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Multicomponent Supramolecular Devices: Synthesis, Optical, and Electronic Properties of Bridged Bis‐dirhodium and ‐diruthenium Complexes
Author(s) -
Petitjean Anne,
Puntoriero Fausto,
Campagna Sebastiano,
Juris Alberto,
Lehn JeanMarie
Publication year - 2006
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.200600466
Subject(s) - ruthenium , chemistry , rhodium , bridging ligand , metal , photochemistry , supramolecular chemistry , absorption spectroscopy , excited state , ligand (biochemistry) , homo/lumo , valence (chemistry) , molecular orbital , acceptor , acetonitrile , crystallography , electronic structure , molecule , computational chemistry , crystal structure , catalysis , organic chemistry , biochemistry , physics , receptor , quantum mechanics , nuclear physics , condensed matter physics
Four ruthenium‐ and rhodium‐based metal–metal‐bonded multicomponent systems have been synthesized, and their absorption, redox, spectroelectrochemical and structural properties have been studied. The absorption spectra of the four bis‐dimetallic compounds M 2 LM 2 , where L is a bridging ligand and M is rhodium or ruthenium, exhibit very strong bands in the UV, visible and, for the diruthenium species, near‐IR region. The low‐energy absorption bands are assigned to charge‐transfer transitions involving a metal–metal bonding orbital as the donor and an orbital centered on the bis‐tetradentate aromatic ligands as the acceptor (metal–metal to ligand charge transfer, M 2 LCT). Each compound exhibits reversible bridging‐ligand‐centered reductions at mild potentials and several reversible oxidation processes. The oxidation signals of the two equivalent dimetallic centers of each bis‐dimetallic compound are split, with the splitting — a measure of the electronic coupling — depending on both the metal and bridging ligand. The mixed‐valence species of the dirhodium species was investigated, and the electronic coupling matrix element calculated from the experimental intervalence band parameters for one of them (86 cm –1 ) indicates a significant inter‐component electronic interaction which compares well with good electron conducting anionic bridges such as cyanides. Although none of these compounds is luminescent, the M 2 LCT excited state of one of the bis‐dirhodium complexes is relatively long‐lived (about 6 μs) in degassed acetonitrile at room temperature. The results presented here are promising for the development of linear poly‐dimetallic complexes built on longer naphthyridine‐based strands, with significant long‐range electronic coupling and molecular‐wire‐like behavior. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)