Spectroscopic Characterization and Catalytic Application of Copper(I), Silver(I) and Gold(I) Carbonyl Cations in Strong Acids

Abstract

Abstract Detailed IR, Raman, and NMR spectroscopic characterization has been carried out on the group 11 metal carbonyl cations, Cu(CO)n+ (n = 1, 2, 3, 4), Ag(CO)n+ (n = 1, 2, 3), and Au(CO)n+ (n = 1, 2), over a wide range of temperature and in a variety of strong acids. Based on these results their molecular structures were determined and their stabilities are compared and discussed. The active species have been determined to be Cu(CO)2+ (and Cu(CO)3+ as a minor species) instead of the previously assigned Cu(CO)3+, Ag(CO)+ instead of the previously assigned Ag(CO)2+, and Au(CO)2+, respectively, for the copper(I), silver(I) and gold(I) carbonyl cation-catalyzed carbonylation of olefins and alcohols in concentrated sulfuric acid. The reaction mechanism previously proposed for the metal carbonyl cation-catalyzed carbonylation has been modified to involve an olefin-metal-monocarbonyl (e.g., for Ag) or an olefin-metal-polycarbonyl (e.g., for Cu or Au) intermediate.