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

The compounds (E)-4-XC=CC6H4CH=CHPh [X = SiMe3 (1), H (2)],1,3,5- (E)-4-XC6H4CH CH}(3)C6H3 [X = 1 (3), C= CSiMe3 (4) C = CH (5)], [Au{(E)-4-C=CC6H4CH-CHPh}(L)] [L = PPh3 (6), PMe3 (7)], [Au(4-C=CC6H4C=CPh)(L)] [L = PPh3 (8), PMe3 (9)], 1,3,5-[(Ph3P)Au (E)-4-C=CC6H4CH=CH}](3)C6H3 (10), trans-[Ru (E)-4-C-CHC6H4CH=CHPh}Cl(dppm)(2)]PF6 (11), trans[Ru{(E)-4-C=CC6H4CH=CHPh}Cl(L-2)(2)] [L-2=dppm (12), dppe (13)], [1,3,5-(trans-[(dppm)(2)C]Ru{(E)-4-C-CHC6H4CH= CH}])(3)C6H3](PF6)(3) (14), 1,3,5-(trans-[(L-2)(2)ClRu{(E)-4-C-CC6H4CH-CH}])(3)C6H3 [L-2 = dppm (15), dppe (16)] and 1,3,5-(trans[(dppe)(2)(PhC=C)Ru (E)-4-C=CC6H4CH=CH}])(3)C6H3 (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 \gamma\(800) and two-photon absorption (TPA) cross-sections sigma(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 \gamma\(800) and sigma(2) values for organometallics thus far. Cubic nonlinearities lm(chi((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. (C) 2002 Elsevier Science B.V. All rights reserved.