Ruthenium Vinyl Research Articles

Synthesis, Characterization, and Substituent Effects of Binuclear Ruthenium Vinyl Complexes [RuCl(CO)(PMe3)3]2(μ-CH═CH−Ar−CH═CH)

A series of binuclear ruthenium vinyl complexes [RuCl(CO)(PMe3)3]2(μ-CH═CH−Ar−CH═CH) (Ar = C6H4 (6a), C6H3CH3 (6b), C6H3OCH3 (6c), C6H3F (6d), C6H3Cl (6e), C6H3Br (6f), C6H3CN (6g), C6H3NO2 (6h), C6H2(CH3)2-2,5 (6i), C6H2(OCH3)2-2,5 (6j), C6H2(F)2-2,5 (6k), C6H2(CF3)2-2,5 (6l), and C6H3CF3 (6m)) have been prepared. The respective products have been characterized by elemental analyses, NMR spectrometry, and UV/vis spectrophotometry. The structures of 6h, 6i, and 6j have been established by X-ray crystallography. Electrochemical studies have revealed that intermetallic electron communication between the two Ru centers may be fine-tuned by modification of the bridging spacers, that is, by introducing one or two substituent groups on the 1,4-diethenylphenylene bridge. Electron-releasing substituents have been found to facilitate electron communication between the two metal centers.

Ruthenium Complexes with Vinyl, Styryl, and Vinylpyrenyl Ligands: A Case of Non-innocence in Organometallic Chemistry

We herein describe a systematic account of mononuclear ruthenium vinyl complexes L-{Ru}-CH=CH-R where the phosphine ligands at the (PR'3)2Ru(CO)Cl={Ru} moiety, the coordination number at the metal (L = 4-ethylisonicotinate or a vacant coordination site) and the substituent R (R = nbutyl, phenyl, 1-pyrenyl) have been varied. Structures of the enynyl complex Ru(CO)Cl(PPh3)2(eta1:eta2-nBuHC=CHCCnBu), which results from the coupling of the hexenyl ligand of complex 1a with another molecule of 1-hexyne, of the hexenyl complexes (nBuCH=CH)Ru(CO)Cl(PiPr3)2 (1c) and (nBuCH=CH)Ru(CO)Cl(PPh3)2(NC5H4COOEt-4) (1b), and of the pyrenyl complexes (1-Pyr-CH=CH)Ru(CO)Cl(PiPr3)2 (3c) and (1-Pyr-CH=CH)Ru(CO)Cl(PPh3)3 (3a-P) have been established by X-ray crystallography. All vinyl complexes undergo a one-electron oxidation at fairly low potentials and a second oxidation at more positive potentials. Anodic half-wave or peak potentials show a progressive shift to lower values as pi-conjugation within the vinyl ligand increases. Carbonyl band shifts of the metal-bonded CO ligand upon monooxidation are significantly smaller than is expected of a metal-centered oxidation process and are further diminished as the vinyl CH=CH entity is incorporated into a more extended pi-system. ESR spectra of the electrogenerated radical cations display negligible g-value anisotropies and small deviations of the average g-value from that of the free electron. The vinyl ligands thus strongly contribute to or even dominate the anodic oxidation processes. This renders them a class of truly "non-innocent" ligands in organometallic ruthenium chemistry. Experimental findings are fully supported by quantum chemical calculations: The contribution of the vinyl ligand to the HOMO increases from 46% (Ru-vinyl delocalized) to 84% (vinyl dominated) as R changes from nbutyl to 1-pyrenyl.

Hydrogen transfer type oxidation of alcohols by rhodium and ruthenium catalyst under microwave irradiation

Secondary alcohols were converted into the corresponding ketones by methyl acrylate and rhodium catalyst efficiently under microwave irradiation. Treatment of primary alcohols with the same condition resulted in the recovery of the starting materials. Primary alcohols were converted into aldehydes by hydrogen transfer reaction using methyl vinyl ketone and ruthenium catalyst under microwave irradiation.

Oxidatively Induced Carbonylation and Cyclization of Ruthenium(II) Vinyl−Olefin Complexes Prepared via Allyl/Alkyne Coupling

One-electron oxidation of otherwise unreactive ((1:4,5-η)-1,4-pentadien-1-yl)ruthenium carbonyl complexes in acetonitrile under carbon monoxide leads to the formation of 5-methylene-2-cyclopenten-1-ones via carbonylation, migratory cyclization, and β-hydride elimination. Oxidation in dichloromethane produces an acyclic 1,4-pentadiene, even under a carbon monoxide atmosphere.

Dimeric and polymeric ruthenium complexes with Ru—vinyl linkages

Abstract The carbonyl hydrido complex RuHCl(CO)(PPh 3 ) 3 reacted with diynes HC≡C-R-C≡CH (R = p -C 6 H 4 , p -C 6 H 4 -C 6 H 4 ) to give the five-coordinate vinyl ruthenium dimeric compounds [RuCl(CO)(PPh 3 ) 2 ] 2 (μ-CH=CH-R-CH=CH) in high yields. Additions of 2,6-di-methylphenyl isocyanide (CNC 8 H 9 ) or 4-phenylpyridine (Ph-Py) to the vinyl complexes produced the six-coordinate adducts [RuCl(CO)(C 8 H 9 NC)(PPh 3 ) 2 ] 2 (μ-CH=CH-R-CH=CH) and [RuCl(CO)(Ph-Py)(PPh 3 ) 2 ] 2 (μ-CH=CH-R-CH=CH) respectively. Reactions of [RuCl(CO)(PPh 3 ) 2 ] 2 (μ-CH=CH-R-CH=CH) with L (L = 2,3,5,6-tetramethylphenyl diisocyanide or 4,4′-bipyridine) produced [RuCl(CO)(PPh 3 ) 2 (μ-CH=CH-R-CH=CH)RuCl(CO)(PPh 3 ) 2 (μ-L)] x .