Fluxional Behavior of Platinum(0) Complexes: Intra vs Intermolecular Reaction Pathways

The fluxional behavior of two analogous platinum complexes has been studied in solution by NMR spectroscopy to elucidate the reaction mechanism and to determine the activation parameters. This includes variable temperature NMR spectroscopy, 2D 1H−1H exchange spectroscopy, and spin saturation transfer measurements. A platinum moiety, Pt(PEt3)2, translocates between two carbon−carbon double bonds of two vinylpyridine moieties bridged by an arene (i.e., phenyl, anthracene) at elevated temperatures. Magnetization transfer NMR experiments in the presence of free ligands unambiguously revealed an intramolecular pathway for the “phenyl” system. An intermolecular pathway is proposed for the “anthracene” complex.