The Fate of Sulfur-Bound Hydrogen on Formation of Self-Assembled Thiol Monolayers on Gold:  1H NMR Spectroscopic Evidence from Solutions of Gold Clusters

• Published in: Journal of the American Chemical Society Vol. 124; no. 7; pp. 1132 - 1133
• Main Authors: Hasan, Masihul, Bethell, Donald, Brust, Mathias
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 20.02.2002
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solid-liquid interface; Surface physical chemistry; Monolayer; Gold; Liquid solid interface; Liquid solid adsorption; Organic adsorbate; Chemical stability; Alkanethiol; Molecular interaction; Transition metal; NMR spectrometry; Experimental study; Metal cluster; Metallic adsorbent; Adsorption structure
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0120577

It is demonstrated that thiols can adsorb to gold without losing hydrogen. Dodecyl sulfide-capped gold clusters have been prepared and subjected to ligand exchange reactions in perdeuterated benzene by addition of dodecanethiol and subsequently dodecyl disulfide. It is shown by 1H NMR spectroscopy that dodecanethiol molecules are readily taken up as ligands producing characteristic broad signals corresponding to the α-methylene and S−H protons, with chemical shifts close to those found for thiol in solution; these signals are absent in spectra of thiolate-capped clusters. Addition of excess disulfide to such clusters capped with both dialkyl sulfides and thiols leads to the appearance of sharp signals for free dialkyl sulfide and intact thiol. Amounts of thiols up to 50% of the ligand shell are, however, taken up by the clusters under rapid and irreversible loss of hydrogen.