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Title: Trigonal-pyramidal tetra-sandwich complexes as 3D NLOphores
Authors: Steffens, Stefan ×
Prosenc, Marc H
Heck, Juergen
Asselberghs, Inge
Clays, Koen #
Issue Date: Apr-2008
Publisher: Wiley-VCH
Series Title: European Journal of Inorganic Chemistry issue:12 pages:1999-2006
Abstract: The Negishi cross-coupling reaction of 1,3,5-trihalobenzene with ferrocenyl- and ruthenocenyllithium, yields the corresponding 1,3,5-trimetallocenylated benzene derivatives in good yield, when 1,3,5-triiodobenzene is used. In a subsequent stacking reaction with the cationic (eta(5)-cyclopentadienyl)ruthenium(II) and (eta(5)-pentamethylcyclopentadienyl)ruthenium(II) half-sandwich complexes to the central benzene ring, the trigonal-pyramidal tetra-sandwich complexes (il'-cyclopentadienyl)(eta(6)-1,3,5-triferrocenylbenzene)ruthenium(II) hexafluorophosphate (4), (eta(5)-pentamethylcyclopentadienyl)(eta(6)-1,3,5-triferrocenylbenzene)rutheni- um(II) hexafluorophosphate (5) and (eta(5)-cyclopentadienyl)-(eta(6)-1, 3,5-triruthenocenylbenzene)ruthenium(II) hexafluorophosphate (6) are formed. X-ray structure analyses of the complexes 4 and 6 confirm the trigonal-pyramidal architecture composed of four sandwich units. Cyclic voltammetric studies of the ferrocenyl-containing complexes 4 and 5 reveal only one reversible redox couple with a peak separation of Delta E-p < 80 mV, demonstrating a negligible mutual electronic influence of the ferrocenes in all meta positions. The positive charge of the central sandwich cation shifts the oxidation potential anodically to +186(5) and +154(5) mV vs. ferrocene/ferrocenium for 4 and 5, respectively. Based on a charge/NMR shift correlation, the charge flow from the metallocenes to the central sandwich unit can be calculated. Concerning the second harmonic generation (SHG), 4 demonstrates a larger first hyperpolarizability beta than the all-ruthenium congener 6 due to the better electron-donating properties of the ferrocene substituents. The structural data, the redox behaviour and the experimentally obtained charge flow from the donor to the acceptor units are in good agreement with the results of corresponding I)FT calculations. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).
ISSN: 1434-1948
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Imaging and Photonics
× corresponding author
# (joint) last author

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