Dithiocarbamate anions, oxidation

A dinuclear selenide complex anion [Au2(M-Se)2(Se4)2] is the product of the reaction" between [AuCN] and Na2 Ses. Square-planar gold(IIl) complexes are readily formed by a variety of bidentate sulfur-donor ligands such as toluene-1,2-dithiolate, maleonitriledithiolate, and dithiocarbamate. On oxidation with CI2 or Br2, [ Au(S2CNR)2 2] forms Au -Au complexes, which may be oxidized further to an Au complex. 

The kinetics of oxidation of dithiocarbamate anions to thiuram disulfides in 30% aqueous acetone by [Mo(CN)g] , [W(CN)g] , and 10 other substitution-inert metal complexes have also been investigated 61). Dithiocarbamates decompose in acid solution and oxidations were consequently performed only on the anionic forms in the pH range 9-12, at which no change in rate constants was observed. The only exception was that of thiophenol, which, upon reacting with [Mo(CN)g] , showed that the reaction rate contribution due to oxidation of the PhSH form was less than 0.002% that of PhS . All of the dithiocarbamates obeyed a simple second-order rate law. 

In another electrochemically and photochemically important group of Pt-polypyridine complexes [202, 203], an electron-accepting polypyridine ligand is combined with an electron-donating dithiolate dianion or dithiocarbamate anion [Pt (S,S)(N,N)]" n = 0 or 1-I-, respectively. These complexes are oxidized in an irreversible or partly reversible one-electron step and reduced in two successive, reversible one-electron steps between ca -1.5 and -2.4 V. Presumably, both reductions are N,N-localized. 

The utility of thallium(III) salts as oxidants for nonaromatic unsaturated systems is a consequence of the thermal and solvolytic instability of mono-alkylthallium(III) compounds, which in turn is apparently dependent on two major factors, namely, the nature of the associated anion and the structure of the alkyl group. Compounds in which the anion is a good bidentate ligand are moderately stable, for example, alkylthallium dicar-boxylates 74, 75) or bis dithiocarbamates (76). Alkylthallium dihalides, on the other hand, are extremely unstable and generally decompose instantly. Methylthallium diacetate, for example, can readily be prepared by the exchange reaction shown in Eq. (11) it is reasonably stable in the solid state, but decomposes slowly in solution and rapidly on being heated [Eq. (23)]. Treatment with chloride ion results in the immediate formation of methyl chloride and thallium(I) chloride [Eq. (24)] (55). These facts can be accommodated on the basis that the dicarboxylates are dimeric while the... 

Dithioacetic acid derivatives add to 1,4-benzo- or 1,4-naphthoquinones to give, after oxidation of the adduct with silver oxide or chloranil, the quinones 217 and 218 (69LA103). Quinones 218 were prepared also from 2,3-dichloro-1,4-naphthoquinone and salts of dithiocarbamic acids (51JA3459) and those of type 219 by oxidation of the corresponding hydroquinones. From reduction potentials and the semiquinone formation constants, it was concluded that their anion radicals are thermodynamically stable (86CC1489). 

The crystal structure of bis(NN-di-isobutyldithiocarbamato)nickel(ii). [Ni(S2-CNBu 2)2], shows that nickel is approximately square planar and co-ordinated by two symmetric bidentate ligands (Ni—S = 2.20 A) the ligand symmetry approximates to 2- The reduction mechanism of a series of nickel(ii) dithiocarbamates has been investigated in DMSO at the mercury electrode it is claimed to involve a dissociation to a nickel species which is more easily reduced than the nickel(ii) dithiocarbamate. An e.p.r. study of the reversible electrochemical reduction of nickel(ii) diethyldithio-carbamates in the presence of 2,2 -bipyridyl show that a bipy radical anion is formed initially. Ligand alkylation occurs when ao -dibromo-o-xylene is added to bis-(NiV-diethyldithiocarbamato)nickel(ii). The electron-transfer properties of 16 nickel(ii) dithiocarbamate complexes have been studied in acetone at a platinum electrode. Their oxidation is difficult and irreversible the overall process is ... 

The most stable iron(IV) species seem to be those containing dithiocarbamate or related ligands such as the low-spin cationic iron tris (dithiocarbamate) complex obtained by oxidation of the neutral iron(III) parent (the high-spin air-sensitive iron(II) anion is also available by reduction) [100]. 

In addition to the adsorption studies of carbonyl, phosphine oxide, and sulfide adsorbates noted in Ref. 10, the studies of interaction of anionic S donors such as dithiocarbamates [17], anionic S-containing species (MoS and Et2NCS ) [18], thiolates [19], and polysulfides [20] with cadmium chalcogenides have been characterized by Wrighton and coworkers [17-20]. This chapter will focus on surface modification of cadmium chalcogenides with thiols, dithiols, sulfides, and disulfides. 

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