One-electron transfer processes in the reaction of indium(I) halides with substituted o-quinones

Electron-Transfer Processes in Indium(II) Iodide−o-Quinone Systems

“…The ESR spectrum of the resultant solution, shown in Figure A, clearly contains two components. The more sharply defined of these has the characteristics g = 2.0034, A In = 5.06 G, and A H = 3.40 G, which identify the parent species as an indium(III)−TBSQ • complex B, for which we found g = 2.003 91 at 300 K. This very well resolved spectrum (Figure ) shows a splitting of 0.36 G due to the nine hydrogens of one of the tert -butyl groups, in addition to the splittings due to indium and one of the ring hydrogens of 4.86 and 3.42 G, respectively.…”

“…One of these involves dimerization by In−In bond formation, and disproportionation of this dimer can yield both indium(III) and indium(I)−semiquinone species. These processes, which have been discussed in detail in an earlier paper, explain the ESR spectrum in Figure on the basis that semiquinone derivatives of these two oxidation states are identified. In the competing pathway, [ • In II (SQ • )] may react with a second quinone to give [In III (SQ • ) 2 ] + , which explains the presence of diradical species, with cis ligands in the solution.…”

“…The broader component in the spectrum of Figure A can be interpreted in either of two ways. If it is assumed that the observed features are the visible portion of a broad multiplet centered on g = 2.000, one can extract a hyperfine coupling constant of 10 G, typical of A In for species in which TBSQ •- is bonded to indium(I) . The alternative explanation is that this is a broad signal due to an indium(III) biradical complex in the solution, and this is supported by the frozen-solution spectra (see below).…”

“…The most important general conclusion is that many processes which were earlier believed to involve the concerted transfer of a pair of electrons in fact proceed via successive single-electron transfers. Of particular relevance to the present work are the reactions of 3,5-di- tert -butyl- o -benzoquinone (TBQ) with indium metal, where the product is the indium(I) semiquinone, In(TBSQ), and of this and other o -quinones with indium(I) halides to give XIn(CAT) species (where CAT 2- is the corresponding substituted catecholate) via o -semiquinone complexes. , More recently, we showed that bis(semiquinone) derivatives of indium(III) halides exist in nonaqueous solution and that intramolecular electron-transfer reactions are important in the chemistry of such compounds …”

Four-Coordinate Group-14 Elements in the Formal Oxidation State of Zero – Syntheses, Structures, and Dynamics of [{(CO)5Cr}2Sn(L2)] and Related Species

“…The 3-center-4-π system characterizing the bonding situligands the 13 C signals of the coordinated ligands consistently show the high-field (C a , C e ) and low-field (C b , C c , C d , ation in inidene compounds has a dramatic effect on the NMR shift of the central atom X. It has been found that and C f ) shifts which are known to be characteristic of the coordination of these chelate bases [12] . A theoretical expla-with phosphorus in this position 31 P-NMR shifts range from δ ϭ 900 to δ ϭ 1400, well out of the range of shifts nation of this characteristic pattern of high-and low-field shifts has been put forward [13] .…”