Quinoxaline-2,3-dithiol

Square planar Ni11 complexes (50a) and (50b) of the quinoxaline-2,3-dithiolate ligand are oxidizable in chemically reversible, electrochemically quasi-reversible processes to yield Ni111 species, also featuring the (dxy)1 configuration.198 Interestingly, the difference in protonation state makes for a 0.20V difference in oxidation potential ((50a) +0.12V (50b) +0.32V vs. SCE), consistent with the less basic S-donors in the thione form. 

The second example refers to oxomolybdenum dithiolate complex [Md O(qdt)2], where qdt stands for quinoxaline-2,3-dithiolate. This complex also manifests thermal valence isomerism. Helton et al. (2001) also explain it with the change of the molybdenum oxidation state ... 

Quinoxaline-2,3-dithiol [1199-03-7] M 194.1, m 345°(dec). Purified by repeated dissolution in alkali and re-pptn by acetic acid. 

Quinoxaline-2,3-dithiol (H2qdto) acts as a monoanionic and a dianionic chelate respectively in the two complexes Ni(Hqdto)2-2DMF (300) and (Et4N)2[Ni(qdto)2]-2H20.2154,2155... 

The great drawback to this reagent is its proneness to oxidation and it is often stored as the zinc complex from which it is released by dissolving in acid or alkali. The analogous quinoxaline-2,3-dithiol has been recommended for the determination of Ni and Co, and 2-mer-captobenzothiazole (28) for cadmium through extraction of its complex into chloroform.52... 

Recently, variable-temperature absorption data were obtained for oxomolybdenum dithiolate complex [MovO(qdt)2]1 here qdt is quinoxaline-2,3-dithiolate. The data clearly reveal the highly thermochromic nature of this compound. The authors (Helton and others 2001) explain the observed thermochromism through a thermally induced intramolecular electron transfer according to Scheme 1-54 ... 

The room temperature solution electronic absorption spectrum of (L-N3) MoO(bdt) is presented in Fig. 6. This spectrum is representative of virtually all (L-A i)MoO(dithiolene) complexes (19, 23) with the possible exception of (L-/Vi)MoO(qdt) (20, 22), where qdt = quinoxaline-2,3-dithiolate, see below. However, the transitions observed for (L-A MoChtdt) (19), where tdt = toluene-1,2-dithiolate, are generally shifted to slightly lower energies relative... 

Photoluminescence from ambient temperature solutions of metal bis(l,2-dithiolenes) is rarely observed, and there have been only a few reports on luminescence of any type from these compounds. In addition to the weak emission (< ) = 10-5) seen for [Pt(mnt)2]2- (A.max = 775 nm), a similarly weak emission is observed for [Pt(qdt)2]2- (qdt = quinoxaline-2,3-dithiolate, 4) but at significantly higher energy (7,max = 606 nm) (58). Both absorption and emission spectra for the latter complex are highly dependent on solution pH, with protonation of one of the qdt nitrogen atoms leading to the shifts shown in... 

MoO( dithiolene)J [dithiolene — toluene-3,4-dithiolate (tdt) (60), benzene-1,2-dithiolate (bdt) (61, 62), and quinoxaline-2,3-dithiolate (qdt) (63)]. The [(L-/V( )MoO(bdt)] complex has been structurally characterized and the metal shown to have a distorted octahedral stereochemistry with fac-coordination of (L-A3)... 

Quinoline-5-sulfonic acid, 8-hydroxy-7-iodo-metal complexes absorptiometry, 549 Quinolinium salts in gravimetry, 535 Quinoxaline-2,3-dithiol metal complexes liquid-liquid extraction, 547... 

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