Oxidative adsorption of n-alkanethiolates at mercury. Dependence of adsorption free energy on chain length

Keith J. Stevenson, Melissa Mitchell, Henry S. White

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)

Abstract

The oxidative adsorption of n-alkanethiolates (CncH2nc+1S-, nc = 2-8) at Hg in aqueous solutions containing 0.5 M NaOH is reported. Oxidative adsorption of CncH2nc+1S- is characterized by two voltammetric waves corresponding to the formation of energetically distinct low-density and high-density surface phases of Hg-SCncH2nc+1. The high-density surface phase (9.8 × 10-10 mol/cm2) corresponds to adsorption of ca. one monolayer of CncH2nc+1S-. Electrodeposition of a bulk film of a mercury thiolate complex also occurs at more positive potentials in solutions containing short-chain n-alkanethiolates, nc ≤ 5. The dependence of the adsorption half-wave potential E1/2 on the solution concentration of CncH2nc+1S- indicates that approximately one electron is transferred per adsorbed molecule. The free energy of adsorption ΔGads of CncH2nc+1S- on Hg decreases by ∼1 kcal/mol per nc, reflecting the influence of hydrophobic interactions and intermolecular forces on the thermodynamic stability of the monolayer.

Original languageEnglish
Pages (from-to)1235-1240
Number of pages6
JournalJournal of Physical Chemistry B
Volume102
Issue number7
DOIs
Publication statusPublished - 12 Feb 1998
Externally publishedYes

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