Organometallic complexes for nonlinear optics: Part 31. Cubic hyperpolarizabilities of ferrocenyl-linked gold and ruthenium complexes

The complexes [Fe{η-C5H4(E)CHCH4-C6H4CCX}2] [X=SiMe3 (1), H (2), Au(PCy3) (3), Au(PPh3) (4), Au(PMe3) (5), RuCl(dppm)2 (7), RuCl(dppe)2 (8)] and [Fe{η-C5H4(E)CHCH4-C6H4CHCRuCl(dppm)2}2](PF6)2 (6) have been prepared and the identities of 1 and 7 confirmed by single-crystal X-ray structural studies. Complexes 1–8 exhibit reversible oxidation waves in their cyclic voltammograms attributed to the FeII/III couple of the ferrocenyl groups, 6–8 also showing reversible (7, 8) or non-reversible (6) processes attributed to Ru-centered oxidation. Cubic nonlinearities at 800 nm by the Z-scan method are low for 1–5; in contrast, complexes 6 and 7 exhibit large negative γreal and large γimag values. A factor of 4 difference in ∣γ∣ and two-photon absorption cross-section σ2 values for 6 and 7 suggest that they have potential as protically switchable NLO materials.