Nickel dithiolene oxidation

Yields are diminished if the filiation is conducted prior to the addition of the metal, indicative of the thermal instability of these dithioamides. Furthermore, the yields are lower when Ni(II) salts are used in place of Ni powder, consistent with the oxidative character of the dithioamide. Nickel dithiolenes of the dithio-oxamides exhibit extraordinary extinction coefficients ( 80,000 dm3 mol em 1 at 1000 nm) (186, 187). 

Indium tin oxide Bi-julodinyl nickel dithiolene Tetra-julodinyl nickel dithiolene Kalium tetracyanoplatinat (German)... 

The mesogenic nickel dithiolenes were found to have reduction potentials (against calomel) of +0.06V and 0.76 V and as such were expected to form charge-transfer complexes with the mesomorphic, substituted tetrathiafulvalene (TTF) derivatives (Figure 89), which had oxidation potentials (also against calomel) of +0.43 V and +0.88 V. 

Fig. 10. Representation of the mechanism of redox driven K + transport using an electron and a cation carrier. (59-Ni°) and (59-Ni ) are the oxidized and reduced form of the electron carrier, the nickel bis-dithiolene complex 59 [] and [K+] are dicyclohexyl-18-crown-6 and its K+ complex. (Cited from Ref. 59>)...

The electron transfer properties of nickel 1,2-dithiolenes Ni(R2C2S2)" have been extensively studied in recent years, but there is still much controversy concerning the nature of the bonding in these complexes. On the basis of a simple VB model neutral and binegative species (87) may be assumed to contain the metal in the oxidation state +2, mononegative species may contain either nickel(II) or nickel (III), and trinegative species are assumed to contain nickel(I). 

The terminology partially reduced and partially oxidized dithiolenes used in this physics-dominated field may be confusing, and a few words to clarify this situation may be needed, (i) The Ni atom in an Ni(mnt)2 complex, in which n — 0, 1, 2 or 3, will have a formal oxidation state of 4 +, 3 +, 2+ or 1 +, respectively, (ii) An Ni(mnt)2- complex with a nonintegral nickel oxidation state, for example 3.5 + in a complex with n - 0.5, can be formally and experimentally derived either from Ni(mnt) by partial reduction or from Ni(nmt)2" by partial oxidation, (iii) A look at the formula of the product will convince the confused reader that the terms partially oxidized and partially reduced are used interchangeably and that they may indeed describe the same complex. 

In one seminal work on dithiolene compounds, Schrauzer and Mayweg (37) considered three possible structures for neutral dithiolene nickel complexes in which the oxidation state of nickel may be Ni(0), Ni(II), or Ni(IV) [Scheme 8 ... 

Redox non-innocent ligands have also been employed in other kinds of processes. For example, a nickel-based system has been used in the purification of ethene gas streams [41]. The two forms (reduced and oxidized) of the dithiolene complex have different affinities for olefin, leading to separation of ethene from gas mixtures (Scheme 14). Intermediate 47 is obtained after electrochemical oxidation of the anionic nickel complex 46. The oxidized complex 47 reacts selectively with ethylene to form the adduct 48, thus the non-olefinic contamination of the multi-component stream... 

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