title: Electrochemical/electrospray mass spectrometric studies of I- and SCN- at gold and platinum electrodes: direct detection of (SCN)3-.
abstract: Results on the electrochemistry of I- and SCN- at gold and platinum electrodes using an electrochemical cell coupled to an electrospray mass spectrometer are reported. We demonstrate that our apparatus is capable of these very challenging electrochemical/electrospray experiments and that B(C6H5)4- is a suitable internal standard for negative-ion studies in acetonitrile. With I- at a platinum electrode, we observe well-behaved oxidation to I3-. Experiments on I- at gold electrodes are more complex, showing AuI2- as well as I3-. The AuI2- mass spectrometric ion intensity varies in a complex way throughout the applied electrochemical voltage range studied; we propose that this variation involves the adsorption of I- on the gold electrode surface. In experiments on SCN- from (C4H9)4NSCN at gold electrodes, we observe Au(SCN)2-. Finally, at platinum electrodes, we directly observe (SCN)3-, a species analogous to I3- and (CN)3- that has been previously postulated but unverified. This important finding was confirmed by the isotope pattern and demonstrates the stability of the anion.
authors.affiliation: Department of Chemistry and Biochemistry, Auburn University, Alabama 36849-5312, USA.
authors.forename: Tan
authors.initials: T
authors.lastname: Guo
authors.forename: Lidong
authors.initials: L
authors.lastname: Li
authors.forename: Vince
authors.initials: V
authors.lastname: Cammarata
authors.forename: Andreas
authors.initials: A
authors.lastname: Illies