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Trigonal‐Pyramidal Tetra‐Sandwich Complexes as 3D NLOphores
Author(s) -
Steffens Stefan,
Prosenc Marc H.,
Heck Jürgen,
Asselberghs Inge,
Clays Koen
Publication year - 2008
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200701267
Subject(s) - hexafluorophosphate , chemistry , ruthenium , cyclopentadienyl complex , ferrocene , osmium , photochemistry , crystallography , inorganic chemistry , electrochemistry , organic chemistry , catalysis , ionic liquid , electrode
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 (η 5 ‐cyclopentadienyl)ruthenium(II) and (η 5 ‐pentamethylcyclopentadienyl)ruthenium(II) half‐sandwich complexes to the centralbenzene ring, the trigonal‐pyramidal tetra‐sandwich complexes (η 5 ‐cyclopentadienyl)(η 6 ‐1,3,5‐triferrocenylbenzene)ruthenium(II) hexafluorophosphate ( 4 ), (η 5 ‐pentamethylcyclopentadienyl)(η 6 ‐1,3,5‐triferrocenylbenzene)ruthenium(II) hexafluorophosphate ( 5 ) and (η 5 ‐cyclopentadienyl)(η 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 Δ 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 β 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 DFT calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)