Gas-phase reactivity of Cp* group IX metal complexes bearing aromatic N,N′-chelating ligands

A set of cationic group IX metal complexes of the type [(eta(5)-Cp*) M(Cl)(N,N ')](+) bearing N,N '-coordinating ligands structurally related to 2,2 '-bipyridine were synthesized and characterized by means of elemental analysis, spectroscopy and single crystal X-ray diffraction. These complexes can undergo two different modes of CH activation in the gas phase, which were examined by CID ESI-MS spectrometry and by DFT calculations. On one hand, a roll-over cyclometallation can occur at one of the aromatic rings of the N,N '-coordinated ligands. On the other hand, a deprotonation of one of the Cp* methyl groups can take place, leading to complexes in the oxidation state +I with a tetramethylfulvene ligand coordinated. In both cases, the chlorido ligand acts as an internal base in the ESI-MS CID experiment.