Cyclopentadienyl ruthenium complexe

Compound 127 is a useful starting material in preparing a variety of arene cyclopentadienyl ruthenium complexes of type 125 by... 

Cyclopentadienyl dicarbonyl ruthenium dimer 132 reacts with silver tetrafluoroborate and diphenylacetylene to afford the cyclobutadiene ruthenium complex 133 (Scheme 12). Irradiation of 133 in dichloro-methane in the presence of several alkynes leads to the arene cyclopentadienyl ruthenium complexes 125 in high yield. This reaction appears to be a general route to sterically crowded ruthenium arene cations (55). 

However, in the presence of (cyclopentadienyl)ruthenium complexes bearing an electron-rich ligand such as tris(p-methoxyphenyl)phosphine in the presence of a large excess of the same ligand, the selective formation of lactones was achieved. The recovery of the organic ligand as a lactone was made possible by oxidation with N-hydroxysuccinimide, a mild oxidant which does not destroy the catalyst (Scheme 8.10) [21],... 

Creation of a vacant site by CO dissociation is favored at low CO pressures, whereas the CO insertion step seems not to be very sensitive to pressure. Above 150°C the cyclopentadienyl ruthenium complex was destroyed, and many complexes were formed, with [Ru3(CO),2] as the major component. This mixture of compounds is of poor activity, and [Ru3(CO),2] tested under the same conditions presents the same low level of catalytic activity. 

Cyclopentadienyl Ruthenium Complexes Valuable Assistents in the Construction of Carbon-Carbon Bonds... 

Cyclopentadienyl Ruthenium Complexes Valuable Assistants in the Construction. ... 

Scheme 1.30 p-H elimination versus CO insertion in cyclopentadienyl ruthenium complexes. 

Aqueous phase carbon dioxide and bicarbonate hydrogenation catalysed by cyclopentadienyl ruthenium complexes. Appl Organomet Chem 21 947-951... 

Fish and co-workers have studied N-to-77 rearrangements of a number of cyclopentadienyl rhodium and ruthenium complexes of pyridines and quinolines. This behavior was first observed in the complex [Ru(C5H5)(CH3CN)2(2-Mepy)]+ where the cr-bound N-isomer (15) gave an equilibrium mixture of the N- and w-bound (16) complexes on heating in 1,2-dichloroethane (ratio 15 16 = 6 1). No free ligand was detected in... 

Half-sandwich ruthenium complexes bearing a cyclopentadienyl (Cp), a pentamethylcyclopentadienyl (Cp ),or an indenyl ligand. 

Recent efforts to explore the synthesis and reactivity of organotransition metal complexes with the cyclopentadienyl bisphosphine ruthenium auxiliary have emphasized the potential of this system for the development of new organic synthetic methods, but they have also uncovered a number of stumbling blocks which must be overcome to achieve real success in this area. Future developments in the chemistry of these ruthenium complexes will be based on the successful application of the reactivity trends uncovered in the past work. The rapid expansion of studies in this field since the mid-1980s has made it increasingly difficult for the synthetic chemist to... 

Photolysis of complex 125 (arene = benzene) in acetonitrile gives a quantitative yield of cyclopentadienyl tris(acetonitrile) ruthenium complex... 

Benzene cyclopentadienyl ruthenium(II) complex 125 undergoes nucleophilic addition at the arene ligand via the addition of sodium borohy-dride or phenyllithium. Reaction with phenyllithium gives the exo-phenyl cyclohexadienyl derivative 249 in 89% yield (154) [Eq. (32)]. 

Osmium forms a wide variety of alkyl and aryl complexes including homoleptic alkyl and aryl complexes and many complexes with ancillary carbonyl (see Carbonyl Complexes of the Transition Metals), cyclopentadienyl (see Cyclopenta-dienyl), arene (see Arene Complexes), and alkene ligands (see Alkene Complexes). It forms stronger bonds to carbon and other ligands than do the lighter elements of the triad. Because of this, most reactions of alkyl and aryl osmium complexes are slower than the reactions of the corresponding ruthenium complexes. However, because osmium is more stable in higher oxidation states, the oxidative addition (see Oxidative Addition) of C-H bonds is favored for osmium complexes. The rate of oxidative addition reactions decreases in the order Os > Ru Fe. 

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