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Diruthenium Complexes (diruthenium + complex)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Multicomponent Supramolecular Devices: Synthesis, Optical, and Electronic Properties of Bridged Bis-dirhodium and -diruthenium Complexes,

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2006
Anne Petitjean
Abstract 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 (metal,metal 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 ,s) 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) [source]

Synthesis, Characterization and Reactivity of New (,-Aminocarbyne)diruthenium Complexes Containing Alkynylimino Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2004
Luigi Busetto
Abstract Addition of acetylides R,C,CLi [R, = Tol, Ph, Me3Si, nBu, C(Me)=CH2] to the diruthenium complexes [Ru2{,-CN(Me)(R)}(,-CO)(CO)(NCCMe3)(Cp)2]+ (R = Xy, 2a; Bz, 2b; Me, 2c) results in the formation of [Ru2{,-CN(Me)(R)}(,-CO)(CO){N(H)=C(CMe3)(C,CR,)}(Cp)2]+ (R = Xy, R, = Tol, 3a; R = Bz, R, = Tol, 3b; R = Me, R, = Tol, 3c; R = Xy, R, = Ph, 4a; R = Bz, R, = Ph, 4b; R = Me, R, = Ph, 4c; R = Bz R, = H, 5; R = Xy, R, = nBu, 6; R = Xy, R, = [C(Me)=CH2], 7), which contain an alkynylimino ligand, formed from addition of the acetylide to the Me3CCN ligand. Structural and spectroscopic studies show that all these complexes contain the two Cp ligands in a relative cis arrangement, whereas two isomers arise from the different orientation of the substituents on the bridging aminocarbyne ,-CN(Me)(R) when R , Me. Addition of secondary amines to 3,7 results in a stereo- and regioselective cis amination of the C,C triple bond to give the new complexes [Ru2{,-CN(Me)(R)}(,-CO)(CO){N(H)=C(CMe3)C(H)=C(NMe2)(Tol)}(Cp)2]+ (R = Xy, 8a; Bz, 8b; Me, 8c), [Ru2{,-CN(Me)(Xy)}(,-CO)(CO){N(H)=C(CMe3)C(H)=C(NC5H10)(Tol)}(Cp)2]+(9) and [Ru2{,-CN(Me)(Xy)}(,CO)(CO){N(H)=C(CMe3)C(H)=C(NMe2)C(Me)=CH2)}(Cp)2]+ (10) containing the hitherto unknown new imino-2-en-3-amine ligand. The solid-state structures of these products have been analyzed by X-ray analysis and, in solution, by NOE spectroscopic studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Ruthenium-Catalyzed Propargylic Substitution Reactions of Propargylic Alcohols with Oxygen-, Nitrogen-, and Phosphorus-Centered Nucleophiles

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2005
Yoshiaki Nishibayashi Dr.
Abstract The scope and limitations of the ruthenium-catalyzed propargylic substitution reaction of propargylic alcohols with heteroatom-centered nucleophiles are presented. Oxygen-, nitrogen-, and phosphorus-centered nucleophiles such as alcohols, amines, amides, and phosphine oxide are available for this catalytic reaction. Only the thiolate-bridged diruthenium complexes can work as catalysts for this reaction. Results of some stoichiometric and catalytic reactions indicate that the catalytic propargylic substitution reaction proceeds via an allenylidene complex formed in situ, whereby the attack of nucleophiles to the allenylidene C, atom is a key step. Investigation of the relative rate constants for the reaction of propargylic alcohols with several para -substituted anilines reveals that the attack of anilines on the allenylidene C, atom is not involved in the rate-determining step and rather the acidity of conjugated anilines of an alkynyl complex, which is formed after the attack of aniline on the C, atom, is considered to be the most important factor to determine the rate of this catalytic reaction. The key point to promote this catalytic reaction by using the thiolate-bridged diruthenium complexes is considered to be the ease of the ligand exchange step between a vinylidene ligand on the diruthenium complexes and another propargylic alcohol in the catalytic cycle. The reason why only the thiolate-bridged diruthenium complexes promote the ligand exchange step more easily with respect to other monoruthenium complexes in this catalytic reaction should be that one Ru moiety, which is not involved in the allenylidene formation, works as an electron pool or a mobile ligand to another Ru site. The catalytic procedure presented here provides a versatile, direct, and one-step method for propargylic substitution of propargylic alcohols in contrast to the so far well-known stoichiometric and stepwise Nicholas reaction. [source]