Do Platinum(II) and Palladium(II) Phosphinito Phosphinous Acids Generate the Same Type of Reactive Intermediate in Alkyne Coordination? A Gas-Phase Study with Phenylethyne and Propargyl Acetate
Résumé
The structure and behavior of the catalytic species involved in the PAPd- and PAPt-catalyzed formal [2 + 1] cycloaddition between an alkyne and norbornadiene have been studied by combined mass spectrometry experiments and density functional theory calculations. The first step of this reaction, the coordination of the catalyst with the alkyne, is also investigated under collision-activated reaction conditions. Two different structures are proposed for the key intermediates: an acetylide structure for Pd and a metallacarbene for Pt.