Synthesis and non-linear optical properties of (η5-pentaphenylcyclopentadienyl)dicarbonylruthenium(II) σ-alkenyl complexes

The complexes [Ru{(Z)-HCdouble bond; length as m-dashCHPh}(CO)2(η5-C5Ph5)] (1) and [Ru{(Z)-HCdouble bond; length as m-dashCHC6H4NO2}(CO)2(η5-C5Ph5)] (2) have been synthesized and their identity confirmed by single-crystal X-ray diffraction studies. Reaction of 2 with PMe2Ph and Me3NO in tetrahydrofuran afforded [Ru{(Z)-HCdouble bond; length as m-dashCHC6H4NO2}(CO)(PMe2Ph)(η5-C5Ph5)] (3). Cyclic voltammetry confirms the expected increase in ease of oxidation on proceeding from 2 to 1 and from 2 to 3. Hyper-Rayleigh scattering studies at 1064 nm reveal a dramatic increase in quadratic non-linearity on co-ligand replacement of CO by PMe2Ph, in proceeding from 2 to 3. Z-scan studies at 800 nm are consistent with significant contribution from two-photon states, and with an increase in γreal on co-ligand replacement of CO by PMe2Ph in proceeding from 2 to 3.