Dynamic C-13 NMR studies of ligand exchange in linear (d(10)) silver(I) and gold(I) and square-planar (d(8)) rhodium(I) homoleptic metal carbonyl cations in superacidic media

The dynamic CO exchange of the monovalent metal carbonyl cations [Ag((CO)-C-13)](+), [Au((CO)-C-13)(2)](+)-Au((CO)-C-13) SO3F and [Rh((CO)-C-12)(4-x)((CO)-C-13)(x)](+) (x <= 1) in superacidic solutions was studied by variable-temperature C-13 NMR methods. The exchange rates are strongly dependent on the acidity of the solvent, the concentration of metal carbonyl cations and temperature. Whereas a suitable exchange rate of the Ag(I) system is only accessible in magic acid (HSO3F-SbF5), the more stable Au(I) and Rh(I) systems were studied in the less acidic fluorosulfuric acid. Selected solutions of Ag(I), Rh(I) and Au(I) yielded activation barriers Delta G* of 42.7, 43.5, and 56.2 kJ mol(-1) respectively. Copyright (c) 2005 John Wiley & Sons, Ltd.