Infrared spectra of CH3–MH, CH3–M, and CH3–MH− prepared viamethaneactivation by laser-ablated Au, Ag, and Cu atoms

Abstract

Methane activation by laser-ablated, excited Group 11 metal atoms has been carried out, leading to generation of CH₃–MH, CH₃–M, and CH₃–MH⁻, which are identified in the product infrared spectra on the basis of isotopic shifts and correlation with DFT calculated frequencies. The products reveal that C–H insertion by excited Au, Ag, and Cu readily occurs, and subsequent hydride-detachment or electron addition also follows. Each type of product has similar photochemical properties regardless of the metal. DFT computed energies reveal facile hydride dissociation and high electron affinities for the insertion complexes. The methyl metal species have the shortest C–M bonds, consistent with their highest calculated effective bond order, and the CH₃–MH complexes have higher electron affinities than the metal atoms.