Chemical interactions of pyridine and cyanide with silver

From a quantitative determination of pyridine and cyanide adsorbed on a silver electrode, by a radiochemical technique, we have shown that the two adsorbate - silver systems are different. After a dissolution - redeposition electrochemical cycle the quantity of pyridine adsorbed depends on the charge transfer. For low charge transfer (<50 mC cm^?2) the quantity increases from three to nine monolayers and depends on the nature of the supporting electrolyte, which suggests the formation of new bonds between pyridine, Ag and the anion of the supporting electrolyte. For high charge transfers the quantity of pyridine increases, the rate of increase depending on the supporting electrolyte (KI>KCl>KClO₄); in our opinion this is due to a trapping of pyridine in the salt formed between the support electrolyte anion and silver. The quantity of pyridine adsorbed at the silver electrode which can be as large as 100 equivalent monolayers can explain part of the enhancement of the Raman signal observed for this system.After a dissolution - redeposition electrochemical cycle the quantity of cyanide adsorbed remains constant, the cyanide - silver system is reversible and the Raman enhancement observed at the rest potential, is due only to Ag-CN interactions.