Nitrene-functionalized ruthenium nanoparticles

Abstract

Ruthenium nanoparticles protected by ruthenium–nitrene π bonds were prepared by refluxing “bare” ruthenium colloids (2.12 ± 0.72 nm in diameter) and 4-dodecylbenezenesulfonyl azide in sec-butylbenzene. Thermogravimetric analysis (TGA) of the resulting nanoparticles showed that on average there were about 84.1 ligands on the nanoparticle surface. XPS studies showed a 1 : 1 atomic ratio between nitrogen and sulfur, consistent with the formation of nitrene fragments by the thermal decomposition of the azide precursors. In addition, the binding energies of Ru3d and N1s electrons suggested a covalent nature of the RuN interfacial linkage which appeared in FTIR measurements with a vibrational band at 1246 cm⁻¹. Because of such conjugated bonding interactions, extensive intraparticle charge delocalization occurred, and the nanoparticle-bound nitrene moieties behaved analogously to azo derivatives, as manifested in UV-vis and fluorescence measurements. Further testimony of the formation of RuN interfacial linkages was highlighted in the unique reactivity of the nanoparticles with alkenes by imido transfer, which was evidenced in spectroscopic and electrochemical studies.