σ,-Ferrocenyl-komplexe des rutheniums

Herberhold, Max; Feger, Wolfgang; Kölle, Ulrich

doi:10.1016/0022-328x(92)85065-5

Cited by 16 publications

(4 citation statements)

References 22 publications

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“…Indeed, the average Ru−C σ bond distance (2.09 Å) is similar to those reported for other ruthenium C sp 2 single bonds 12,19d and is significantly larger than those in ruthenium carbenes (∼1.8−1.9 A) much further downfield than the corresponding signal observed for 2 , which exhibits a chemical shift (96.8 ppm) that is in agreement with model systems …”

Section: Resultssupporting

confidence: 82%

“…While, in the absence of pertinent bond strength data, simple initial homolytic cleavage of a Ru−C σ bond followed by a rapid rearrangement to 16 and ring closure (“biradical” mechanism) cannot be ruled out, it appears unlikely on consideration of literature data which suggest a DH °(Ru−C sp 2 ) closer to 40 kcal mol -1 or more. , Moreover, a crude thermochemical estimate of bond strengths, assuming DH °(Ru−C sp 2 ) = 30 kcal mol -1 for 2 (from the above Δ H ⧧ for 2 → 1 ), DH °(Ru−Ru) ≈ 35 kcal mol -1 {a value extrapolated for [(η 5 -C 5 H 5 )Ru(CO) 2 ] 2 from measured data for related (CpM) 2 complexes}, and the enthalpy change ( 2 → 1 ) ∼ −30 kcal mol -1 (vide supra), would provide a Cp−Cp bond strength of ∼55 kcal mol -1 , intuitively unreasonably low . On the other hand, the positive and, except for 15 , large Δ S ⧧ values indicate substantial disorder in the transition state, certainly consistent with a biradical pathway …”

Section: Resultsmentioning

confidence: 99%

“…13 Alkylidene carbons on ruthenium have also been reported to exhibit 13 C NMR resonances at ∼250 ppm, 13 much further downfield than the corresponding signal observed for 2, which exhibits a chemical shift (96.8 ppm) that is in agreement with model systems. 14 Even more remarkable than the photoinduced dinuclear oxidative addition reaction of 1 that produced 2 is its facile thermal reversal. This process occurred at moderate temperatures (>65 °C) in solution, allowing for the ready recording of kinetic data (vide infra).…”

Section: Resultsmentioning

confidence: 99%

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Photochemistry of (Fulvalene)tetracarbonyldiruthenium and Its Derivatives: Efficient Light Energy Storage Devices

et al. 1997

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Broad-band irradiation (λ max ) 350 nm) of FvRu 2 (CO) 4 (1, Fv ) η 5 :η 5 -bicyclopentadienyl) resulted in rapid isomerization to colorless (µ 2 -η 1 :η 5 -cyclopentadienyl) 2 Ru 2 (CO) 4 (2) in a novel process involving a formal dinuclear oxidative addition to a C-C bond. The product reverted to 1 upon heating in solution or in the solid state, under the latter conditions with an enthalpy change of -29.8 (1.5) kcal mol -1 . Mechanistic studies with a mixture of 1 and 1-d 8 revealed the absence of label scrambling, pointing to intramolecular pathways. The quantum yield (0.15) was unaffected by the presence of CCl 4 , and no chlorination products were observed under these conditions. Irradiation of solutions of 1 or 2 with 300 nm light provided Fv(µ 2 -η 1 :η 5 -cyclopentadienyl) 2 Ru 4 (CO) 6 (6) or, in the presence of alkynes, the adducts FvRu 2 (CO) 3 (RCCR) (8-10, R ) H, C 6 H 5 , CO 2 CH 3 ). Heating 1 and PR 3 (R ) CH 2 CH 3 , CH 3 , or OCH 3 ) yielded FvRu 2 (CO) 3 (PR 3 ) (12-14), in which a fluxional process occurs characterized by intramolecular terminal to bridging carbonyl exchange. While 12 and 13 were inert, compound 14 rapidly and reversibly afforded the P(OCH 3 ) 3 -substituted analog of 2 (15) upon irradiation with UV light. The two diastereomeric 3,3′-di-tert-butyl-substituted fulvalene analogs of 1 (19) underwent the same reaction sequence with complete retention of stereochemistry, via the diastereomeric photoproducts 20. A double regiochemical labeling experiment proceeded with retention of connectivity and stereochemistry. A concerted mechanism for the photoisomerization is consistent with the experimental observations, but a biradical pathway cannot be ruled out. Kinetic data for the isomerizations of 2, 15, 20a, and 20b to their respective metal-metal-bonded Fv precursors were determined. The entropies of activation (+7 to +21 eu) suggested a disordered transition state. A sequence involving reversible CO loss was ruled out through a crossover experiment with 2-13 CO. Kinetic and labeling experiments point to a change in mechanism when the thermal reversion of 2 to 1 was run under CO (∼1 atm). The occurrence of ligand-induced C-C coupling was indicated through studies of the reactivity of 2 with P(CH 3 ) 3 . Photoisomer 2 reacts with excess CCl 4 to give FvRu 2 (CO) 4 Cl 2 ) by yet another mechanism. As in the potoisomerization of 1, the thermal reversion of 2 may follow a concerted pathway, although biradical intermediates cannot be excluded.(51) This problem is intractable by simple analysis, because (1) Ru has seven natural isotopes, generating 16 readily observable peaks in the mass spectra of 1 and 2, (2) 13 CO enrichment of 2-( 13 CO) was not complete, (3) the commercial 13 CO used (Cambridge Isotope Laboratories, Inc.) contains approximately 10% 18 O, and (4) natural abundance 13 C in the samples had to be considered. We thank Mr. D. Peterson and Professor J. Rice, UCB Department of Statistics for their help in solving it.(52) Hoffmann, R.; Minkin, V. I.; Carpenter, B. K.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Photochemistry of (Fulvalene)tetracarbonyldiruthenium and Its Derivatives: Efficient Light Energy Storage Devices

et al. 1997

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“…Treatment of [RuCl(Fc)(CO)(r|-C 6 Me 6 )] with the appropriate organolithium reagent gives [Ru(R)(Fc)(CO)(Ti-C 6 Me 6 )] (R = Bu n , p-Tol). 167 The relationship between a-alkyls and alkene complexes in (arene)osmium chemistry is particularly close. Treatment of [OsMe 2 (CO)(r|-arene)] with [Ph 3 C]PF 6 gives the hydrido(ethene) complex [OsH(r|-C 2 H 4 )(CO)(r|-arene)]PF 6 (arene = C 6 H 6 , C 6 H 3 Me 3 ); this reaction probably proceeds by initial hydride abstraction from one of the methyl groups, migration of the other methyl group to the Os=CH 2 moiety thus formed, and (3- …”

Section: Hydrides and Alkyls Containing No Other Rc-acceptor Ligandsmentioning

confidence: 98%

Complexes of Ruthenium and Osmium Containing η2–η6 Hydrocarbon Ligands: (iii) Complexes Containing Six-, Seven- and Eight-membered Rings

Bennett

1995

Comprehensive Organometallic Chemistry II

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Ferrocene Compounds Containing Heteroelements

Herberhold¹

1994

Ferrocenes

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σ,-Ferrocenyl-komplexe des rutheniums

Cited by 16 publications

References 22 publications

Photochemistry of (Fulvalene)tetracarbonyldiruthenium and Its Derivatives: Efficient Light Energy Storage Devices

Photochemistry of (Fulvalene)tetracarbonyldiruthenium and Its Derivatives: Efficient Light Energy Storage Devices

Complexes of Ruthenium and Osmium Containing η2–η6 Hydrocarbon Ligands: (iii) Complexes Containing Six-, Seven- and Eight-membered Rings

Ferrocene Compounds Containing Heteroelements

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