are interesting, inasmuch as they form (1) polynuclear species, e.g., [Cu4(i-mnt)3]2 . Recently, a copper(III) complex of 1,1-dicarboeth-oxy-2-ethylenedithiolate (DED ) was prepared (375) by oxidation of aqueous solutions of K2[Cu(DED)2] with a 10-15% excess of Cu(II) or H202, and of (BzPh3P)2[Cu(DED)2] with I2. The possibility of this system as a model for the Cu "/Cu. system in n-galactose oxidase has been pointed out. Lewis and Miller (113) also prepared M[Cu(S2C CHN02)2] (M = Cu, or Zn) and Cu[Cu S2C C(CN)2 2], and found that they are effective insecticides. 

Acetalization or ketalization with silylated glycols or 1,3-propanediols and the formation of thioketals by use of silylated 1,2-ethylenedithiols and silylated 2-mer-captoethylamines have already been discussed in Sections 5.1.1 and 5.1.5. For cyclizations of ketones such as cyclohexanone or of benzaldehyde dimethyl acetal 121 with co-silyl oxyallyltrimethylsilanes 640 to form unsaturated spiro ethers 642 and substituted tetrahydrofurans such as 647, see also Section 5.1.4. (cf. also the reaction of 654 to give 655 in Section 5.2) Likewise, Sila-Pummerer cyclizations have been discussed in Chapter 8 (Schemes 8.17-8.20). 

The synergy between magnetic interaction and spin crossover has been explored in five-coordinate Fe(III) complexes containing two bidentate cis-l,2-dicyano-l,2-ethylenedithiolates together with a monodentate coordinat-... 

Disilyl selenide, 3 240 Disodium ethylenedithiolate complexes with group VIIB metals, 12 242 Disodium phthalocyanine, preparation and properties of, 7 39... 

Two main synthetic routes are available for the preparation of dithiolenes in the first and most frequently used method, either the free ethylenedithiol or an appropriate salt of the ethylene-dithiolato ligand dianion is reacted with a metal salt to produce anions of the dithiolenes, which may or may not be subsequently oxidized to the neutral species the second one, applied so far only to transition metal dithiolenes, converts vicinal diketones into dithiodiketones and reacts these either with zerovalent metals to form dithiolenes directly or uses metal salts to arrive at cationic species, which are reduced to the neutral dithiolenes either during the reaction or in a subsequent step. 

In the synthesis of the parent dithiolenes, the reaction of the disodium salt of ethylene-cts-dithiolate with metal salts is the only useful method.15 For the preparation of substituted dithiolenes the use of substituted ethylenedithiolates is the most efficient choice. In the synthesis of 1,2-dicyanoethylene-l,2-dithiolato ( mnt ) complexes, it is the only available method.16... 

Three main options, described in Scheme 2, exist for the conversion of dithiodiketones to dithiolenes (i) reaction with a transition metal carbonyl or other reactive zerovalent material (ii) reduction to an ethylenedithiolate and reaction as described above for these species and (iii) reaction with a metal salt to form a cationic dithiolene and reduction of the reaction product to the neutral compounds, whereby a suitable solvent (such as methanol) may serve the function of the reducing agent for in situ generation of the neutral species. 

Because the benzene resonance energy is much higher than that of an isolated double bond, the oxidation of an ethylenedithiolate to the butadiene-like dithione is easier to accomplish than the oxidation of a benzenedithiolate to the corresponding dithio-or /io-benzoquinone there is a difference in stability between the dianionic ligands (44) and (46) relative to the dithioketone forms (45) and (47) derived from them by a two-electron oxidation. 

More recently, this approach was used in the synthesis of 3-(thiazol-2-yl)thieno [3,2-Z>]pyridines 137 from the corresponding ethylenedithiolates 138 (2003MI2). 

Whereas complexes of ethylenedithiolate H2C2S212 are typically prepared by the reductive S-dealkylation of c -H2C2(SCH2Ph)2 (Section II.B), a viable alternative route involves base hydrolysis of l,3-dithiol-2-one, H2C2S2(CO).The parent H2C2S2CO can in turn be prepared on a multigram scale from chloroacetal-dehyde (82). This l,3-dithiol-2-one can be functionalized via deprotonation followed by C-alkylation (72), thus opening the way to a variety of functional dithiolenes (Eq. 7). 

The reduced form can be oxidized by iodine when E j2 < +0.40 V otherwise, stronger oxidants, such as Ni(tfd)2 [tfd = l,2-bis(trifluoro-methyl)ethylenedithiolate] are required. 

SYNS 1,2-DLMERCAPTOETHANE D DITHIOETHYL-ENEGLYCOL DITHIOGLYCOL ETHYLENE DIMERCAPTAN a-ETHYLENE DIMERCAPTAN ETHYLENE DITHIOGLYCOL ETHYLENEDITHIOL ETHYL HYDROPERSULFIDE... 

ETHYLENEDITHIOCYANATE see EJC035 ETHYLENE DITHIOGLYCOL see EEBOOO ETHYLENEDITHIOL see EEBOOO... 

Formigue and coworkers have successfully prepared asymmetrically substituted dithiolenes such as edt-CN (edt-CN = 2-cyano-l,2-ethylenedithiolate), tfadt and their square-planar nickel (49 and 50) and gold complexes . Both cis and trails isomers coexist and interconvert in solutions, while in the solid state the trails form is more commonly... 

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