Synthesis, crystal structure, and redox and photophysical properties of novel bisphosphinoaryl Ru II-terpyridine complexes

Novel organometallic [Ru(PCP)(tpy)]Cl complexes, containing the terdentate coordinating monoanionic bisphosphinoaryl ligands [C 6H 3(CH 2PR 2) 2-2,6] - (PCP) (R = Ph (11); iPr (12)) and 2,2′:6′,2″-terpyridine, have been synthesized by two different synthetic pathways in good yields. The molecular structure in the solid state of [Ru{C 2H 2(CH 2PPh 2) 2-2,6}(tpy)](OTf) (14) has been determined by X-ray crystallography. The spectroscopic and electrochemical properties of the [Ru(PCP)(tpy)]Cl complexes were compared with those obtained for [Ru{C 6H 3(CH 2NMe 2) 2-2,6}(tpy)](Cl) (3) containing the monoanionic bisaminoaryl ligand [C 6H 3(CH 2NMe 2) 2-2,6]- (NCN). The obtained results revealed that substitution of the NCN-pincer ligand by PCP-pincer ligands offers a powerful tool to tune the redox and photophysical properties as well as the reactivity of the ruthenium(II) metal centers in the resulting photoactive monomeric species.