Ruthenium catalysts binuclear

Binuclear Indenylidene Ruthenium Catalysts Arising from Ruthenium(arene) Complexes... 

The first attempt seems to have been promoted by binuclear ruthenium alkene metathesis catalyst for the ROMP of cyclooctene followed by hydrogenation (50 °C, 30 psi H2) in the presence of 10 equiv. of triethylamine [72] (Scheme 31). It was motivated by the observed capability of [RuCl2(arene)]2... 

Water oxidation is a thermodynamically unfavorable process which involves the transfer of four electrons. Several catalysts have been developed and simultaneously several mechanisms for these types of chemical transformations have been proposed [13]. Binuclear ruthenium complexes have drawn considerable attention in the context of water oxidation. The anthracene-bridged binuclear Ru bis-hydroxide bis-quinone... 

Unlike the reaction catalysed by [RuCl2(PPh3) (5)-biphemp ], a dimeric complex has been reported to play a direct role in the enantioselective conversion of acetylacetone to (i )-(/2)-2,4-pentanediol with the catalyst precursor [(BDPzP)(DMSO)Ru(p-C1)3RuC1(BDPBzP)] (BDPBzP = (R)-(R)-3-benzyl-2,4-bis(diphenylphosphino)pentane) (MeOH, 50 bar Hj, 50 °C) [68]. The binuclear complex [(BDPzP)C1(ti2-H2)Ru(h-H)2Ru(ti2-H2)(BDPBzP)] was actually detected by high-pressure NMR spectroscopy as the only ruthenium compound in the course of the catalytic reaction yielding (/ )-(/ )-2,4-pentanediol (Scheme 15). 

Binuclear complexes with bridging trimethyltriazoldiylidene ligands were also used in TH and p-alkylation reactions. Thus, complexes 76 and 77 were applied for TH of ketones and imines in i-PrOH/KOH (Figure 13.11). The reductions of ketones and A -benzylidene anilines were complete within 1 h. Related 78 and 79 ruthenium complexes were investigated as catalysts in the p-alkylation of secondary alcohols with primary alcohols. Such catalytic systems were very selective and more active than the previously reported catalysts. ... 

Using the binuclear ruthenium(II) catalyst [RuBr2(CO)2(PPh3)]2 Wai Yip Fan succeeded to achieve the alkenylation of pyrroles with terminal alkynes under mild conditions at 50°C. This catalyst leads to the reverse regioselectivity for hydroheteroarylation of alkynes and the dialkenylation of pyrrole can be controlled. The mechanism likely involves an electrophilic activation of the alkyne by the Ru (II) species favouring the nucleophilic Markovnikov addition of pyrrole to the alkyne internal carbon [(Eq. 78)] [162]. 

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