η⁶-Coordination of a Ruthenium(II) Organometallic Fragment to the Arene Ring of N,C,N-Pincer Metal Complexes

Stable heterobimetallic complexes of the type [MX(NCN)Ru(C5R5)]+ (R = H or Me), where the phenylene ring of an NCN-pincer ligand coordinates first to a platinum or palladium center via a σ-bond, and second to a ruthenium organometallic fragment via a π-bond, are synthesized in a single step involving electrophilic attack of a cationic Ru species on the aryl metal complex. X-ray crystal structures and solution NMR agree on the simultaneous presence of orthogonal η6- and η1-coordination axes. 195Pt NMR and electrochemistry show that the η6-coordinated ruthenium fragment has a strong electron-withdrawing effect on the pincer metal, which leads to a diminished nucleophilicity of the platinum center toward electrophiles such as SO2.