Dioxygen Activation at [OsCl(dcpe)2]+Gives [OsCl(O)(dcpe)2]+, the First Stable Oxo Complex of Osmium(IV)

Barthazy, Peter; Wörle, Michael; Mezzetti, Antonio

doi:10.1021/ja982736q

Cited by 18 publications

(14 citation statements)

References 42 publications

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“…On the basis of this observation, and precedents of asymmetric epoxidation of terminal olefins catalyzed by platinum complexes containing chiral diphosphines, we suspect that the lack of chiral induction with 3a , b is due to the pseudo -C s -symmetry in the oxo intermediate [RuCl(O)(P−P*) 2 ] + . The latter species is the putative oxene-transfer reagent based on previous mechanistic studies 11a and on the isolation of the osmium analogue trans -[OsCl(O)(dcpe) 2 ] + (dcpe = 1,2-bis(dicyclohexylphosphino)ethane). , However, as partial oxidative degradation of the P−P* ligand occurs, the lack of asymmetric induction could also be due to the formation of an achiral complex.…”

Section: Resultsmentioning

confidence: 99%

Five-Coordinate [RuCl(P−P*)₂]⁺Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

et al. 1999

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The six-coordinate complexes trans-[RuCl2(P−P*)2] (P−P* = (S,S)-1,2-bis(1-naphthylphenylphosphino)ethane (bnpe), 2a; (S,S)-2,3-bis(diphenylphosphino)butane (chiraphos), 2b) have been prepared and structurally characterized. The X-ray studies of 2a,b show non-C 2-symmetric conformations of the substituents at the PPh2 groups in a highly crowded octahedral environment. Complexes 2a,b react with Tl[PF6] in CH2Cl2 to give the corresponding monochloro, cationic derivatives [RuCl(P−P*)2]PF6 (P−P* = bnpe, 3a; chiraphos, 3b). The bnpe derivative 3a is five-coordinate both in the solid state (by X-ray investigation) and in solution (by 31P NMR spectroscopy). The chiraphos analogue 3b apparently dimerizes in solution, depending on the solvent (CDCl3 or CD2Cl2) and on the concentration. Complexes 3a,b catalyze the decomposition of ethyl diazoacetate to give, in the presence of styrene, the corresponding cyclopropanation products with enantioselectivity up to 35% ee and E/Z ratios of about 55:45. Complexes 3a,b also catalyze the epoxidation of unfunctionalized olefins with iodosyl benzene as the primary oxidant. High olefin conversions and fair selectivity for the epoxide are observed, but both 3a and 3b give racemic epoxide.

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Section: Resultsmentioning

confidence: 99%

Five-Coordinate [RuCl(P−P*)₂]⁺Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

et al. 1999

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“…Thus, the Ru (12) and NHC = IMe 4 (13) from reactions performed in pyridine, while the Ru (14) was produced upon reaction of 2 with dioxygen in CD 2 Cl 2 . [5,38] The X-ray crystal structures of these three compounds are provided in the Supporting Information.…”

Section: Reactivity Of 2 and 3 With Omentioning

confidence: 99%

The Influence of N‐Heterocyclic Carbenes (NHC) on the Reactivity of [Ru(NHC)₄H]⁺ With H₂, N₂, CO and O₂

Burling

Häller

Mas‐Marzá

et al. 2009

Chemistry A European J

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The five-coordinate ruthenium N-heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr(2)Me(2))(4)H][BAr(F) (4)] (1; IiPr(2)Me(2)=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene; Ar(F)=3,5-(CF(3))(2)C(6)H(3)), [Ru(IEt(2)Me(2))(4)H][BAr(F) (4)] (2; IEt(2)Me(2)=1,3-diethyl-4,5-dimethylimidazol-2-ylidene) and [Ru(IMe(4))(4)H][BAr(F) (4)] (3; IMe(4)=1,3,4,5-tetramethylimidazol-2-ylidene) have been synthesised following reaction of [Ru(PPh(3))(3)HCl] with 4-8 equivalents of the free carbenes at ambient temperature. Complexes 1-3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about delta -41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe(4))(4)(MeCN)H][BAr(F) (4)], 4. The reactivity of 1-3 towards H(2) and N(2) depends on the size of the N-substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H(2) and N(2) only at low temperature and incompletely, while 3 affords [Ru(IMe(4))(4)(eta(2)-H(2))H][BAr(F) (4)] (7) and [Ru(IMe(4))(4)(N(2))H][BAr(F) (4)] (8) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1-3 to give [Ru(NHC)(4)(CO)H][BAr(F) (4)] (9-11). Addition of O(2) to solutions of 2 and 3 leads to rapid oxidation, from which the Ru(III) species [Ru(NHC)(4)(OH)(2)][BAr(F) (4)] and the Ru(IV) oxo chlorido complex [Ru(IEt(2)Me(2))(4)(O)Cl][BAr(F) (4)] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO >> O(2) > N(2) > H(2).

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“…The coordination of dioxygen to transition metals and organometallic complexes is of significant interest, given dioxygen’s essential role in aerobic life forms and potential as an environmentally benign terminal oxidant. − For 1:1 metal–dioxygen complexes, one of two possible binding approaches is typically observed: end-on (η 1 ) or side-on (η 2 ). ,− These can be further differentiated as peroxo (O 2 2– ) or superoxo (O 2 – ) complexes depending on the O–O bond lengths and stretching frequencies observed by X-ray crystallography and vibrational spectroscopy, respectively. ,, The more common η 2 -peroxo bonding mode is characterized by longer bond lengths (∼1.4–1.5 Å) and lower stretching frequencies (∼800–930 cm –1 ), ,,,− whereas η 2 -superoxo complexes possess characteristically shorter bond lengths (∼1.2–1.3 Å) and higher stretching frequencies (1050–1200 cm –1 ). ,,,,,− Formally, these two bonding scenarios correspond to differing electronic configurations and charge distributions between the metal fragment and the coordinated dioxygen ligand, resulting from one-electron (superoxo) and two-electron (peroxo) reduction of O 2 , respectively. , …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Cationic Rhodium Peroxo Complexes

et al. 2012

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Mononuclear cationic rhodium complexes of dioxygen have been synthesized and characterized. Crystallographic, spectroscopic, and computational results support the conclusion that these complexes are best described as Rh III {O 2 2− } (rhodium(III) peroxo) complexes, in contrast to recently reported neutral analogues that are best described as Rh I { 1 O 2 } adducts. The nature of the ligand trans to the O 2 ligand is crucial in defining the electronic nature of the RhO 2 bonding. It is determined that π-donor ligands such as the halidesin conjunction with sufficient steric bulkcan stabilize the formation of Rh I { 1 O 2 } adducts, whereas stronger field ligands lead to the stabilization of asymmetric O 2 binding that ultimately favors formation of higher coordinate Rh III peroxo species. The factors that control the relative stabilization of Rh III {O 2 2− } versus Rh I { 1 O 2 } species are related to the well-established Dewar−Chatt−Duncanson model that has been successfully used to describe the bonding in isoelectronic transition-metal alkene complexes. The specific factors that control the stabilization of one electromer (resonance structure) over another are explored and discussed in detail.

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Dioxygen Activation at [OsCl(dcpe)₂]⁺Gives [OsCl(O)(dcpe)₂]⁺, the First Stable Oxo Complex of Osmium(IV)

Cited by 18 publications

References 42 publications

Five-Coordinate [RuCl(P−P*)₂]⁺Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

Five-Coordinate [RuCl(P−P*)₂]⁺Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

The Influence of N‐Heterocyclic Carbenes (NHC) on the Reactivity of [Ru(NHC)₄H]⁺ With H₂, N₂, CO and O₂

Synthesis and Characterization of Cationic Rhodium Peroxo Complexes

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Dioxygen Activation at [OsCl(dcpe)2]+Gives [OsCl(O)(dcpe)2]+, the First Stable Oxo Complex of Osmium(IV)

Cited by 18 publications

References 42 publications

Five-Coordinate [RuCl(P−P*)2]+Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

Five-Coordinate [RuCl(P−P*)2]+Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

The Influence of N‐Heterocyclic Carbenes (NHC) on the Reactivity of [Ru(NHC)4H]+ With H2, N2, CO and O2

Synthesis and Characterization of Cationic Rhodium Peroxo Complexes

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Dioxygen Activation at [OsCl(dcpe)₂]⁺Gives [OsCl(O)(dcpe)₂]⁺, the First Stable Oxo Complex of Osmium(IV)

Five-Coordinate [RuCl(P−P*)₂]⁺Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

Five-Coordinate [RuCl(P−P*)₂]⁺Complexes Containing Chiral Diphosphines: Application in the Asymmetric Cyclopropanation and Epoxidation of Olefins

The Influence of N‐Heterocyclic Carbenes (NHC) on the Reactivity of [Ru(NHC)₄H]⁺ With H₂, N₂, CO and O₂