Specific Activation of CH‐ and CC‐Bonds by Bare Transition‐Metal Ions

Abstract

AbstractChemists are continuously facing questions and problems as follows: Is it possible to direct the course of a reaction according to one's intentions? Is the activation of specific bonds that are either remote or adjacent to a functional group feasible? What factors dictate the different behaviour of transition‐metal ions in their reactions with organic substrates? Answers to these and other questions are provided by studying the gas‐phase chemistry of “naked” first‐row transition‐metal ions with aliphatic nitriles and some other simple organic substrates. By systematically modifying both the organic molecules and the metal ions, a quite detailed insight is achieved into the mechanisms that are operative, and knowledge is accumulated which permits to specify the conditions that are to be met in order to bring about specific processes. “Remote functionalization”, the generation of ion/dipole intermediates, and the formation of multi‐ligated metal‐ion alkene complexes turn out to be the most important mechanisms in the reactions of aliphatic nitriles with transition‐metal ions in the gas phase. In addition, results will be presented which point to degenerate isomerizations involving metallacycles as intermediates. We will also demonstrate that direct CC bond activation prior to CH bond activation can be achieved, a process for which no analogue exists in solution chemistry. The studies have been performed by using tandem mass spectrometry techniques in a sector‐field mass spectrometer as well as ion/molecule reactions in a Fourier transform ion cyclotron resonance (FTICR) instrument.