Mechanistic Implications of the Assembly of Organic Thiocyanates on Precious Metals

Thiocyanate assembly is shown to be an effective method for assembling thiolate structures on platinum, silver, and gold. The assemblies were studied by infrared reflection spectroscopy and X-ray photoelectron spectroscopy (XPS). Two cyanide species were identified on the surfaces: the first corresponding to adsorbed cyanide and the second to a form commonly seen as an intermediate during cyanide etching of metals. The presence of the second species supports the theory that cyanide is leaving the surface as M(CN) x, resulting in a thiolate monolayer. Comparison of thiocyanate assemblies on evaporated gold and silver to those on template-stripped gold demonstrates the integral role of surface morphology in the expulsion of (CN) ads from the surface of the metals.