Cyclopentadienyl ruthenium complexes

There is a pronounced tendency for ruthenium cyclopentadienyl complexes with attached phosphorus ligands to undergo a wide variety of intramolecular metallation reactions. Heating (T75-C5H5)(PPh3)2RuMe in decalin for 24 hours leads to the orthometallated complex 135 in reasonable yield [Eq. (Ill)] (6,103). The mechanism presumably involves initial loss of... 

Among the products of interaction of the ruthenium cyclopentadienyl complexes with alkynes, ruthenacycopenta-dienes and ruthenacyclopentatrienes occur quite often <1991JCD1589, 1997M1189, 1998CRV2599, 1998CRV2797,... 

Schdllkopfs chiral glycine enolate equivalents, as in the elegant synthesis of the central diarylether unit of ristocetin [169]. It is remarkable that these limitations were partly lifted by using, instead of the manganese tricarbonyl complex the corresponding iron or ruthenium cyclopentadienyl complexes [170] (Scheme 62). 

In 2005, ruthenium cyclopentadienyl complexes were found to catalyze the formation ofthe complementary 1,5-disubstituted triazole from azides and terminal... 

The vinylidene/acetyhdo interconversions carried out in this experiment are similar to those seen for other metal complexes" and are relevant to the known ability of (q -C5H5)RuCl(PPh3)2 to catalyze the dimerization of phenylacetylene to a mixture of Z- and -l,4-diphenyl-l-buten-3-yne. The chemistry of ruthenium cyclopentadienyl complexes has been reviewed. ... 

From the mechanistic point of view, the observed competitive reactions can be explained by considering two different pathways (Scheme 114). The intermediacy of ruthenacyclopentadiene 453 or biscarbenoid 452, formed from the reaction of a diyne and a ruthenium(ll) complex, is postulated in the proposed mechanism. Cyclopropanation of the alkene starts with the formation of ruthenacyclobutane 456, which leads to the generation of the vinylcarbene 457. Then, the second cyclopropanation occurs to afford the biscyclopropyl product 458. Insertion of the alkene 459 into the ruthenacyclopentadiene 453 affords the ruthenacycloheptadiene 454. The subsequent reductive elimination gives the cyclotrimerization product 455. The selectivity toward the bis-cyclopropyl product 458 is improved with an increasing order of haptotropic flexibility of the cyclopentadienyl-type ligand. 

HjNiOcjOsjCuHs, Osmium, nonacarbonyl-( tl -cyclopentadienyl )tri- x-hydridonickeltri-, 26 362 H,NiO,Ru,C14H5, Ruthenium, nonacar-bonyl-f-rf-cyclopentadienyl)-tri-p.-hydridonickeltri-, 26 363 H4N, Hydrazine ruthenium(II) complexes, 26 72 H40 20sjCi , Osmium, dodecacarbonyl-tetra- x-hydrido-te/rahedro-tetra-,... 

Two (cyclopentadienyl)bis(phosphine)ruthenium chloride complexes have been investigated the nonlinearities are low. These results have been used in conjunction with measured nonlinearities of acetylenes and acetylide complexes to demonstrate that values for the latter are not simply the sum of the molecular components (see earlier). An example of a metal... 

An interesting synthesis of the cyclopentadienyl bisphosphine ruthenium nitrosyl complex 9 involves the thermal displacement of both phenyl groups from (i75-C5H5)Ru(NC))PIi2 (8) with a chelating diphosphine [Eq. (6)] (72). Infrared data indicate that the nitrosyl ligand is linear (3 e ... 

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)]. 

In contrast to the above ruthenium(O) complexes, the reaction of the Ru(II) complex 13, bearing a cyclopentadienyl (Gp) ligand, with electronically neutral phenyl-acetylene gave rise to the coordinatively unsaturated ruthenacyde 14 (Scheme 4.4) [20]. On the basis of X-ray structural analysis, the original authors claimed that 14 is the first formally 18-electron rathenmm(ll)-metallacYclopentatrwne. In accordance with this claim, the NMR resonance corresponding to the metal-carbene a car-... 

For aldol and Michael reaction of nitriles, cyclopentadienyl ruthenium enolate complexes shows catalytic activity. The reaction of 2-methylphenylacetonitrile with ethyl acrylate gave the corresponding Michael addition product in 99% yield (Eq. 9.58) [79]... 

Murahashi and Naota studied the reaction mechanism of cyclopentadienyl ruthenium enolate complex-catalyzed aldol and Michael addition reactions [80-82]. This mechanistic study revealed that the cone angle of the tertiary phosphine ligands largely affects the stability of C- and N-bound complexes [80, 82], Thus, ligation of bulky phosphine ligand would favor the N -bound complexes [80]... 

Further examples include homo-, co- and terpolymers of manganese carbonyl, iron carbonyl or cyclopentadienyl, and ruthenium-phosphine complexes [31, 59, 60]. 

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