Oxygen Insertion into Metal Carbon Bonds: Formation of Methylperoxo Pd(II) and Pt(II) Complexes via Photogenerated Dinuclear Intermediates

Platinum­(II)
and palladium­(II) complexes [M­(CH3)­(L)]­SbF6 with substituted terpyridine ligands L undergo
light-driven oxygen insertion reactions into metal
methyl bonds resulting in methylperoxo complexes [M­(OOCH3)­(L)]­SbF6. The oxygen insertion reactions
occur readily for complexes with methyl ligands that are activated
due to steric interaction with substituents (NH2, NHMe
or CH3) at the 6,6″-positions on the terpyridine
ligand. All complexes exhibit attractive intermolecular π···π
or M···M interactions in the solid state and in solution,
which lead to excited triplet dinuclear M–M complexes upon
irradiation. A mechanism is proposed whereby a dinuclear intermediate
is generated upon irradiation that has a weakened M–C bond
in the excited state, resulting in the observed oxygen insertion reactions.