Multicomponent supramolecular devices: Synthesis, optical, and electronic properties of bridged bis-dirhodium and -diruthenium complexes.
Fiche publication
Date publication
octobre 2006
Auteurs
Membres identifiés du Cancéropôle Est :
Pr LEHN Jean-Marie
Tous les auteurs :
Petitjean A, Puntoriero F, Campagna S, Juris A, Lehn JM
Lien Pubmed
Résumé
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 M2LM2, 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 (metalmetal to ligand charge transfer, M2LCT). 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 M2LCT excited state of one of the bis-dirhodium. complexes is relatively long-lived (about 6 mu s) in degassed acetonitrile at room temperature. The results presented here are promising for the development of linear polydimetallic complexes built on longer naphthyridine-based strands, with significant long-range electronic coupling and molecular-wire-like behavior.
Référence
Eur J Inorg Chem. 2006 Oct 2;19:3878-92.