A Spectroelectrochemical Investigation of the Interaction of Gold with Cyano-Containing Ligands

Abstract

Surface-enhanced Raman spectroelectrochemical (SERS) investigations of cyanamide, cyanoacetamide and malononitrile interaction with a roughened gold electrode were undertaken. The reagents were readily adsorbed on the surface and large shifts in the C≡N stretch band were observed on adsorption. The C≡N frequency underwent Stark tuning as the potential was scanned and, at high potentials, bands consistent with an oxidized gold complex were observed. It did not appear that the cyano functional group dissociated from the ligands and, together with the large shift in the C≡N stretch frequency on adsorption, this is indicative of π-type coordination. The 1st and subsequent voltammetric cycles in the malononitrile system showed quite different characteristics, indicative of bonding of only one of the two nitriles of the molecule to the gold surface during the 1st oxidation sweep, followed by bonding of both the nitriles in subsequent sweeps.