Stephanie K. Hurst

Organometallic Complexes for Nonlinear Optics Part 25. Quadratic and Cubic Hyperpolarizabilities of some Dipolar and Quadrupolar Gold and Ruthenium Complexes

Abstract The complexes [Au(4-CCC 6 H 4 NO 2 )(L)] [L=PCy 3 ( 1 ), PMe 3 ( 2 )], [(L)Au(μ-4-CCRCC)Au(L)] [R=C 6 H 4 , L=PCy 3 ( 4 ), PPh 3 ( 5 ); R=C 6 H 4 -4-C 6 H 4 , L=PCy 3 ( 7 ), PPh 3 ( 8 )], trans,trans -[RuCl(dppm) 2 (μ-4,4′-CCC 6 H 4 C 6 H 4 CC)RuCl(dppm) 2 ] ( 11 ), trans -[Ru(X)(Y)(dppe) 2 ] [X=Cl, Y=4-CCC 6 H 4 I ( 12 ), 4-CCC 6 H 4 CCSiMe 3 ( 13 ); X=CCPh, 4-CCC 6 H 4 CCH ( 14 )] and { trans -[Ru(CCPh)(dppe) 2 ]} 2 (μ-4,4′-CCC 6 H 4 CCCCC 6 H 4 CC) ( 15 ) have been prepared and their electrochemical (Ru complexes) and nonlinear optical properties assessed. Electronic communication between the metal centers in 10 , 11 and 15 diminishes as the π-delocalizable bridge is lengthened. Quadratic nonlinear optical (NLO) merit increases on replacing triarylphosphine by trialkylphosphine, the relative β values Au(4-CCC 6 H 4 NO 2 )(PPh 3 ) 1 3 being observed. Cubic NLO values are small for the gold complexes and much larger for the ruthenium examples. Complex 15 has the largest σ 2 /MWt (two-photon absorption cross-section/molecular weight) value observed thus far for an organometallic complex.

Organometallic complexes for nonlinear optics. Part 27. Syntheses and optical properties of some iron, ruthenium and osmium alkynyl complexes

The syntheses of the alkynyl complexes M(4-CCC6H4NO2)(dppe)(η-C5H5) [M=Fe (1), Ru (2), Os (3)], Os(4-CCC6H4NO2)(PPh3)2(η-C5H5) (4) and Ru(4-CCC6H4NO2)(CO)2(η-C5H5) (5) are reported. Structural studies reveal a decrease in RuC(1) distance on proceeding from 5 to 2, consistent with greater back-donation of electron density to the alkynyl ligand from the more electron-rich metal center in 2. Electrochemical data show that the MII/III couple for the dicarbonyl complex 5 is at a significantly more positive potential than that of the related diphosphine complex 2, consistent with ligand variation modifying the electron richness and hence donor strength of the metal center. Time-dependent density functional calculations on model complexes M(4-CCC6H4NO2)(PH3)2(η-C5H5) (M=Fe, Ru, Os) have been employed to assign the intense low-energy optical transition in these complexes as MLCT in character, the higher energy band being phenyl–phenyl* in nature. Molecular quadratic optical nonlinearities have been measured using the hyper-Rayleigh scattering procedure at 1064 nm. β values vary as Fe≤Ru≤Os for metal variation and CO<phosphines for co-ligand variation, the latter consistent with the variation in donor strength of the metal center inferred from electrochemical and crystallographic data. The observed trend in β on metal variation follows the trend in backbonding energies calculated by DFT.

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

Abstract 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.

Organometallic complexes for nonlinear optics. Part 29. Quadratic and cubic hyperpolarizabilities of stilbenylethynyl/gold and -ruthenium complexes

Abstract The compounds ( E )-4-XCCC 6 H 4 CHCHPh [X=SiMe 3 ( 1 ), H ( 2 )], 1,3,5-{( E )-4-XC 6 H 4 CHCH} 3 C 6 H 3 [X=I ( 3 ), CCSiMe 3 ( 4 ), CCH ( 5 )], [Au{( E )-4-CCC 6 H 4 CHCHPh}(L)] [L=PPh 3 ( 6 ), PMe 3 ( 7 )], [Au(4-CCC 6 H 4 CCPh)(L)] [L=PPh 3 ( 8 ), PMe 3 ( 9 )], 1,3,5-[(Ph 3 P)Au{( E )-4-CCC 6 H 4 CHCH}] 3 C 6 H 3 ( 10 ), trans -[Ru{( E )-4-CCHC 6 H 4 CHCHPh}Cl(dppm) 2 ]PF 6 ( 11 ), trans -[Ru{( E )-4-CCC 6 H 4 CHCHPh}Cl(L 2 ) 2 ] [L 2 =dppm ( 12 ), dppe ( 13 )], [1,3,5-( trans -[(dppm) 2 ClRu{( E )-4-CCHC 6 H 4 CHCH}]) 3 C 6 H 3 ](PF 6 ) 3 ( 14 ), 1,3,5-( trans -[(L 2 ) 2 ClRu{( E )-4-CCC 6 H 4 CHCH}]) 3 C 6 H 3 [L 2 =dppm ( 15 ), dppe ( 16 )] and 1,3,5-( trans -[(dppe) 2 (PhCC)Ru{( E )-4-CCC 6 H 4 CHCH}]) 3 C 6 H 3 ( 17 ) have been prepared (and the identity of 6 confirmed by a single-crystal X-ray diffraction study), and their electrochemical (Ru complexes) and nonlinear optical (NLO) properties assessed. The ruthenium complexes display reversible ( 12 , 13 , 15 – 17 ) or nonreversible ( 11 , 14 ) processes attributable to Ru-centered oxidation, at potentials similar to those of previously-investigated monoruthenium alkynyl or vinylidene complexes. No evidence for intermetallic electronic communication in 14 – 17 is observed. Quadratic nonlinearities at 1064 and 800 nm for the octopolar stilbenyl–ruthenium complexes 14 , 15 are large for compounds without strongly accepting substituents. Cubic molecular hyperpolarizabilities at 800 nm for the organic compounds and gold complexes are low. Cubic nonlinearities ∣ γ ∣ 800 and two-photon absorption (TPA) cross-sections σ 2 for the ruthenium complexes increase on proceeding from linear analogues 12 , 13 to octopolar complexes 15 , 16 ; the latter and 17 possess some of the largest ∣ γ ∣ 800 and σ 2 values for organometallics thus far. Cubic nonlinearities Im( χ (3) )/ N for 13 , 16 , and 17 from the first application of electroabsorption (EA) spectroscopy to organometallics are also large, scaling with the number of metal atoms.

Organometallic complexes for nonlinear optics ☆: Part 23. Quadratic and cubic hyperpolarizabilities of acetylide and vinylidene complexes derived from protected and free formylphenylacetylenes

The acetylenes 4-HCCC 6 H 4 R [R=CH{OC(O)Me} 2 ( 1 ), ( 2 )], ruthenium complexes [Ru(4-CCC 6 H 4 R)(PPh 3 ) 2 (η-C 5 H 5 )] [R=CH{OC(O)Me} 2 ( 3 ), CHO ( 4 )], [Ru( n -CCHC 6 H 4 R)Cl(dppm) 2 ]PF 6 [ n =4, R= ( 7 ); R=CHO, n =3 ( 11 ), 2 ( 15 )], and [Ru( n -CCC 6 H 4 R)Cl(dppm) 2 ] [ n =4, R= ( 8 ); n =3, R=CHO ( 12 )], and gold complexes [Au( n -CCC 6 H 4 R)(L)] [ n =4, R=CHO, L=PPh 3 ( 5 ), PMe 3 ( 6 ); n =4, R= , L=PPh 3 ( 9 ), PMe 3 ( 10 ); n =3, R=CHO, L=PPh 3 ( 13 ), PMe 3 ( 14 )] have been prepared, and 9 characterized by a single crystal X-ray diffraction study. Electrochemical data for the ruthenium complexes reveal reversible or quasi-reversible (alkynyl complexes) or irreversible (vinylidene complexes) processes assigned to the Ru II/III couple; the effect on E 1/2 values of the various structural modifications across 3 , 4 , 7 , 8 , 11 , 12 and 15 are discussed. The molecular quadratic and cubic optical nonlinearities of 1 – 15 have been determined by the hyper-Rayleigh scattering technique at 1064 nm and the Z -scan technique at 800 nm, respectively; β values increase on increasing the acceptor strength, proceeding from 3-acceptor-substituted to 4-acceptor-substituted arylalkynyl ligand, and an increasing phosphine donor strength, whereas γ values increase on increasing the number of phosphine aryl groups (i.e. increasing delocalization) proceeding from PMe 3 to PPh 3 -containing complex.

Organometallic Complexes for Non-Linear Optics. XXVI. Quadratic Hyperpolarizabilities of Some 4-Methoxytetrafluorophenylalkynyl Gold and Ruthenium Complexes

The complexes [Au(4-CA≡CC6F4OMe)(L)] [L = PMe3 (1), PPh3 (2)],trans-[Ru(4-C=CHC6F4OMe)Cl(dppm)2]PF6(3) and trans-[Ru(4-CA≡CC6F4OMe)Cl(dppm)2](4) have been prepared and the identity of (2) was confirmed by a structural study. Electrochemical data for (3) and (4) suggest that the 4-C6F4OMe group lies midway between Ph and 4-C6H4NO2in electron-withdrawing strength. Quadratic non-linearities at 1064 nm, determined by the hyper-Rayleigh scattering technique, increase for co-ligand variation, in the order PPh3 < PMe3, in proceeding from (2) to (1), whereas data for the vinylidene/alkynyl complexes (3) and (4) are experimentally indistinguishable. The quadratic non-linear optical data for (1) and (2) are comparable to those of their 4-nitrophenylalkynyl analogues, however, (1) and (2) are more optically transparent.