NMR Study of the Structure of Simple Molecules Adsorbed on Metal Surfaces:C2H2on Pt

Abstract

The authors have used NMR to determine the structure of ${\mathrm{C}}_2$ ${\mathrm{H}}_2$ adsorbed at room temperature on small platinum particles by probing the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$-${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$-${}_{}{}^1{}_{}{}^{}\mathrm{H}$, and ${}_{}{}^1{}_{}{}^{}\mathrm{H}$-${}_{}{}^1{}_{}{}^{}\mathrm{H}$ dipolar interactions among the nuclei in the adsorbed molecules. They find a model of (77 ± 7)% CC${\mathrm{H}}_2$ and (23 ± 7)% HCCH. The C-C bond length of the CC${\mathrm{H}}_2$ is 1.44 ± 0.02 Å, midway between a single and double bond, suggesting that both C atoms bond to the surface.