Stable Salts of the Tellurocyanate Ion.

A fundamental in situ IR spectroelectrochemical study of the electrical polarization of nickel, copper and gold electrodes in the presence of the unstable tellurocyanate ion in DMSO and DMF solutions

“…8,9 This inherent chemical instability has precluded in the past 8 the isolation of such stable salts as potassium tellurocyanate, for instance. The cause of this decomposition is not due to water traces, but due to the destabilisation of the tellurocyanate ion when coming into contact with highly polarizing cations.…”

“…An infrared (IR) spectrum of the pale yellow solution in DMF or DMSO featured a peak at 2079 cm À1 due to the TeCN À ion. 9 The yellow solution was stored under OFN until required. The concentration of TeCN À produced was assumed to be 0.05 mol L À1 based on the amount of KCN added.…”

“…1 This was found to be of use in inhibiting poisoning and accumulation caused by adsorbed CO in systems where formic acid was being oxidised, particularly at intermediate coverages of the adatom. 8 Austad et al 9 isolated pure tetraphenylarsonium tellurocyanate, aer the reaction of tetraphenylarsonium cyanide and tellurium powder in acetonitrile solution. 4 Broadening the knowledge base of electrochemical processes involving tellurium based species is hence valuable in understanding their electrochemical behaviour, especially if the traditional voltammetry techniques used can be combined with a spectroscopic method (e.g.…”

“…Although the TeCN À ion is relatively stable in DMF or acetone, the addition of water will instantly cause decomposition to elemental Te and a CN À ion. 8 Austad et al 9 isolated pure tetraphenylarsonium tellurocyanate, aer the reaction of tetraphenylarsonium cyanide and tellurium powder in acetonitrile solution. It was demonstrated that the tetraphenylarsonium salt of tellurocyanate was reasonably stable during storage as long as no solvent traces were le on the pale yellow crystals.…”

“…5,6 These studies indicated that complex ion species arose from the interaction of electrogenerated Ni(II) and Au(I) ions with the NCO À , NCS À and NCSe À ions in the electrolyte. As the TeCN À ion is fortuitously stable when prepared in dry DMSO and DMF solvents, it was decided to extend the previously reported work 8,9,11 and study by SNIF-TIRS Ni, Cu and Au electrodes electrically polarized in the presence of the TeCN À ion to (1) provide information in an area where there is a complete dearth of previous scientic investigation and also (2) to compare the electrochemistry of the TeCN À ion with that of its structurally related, more stable, analogue ions. It was also of interest to investigate whether the electrochemical behaviour of the TeCN À ion, as reported by Cauquis et al, 14 would also occur on these metal electrodes and whether intermediate species such as [TeCN]…”