EXAFS/XANES measurements combined with IR spectroelectrochemistry directly probe in situ the coordination sphere of electrogenerated ions in metal electrode systems so obviating the need to isolate ions unchanged from the electrolyte for analysis.
On page H739, right column, the caption for Figure 1 should be On page H745, Table II On page H747, right column, the caption for Figure 9 should be Electroanal. Chem., 92, 45 (1978).) unless CC License in place (see abstract
Subtractively normalised Fourier transform infrared spectroscopic (SNIFTIRS) studies combined with volammetric and supporting model solution studies have conclusively shown that Au electrodes anodically polarized in DMSO and DMF solutions containing the pseudohalide ions: cyanate, thiocyanate and selenocyanate with tetrabutylammonium perchlorate as supporting electrolyte dissolve to form Au(I) pseudohalide complex ions (i.e. [Au(NCO) 2 ] − , [Au(SCN) 2 ] − and [Au(SeCN) 2 ] − . This work has demonstrated the significance of the Au(I) oxidation state which occurs after applied voltages of +500 mV(AgCl/Ag) in the little characterized electrochemistry of this metal in polar aprotic solvents, DMSO and DMF The Au(I) species observed electrochemically by SNIFTIRS were confirmed by independent preparation in DMSO/DMF containing mixtures of KAuBr 4 and the pseudohalide salt (KOCN/NaSCN/KSeCN) and exploiting fortuitous redox chemistry where Au(I) formed spontaneously. The model solutions examined by transmission FTIR and ESI-MS confirmed the existence of the Au(I) species posited in the SNIFTIRS experiments but additionally revealed other interesting side reactions occurring in the model solutions.
Subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) studies have been performed for the first time on the interaction of the tellurocyanate ion (TeCN À ) with electrically polarised nickel (Ni), copper (Cu) and gold (Au) electrodes in dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) containing tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte. In general, it was conclusively shown that the TeCN À ion decomposes at certain applied potentials on electrically polarized electrochemical cells to form elemental tellurium and cyanide (CN À ) ion. The cause of the decomposition was reasoned to be due to the presence of electrodissolved metal ions from the electrode, which destabilise the TeCN À ion through their polarising power as cations. The severity of the destabilisation was found to increase in the order Au + > Cu + > Ni 2+ , which is in general agreement with the relative polarising power of these metal ions. SNIFTIRS and IR transmission data from model solutions demonstrated that the metal complex ion speciation observed during the polarization experiments therefore arose directly from the interaction of the studied metal electrode with CN À ions released by decomposition, rather than with the TeCN À ion itself. The potential at which the electrochemical decomposition of the TeCN À ion occurred and its rate of decomposition depended on the type of metal electrode used. In general, the instability of the TeCN À ion in electrochemically polarized systems reflects its fundamental chemistry of decomposing in the presence of polarizing cations and that it may be of use as a sensor for these species in an electrochemical setting.
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