Synthesis, Crystal Structure, and Redox and Photophysical Properties of Novel Bisphosphinoaryl RuII-Terpyridine Complexes

Novel organometallic [Ru(PCP)(tpy)]Cl complexes, containing the terdentate coordinating monoanionic bisphosphinoaryl ligands [C6H3(CH2PR2)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{C6H2(CH2PPh2)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{C6H3(CH2NMe2)2-2,6}(tpy)](Cl) (3) containing the monoanionic bisaminoaryl ligand [C6H3(CH2NMe2)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.