Ruthenium dimeric complexes, reaction with

An electrophilic palladation by a phenyl palladium intermediate at C(3) and a C(3) to C(2) migration of a palladium species, followed by reductive elimination, is indicated. 2-Phenylpyridine has been formed by the reaction of pyridine and iodobenzene at 150 °C in the presence of phosphido-bridged ruthenium dimer complexes.49 A catalytic cycle involving one of the complexes in the system was proposed. Optimum conditions for the efficient and regioselective palladium-catalysed C(2) arylation of ethyl 4-oxazolecarboxylate (47) with iodobenzene have been presented.50... 

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). 

We had established in previous catalytic reactions involving complex 24 that this precatalyst was activated by the removal of the cod (1,5-cyclooctadiene) from the ruthenium by its reaction with the alkyne substrate via a [2 + 2 + 2] cydization as illustrated in Equation 1.64 [57]. Thus, not only does this reaction constitute an activation of the Ru complex 24 by reacting off the cod, it also serves as a novel atom economic reaction in its own right. Both internal and terminal alkynes participate. The overall atom economy of this process is outstanding since cod itself is simply available by the nickel-catalyzed dimerization of butadiene. Thus, the tricyclic product is available by the simple addition to two molecules of butadiene and an alkyne with anything else only needed catalytically. 

Ruthenium hydride complexes, e.g., the dimer 34, have been used by Hofmann et al. for the preparation of ruthenium carbene complexes [19]. Reaction of 34 with two equivalents of propargyl chloride 35 gives carbene complex 36 with a chelating diphosphane ligand (Eq. 3). Complex 36 is a remarkable example because its phosphine ligands are, in contrast to the other ruthenium carbene complexes described so far, arranged in a fixed cis stereochemistry. Although 36 was found to be less active than conventional metathesis catalysts, it catalyzes the ROMP of norbornene or cyclopentene. 

Several complexes with cobalt in the unusually high oxidation state of (-(- 4) were reported (198,202,280) in 1974. All of the complexes reported were prepared by reaction of [Codlidtcls] with BF3 or Et20BF3 in the presence of air. The complexes were formulated (202, 280) as [Co(R2dtc)3]BF4 (R = Me, Et, Pr, or cyclohexyl), but Hendrickson and Martin (198) suggested that dimeric [Co2(R2dtc)5]BF4 (Rj = Me2, Et2 pyrrolidyl, MeBu", or Bzj), Co(III) complexes, form that are analogous with the ruthenium(III) complex discussed earlier. 

Scheme 3 shows the details of the synthetic strategy adopted for the preparation of heteroleptic cis- and trans-complexes. Reaction of dichloro(p-cymene)ruthenium(II) dimer in ethanol solution at reflux temperature with 4,4,-dicarboxy-2.2 -bipyridine (L) resulted the pure mononuclear complex [Ru(cymene)ClL]Cl. In this step, the coordination of substituted bipyridine ligand to the ruthenium center takes place with cleavage of the doubly chloride-bridged structure of the dimeric starting material. The presence of three pyridine proton environments in the NMR spectrum is consistent with the symmetry seen in the solid-state crystal structure (Figure 24). 

Loss of Coordinated Arene. We previously stated that the arene ligand in ruthenium(II)-arene complexes is relatively inert towards displacement under physiological conditions. While this is generally true, there are a few exceptions to this rule and this type of reactivity can be used to advantage. Weakly bound arenes, for instance, can be thermally displaced, a property convenient for the synthesis of ruthenium-arene complexes that are not readily available through more common synthetic routes. This way, the reaction of a precursor dimer, [RuCl2(etb)]2 (etb, ethylbenzoate) (68), with either 3-phenyl-1-propylamine or... 

Introduction of mesityl groups at the porphyrin ring can prevent the formation of the dimeric products and the reaction with dioxygen now leads to ruthenium(VI)-dioxo complexes of TMP (tetramesitylporphyrin) [35], The tram-Ru(VI)02-TM P species can catalyse the epoxidation of alkenes as well as whole range of other oxidation reactions. After transfer of one oxygen atom to an organic substrate Ru(IV)0-TMP is formed, which disproportionates to an equilibrium of Ru02 and llu ). 

A bis(cyclophane)ruthenium(II) complex has been prepared by using Bennett s procedure reaction of diene 265, obtained by Birch reduction of 4,5,7,8-tetramethyl[22](l,4)cyclophane 266, with ruthenium chloride gives the dimeric chloride complex 267 (Scheme 27, p. 223). Treatment of the solvated complex 268 with 266 in the presence of trifluoroacetic acid leads to 269 (163). The structures of complexes 267, 268, and 269 are based on ... 

The earliest report of a ruthenium corrole complex appeared in the literature in 2000 [64], and the most recent in 2003 [179]. The initial report described the synthesis of the face-to-face dimer [Ru(hedmc)]2 (Fig. 15), synthesized by reaction of P hedmc with [Ru(cod)Cl2]2 (where cod = 1,5-cyclooctadiene) in 2-methoxyethanol in the presence of trimethylamine. This complex displays an extremely blue-shifted Soret electronic absorption system, with minimal Q-band intensity. The Ru-Ru bond distance is 2.166(1) A the Ru atoms are displaced toward one another and out of the corrole plane by 0.514(4) A. Based on the MO description of Collman and Arnold... 

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