Formation of η3-Allyl and Its Cryogenic Coupling Reaction with Allyl Bromide on Cu(100)

Abstract

Over the past three decades, a variety of transition metal-catalyzed coupling reactions between organometallic nucleophiles and organic halide electrophiles have become important processes for the formation of carbon-carbon bond in both heterogeneous catalysis and organometallic chemistry. The authors report for the first time the facile formation of 1,5-hexadiene at cryogenic temperatures (110 K) while dosing allyl bromide on Cu(100) covered with {eta}{sup 3}-allyl and bromide atoms. This cryogenic coupling reaction in ultrahigh vacuum (UHV) conditions is akin to metal-catalyzed coupling reactions in solutions and on heterogeneous catalysts. Furthermore, it contrasts with typical carbon-carbon coupling reactions of adsorbed alkyl and vinyl groups on Cu and other transition metals under ultrahigh vacuum (UHV) conditions. These workers also report the first high-resolution reflection absorption infrared spectrum (RAIRS) of the chemisorbed {eta}{sup 3}-allyl group. Such spectra have the potential to address ambiguities in the mechanistic interpretations of the formation of C{sub 3} species, for example, propylene.