1.2- Dithiole-3-thiones metal complexes

M(dmit)2 complexes (dmit = C3S52- = l,3-dithiole-2-thione-4,5-dithio-late) constitute one of the most important subclasses. The most studied metal complexes are those of group 10 (Ni, Pd, Pt), which possess a square-planar geometry see for instance the molecular structure of the monoanion [Ni(dmit)2], Figure 42.73... 

Cassoux P, Valade L, Kobayashi H, Kobayashi A, Clark RA, Underhill AE (1991) Molecular metals and superconductors derived from metal complexes of l,3-dithiol-2-thione-4, 5-dithiolate (dmit). Coord Chem Rev 110 115-160... 

Another very important group of organic acceptors employed as components for organic metals during the last decade is presented by dithiolene metal complexes [e.g., l,3-dithiole-2-thione-4,5-dithiolate (dmit) ligand and... 

The other most widely studied families of dithiolene complexes are metal complexes of dmit, [M(dmit)2] (dmit = l,3-dithiole-2-thione-... 

Ethylenedithio-l,3-dithiole-2-thione (C5H4S5) (L38) is well known as an electron donor (113,114). It is also a derivative of dmit and has a structure similar to half of. The structure determination of its metal complexes has demonstrated the unique coordination versatility of L38 (Table III). It can act as a monodentate, bidentate, or even... 

Consequently, we will centre our attention on the main type of acceptors according to their different molecular nature. Thus, we will focus on derivatives of the parent molecules TCNQ, dicyano-p-quinonediimine (DCNQI), other polycyano derivatives, dithiolene metal complexes (l,3-dithioIe-2-thione-4,5-dithiolate, dmit) and some interesting cases in the emerging chemistry of fullerene [13] derivatives as shown in Figure 1.1. 

Formation of Metal Complexes. 1,3,4-Thiadiazole-2,5-dithiol, a potential analytical reagent for the detection and determination of cations, forms complex salts with Cu , Zn", Ag, Cd , T1 , Pb , Pd°, and Pt°. The Cu , Ag , and TP complexes are linear those of the other ions are tetrahedral. Bonding occurs through the thione- or thiol-sulphur, except in the Pd° and Pt° complexes, where it involves the nitrogen. The complexes of Ru ", Ru", Rh , Pd, Ir , and Pt were similarly studied. ... 

The structure of [Mo3S4(dmit)3] (dmit=l,3-dithiole-2-thione-4,5-dithiolate) represents one of the rare examples of M3S4 clusters where each metal atom appears as pentacoordinate instead of its more common type-I structure octahedral environment [39]. Complexes [M3Q4(dmit)3] (M = Mo, W Q = S, Se) degrade in air with an almost quantitative yield and afford a series of M(V) dimers of formula [M202(//-Q)2(dmit)2] where the oxygen atoms are in a syn configuration. 

Ethylenediaminetetraacetic acid, analogs, complexes of, 3 277 chelation by, 3 276-277 cobalt complex of, 3 281 complexes, 3 277-278 formation constant of, 3 273-274 -nickel, 3 17-18 stability of, 3 266-267 reaction with metal ions, 3 62 Ethylene dibromide, irradiation of, 5 196 4,5-Ethylenedithio-1,3-dithiole-2-thione based supramolecular complexes, 46 200-204 Ethylene glycol, 32 4... 

Bulk crystalline radical ion salts and electron donor-electron acceptor charge transfer complexes have been shown to have room temperature d.c. conductivities up to 500 Scm-1 [457, 720, 721]. Tetrathiafiilvalene (TTF), tetraselenoful-valene (TST), and bis-ethyldithiotetrathiafulvalene (BEDT-TTF) have been the most commonly used electron donors, while tetracyano p-quinodimethane (TCNQ) and nickel 4,5-dimercapto-l,3-dithiol-2-thione Ni(dmit)2 have been the most commonly utilized electron acceptors (see Table 8). Metallic behavior in charge transfer complexes is believed to originate in the facile electron movements in the partially filled bands and in the interaction of the electrons with the vibrations of the atomic lattice (phonons). Lowering the temperature causes fewer lattice vibrations and increases the intermolecular orbital overlap and, hence, the conductivity. The good correlation obtained between the position of the maximum of the charge transfer absorption band (proportional to... 

Several complexes between tin(rv) centers and the l,3-dithiole-2-thione-4,5-dithiolato or l,3-dithiole-2-one-4,5-dithiolato ligands have been prepared by Wardel s group by methathesis reactions involving addition, elimination, and substitution at the metal atom (Scheme 5) C1998POL4475, 1999JOM140>. 

Dimercapto-l,3-dithiole-2-thione (dmit, 46) and 4,5-dihydro-l,4-dithiin-2,3-dithiolate (dddt, 47) ligands can be reacted with transition metal ions to give M(dmit)2 and M(dddt)2 complexes (M = Pt, Pd, Ni, and Au) [91]. The M(dmit)2 and M(dddt)2 anions, like BEDT-TTF, have numerous peripheral sulfur atoms and are planar. Additionally, they have variable redox potentials that can be adjusted through the metal that is selected. 

In the previous reviewing periods (CHEC(1984), CHEC-II(1996)) theoretical methods were applied in order to understand certain chemical and physical properties of 1,3-dithiole compounds, especially 1,3-dithiolylium ions, 1,3-dithiol-2-one and l,3-dithiole-2-thione. Since 1995, theoretical methods have been applied, mainly to a particular class of compounds, TTFs, which as electron donors easily form charge-transfer (CT) complexes. These complexes show a wide variety of electronic behaviors leading to semiconductor, metal-like, or superconductor properties. 

A wide range of structurally diverse compounds can activate the ARE. Classes of xenobiotics that can stimulate ARE-driven transcription include large planar compounds such as flavonoids and phenolic antioxidants (1), thiol-containing compounds such as isothiocyanates (22,23) and l,2-dithiole-3-thiones (24), heavy metals (25), and heme complexes (26,27). Table 1 shows classes and examples of xenobiotics that are known to stimulate ARE-driven transcription. 

Complex formation between metals and l,2-dithiole-3-thiones has long been known. The mercury(II) complex is often used for purification of 1,2-dithiole-3-thiones.1... 

The stability constants of Ag(I) complexes with a series of l,2-dithiole-3-thiones have been measured in order to obtain quantitative data concerning the complexing ability of the thiones.96 In most cases kinetic measurements involving rates of methylation provide a better method.97 l,2-Dithiole-3-thiones have been used as analytical reagents for metals without further studies of the structure of the complexes formed (cf. Section V). 

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