The tert-butyl peroxide complexes of permethylhafnocene, (.eta.5-C5Me5)2Hf(R)(OOCMe3).  Stoichiometric transformation of alkyl tert-butyl peroxide derivatives to alkoxy tert-butoxides, (.eta.5-C5Me5)2Hf(OR)(OCMe3)

Asselt, A. Van; Santarsiero, Bernard D.; Bercaw, John E.

doi:10.1021/ja00286a044

Cited by 40 publications

(28 citation statements)

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“…Rate limiting homolysis is further supported by the small positive ΔS ‡ values for the decompositions of 1, 3, 4, and 5 (Table 3). A radical chain mechanism is not likely because of the reproducible simple firstorder kinetic behavior and because the decomposition of 1 is little affected by the oxidative and reductive radical traps CBr 4 and n Bu 3 SnH ( 9 In the presence of 9,10-dihydroanthracene, the latter compound converts to Cp* 2 Hf (C 6 H 5 )OH and t BuOH. 9 The barrier for homolysis in Cp* 2 Hf(OO t Bu)Cl is ΔH ‡ = 22.6 kcal mol −1 , similar to what is seen for 1-5.…”

Section: Pathway For Decomposition Of Peroxide Complexes: O-o Bondmentioning

confidence: 99%

“…Homolytic O-O bond cleavage has previously been found in the decomposition of (5) Cp* 2 Hf(OO t Bu)R compounds. 9 The lack of reactivity of the Cp 2 Ti(η 1 -OO t Bu)L complexes is attributed to their inability to form the more reactive and accessible η 2 conformer, even with very weakly binding ligands L. A preliminary account of part of this work has appeared. 17…”

Section: Introductionmentioning

confidence: 99%

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Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

2006

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The titanium(IV) alkylperoxide complex Cp 2 Ti(OO t Bu)Cl (1) is formed on treatment of Cp 2 TiCl 2 with NaOO t Bu in THF at −20 °C. Treatment of 1 with AgOTf at −20 °C gives the triflate complex Cp 2 Ti(OO t Bu)OTf (2), which is rapidly converted to the bromide Cp 2 Ti(OO t Bu)Br (3) on addition of n Bu 4 NBr. The X-ray crystal structures of 1 and 3 both show η 1 -OO t Bu ligands. Complex 2 is stable only below −20 °C; 1 H, 13 C, and 19 F NMR spectra suggest that it also contains an η 1 -OO t Bu ligand. Removal of the chloride from 1 with [Ag(Et 2 O) 2 ]BAr' 4 (Ar' = 3,5-(CF 3 ) 2 C 6 H 3 )) yields the etherate complex [Cp 2 Ti(OO t Bu)(OEt 2 )]BAr' 4 (4). Again, coordination of a fourth ligand to the Ti center indicates an η 1 -OO t Bu ligand in 4. These peroxide complexes do not directly oxidize olefins or phosphines. For instance, the cationic etherate complex 4 reacts with excess Et 3 P simply by displacement of the ether to form [Cp 2 Ti(η 1 -OO t Bu)(Et 3 P)]BAr' 4 (5). Compounds 1-5 all decompose by O-O bond homolysis, based on trapping and computational studies. The lack of direct oxygen atom transfer reactivity is likely due to the η 1 coordination of the peroxide and the inability to adopt more reactive η 2 geometry. DFT calculations indicate that the steric bulk of the t Bu group inhibits formation of the hypothetical [Cp 2 Ti(η 2 -OO t Bu)] + species.

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Section: Pathway For Decomposition Of Peroxide Complexes: O-o Bondmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

2006

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“…

Transition-metal alkylperoxo species (M-OOR'; R' denotes alkyl group) are postulated as reactive intermediates in various oxidation reactions ranging from industrial processes to biological systems. [2][3][4][5] Interest in the alkylperoxo complexes of late transition metals is also growing because of their industrial significance and biological relevance. [2][3][4][5] Interest in the alkylperoxo complexes of late transition metals is also growing because of their industrial significance and biological relevance.

…”

mentioning

confidence: 99%

“…[1] The alkylperoxo complexes of d 0 early transition-metal ions (groups [4][5][6], in particular, have attracted much attention, owing to their potential as oxygenating reagents for organic compounds (for example, olefin epoxidation). [1] The alkylperoxo complexes of d 0 early transition-metal ions (groups [4][5][6], in particular, have attracted much attention, owing to their potential as oxygenating reagents for organic compounds (for example, olefin epoxidation).…”

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Structural Characterization and Oxidation Activity of a Nickel(II) Alkylperoxo Complex

et al. 2008

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Transition-metal alkylperoxo species (M-OOR'; R' denotes alkyl group) are postulated as reactive intermediates in various oxidation reactions ranging from industrial processes to biological systems. [1] The alkylperoxo complexes of d 0 early transition-metal ions (groups 4-6), in particular, have attracted much attention, owing to their potential as oxygenating reagents for organic compounds (for example, olefin epoxidation). [2][3][4][5] Interest in the alkylperoxo complexes of late transition metals is also growing because of their industrial significance and biological relevance. [6][7][8] Nickel is recognized as one of the most useful metals in promoting various organic transformation reactions, owing its intrinsic redox properties. Recent developments in the chemistry of nickel dioxygen complexes have shed light on the applicability of nickel species as oxidizing agents. For example, dinuclear nickel(III) bis(m-oxo) compounds exhibit H-abstraction of aliphatic hydrocarbyl species, in a similar fashion to the M 2 (m-O) 2 species of high-valent Fe and Cu. [9] Furthermore, several nickel dioxygen complexes [9b, 10] and peroxide-based catalytic oxidation reactions with nickel complexes [11] have been reported. An nickel(II) alkylperoxo complex, reported by Suzuki and coworkers, was formed by O 2 oxygenation of the alkyl radical center on the metalsupporting ligand, which was itself generated through Habstraction by the Ni 2 (m-O) 2 species. [9a, 12] However, the structure and reactivity of nickel alkylperoxo complexes remains to be studied, to afford an insight into the interaction between nickel compounds and peroxides, the intrinsic reactivity of the resulting nickel peroxo species, and the properties of catalytic intermediates. Herein we report the molecular structure and the oxidizing activity of a nickel(II) alkylperoxo complex, [Ni II (OOtBu)(Tp iPr )] (1; Tp iPr = hydrotris(3,5-di-2-propylpyrazolyl)borate).Compound 1 was synthesized by the dehydrative condensation of a nickel(II) hydroxo complex, [(Ni II Tp iPr ) 2 (m-OH) 2 ] (2, Scheme 1), [13] with a stoichiometric amount of tertbutylhydroperoxide (TBHP). Addition of two equivalents of TBHP at 0 8C to a pentane solution of 2 resulted in an immediate change in the color of the solution, from green to orange, and the appearance of a strong band in the absorption spectrum at around 370 nm (e = 1400 cm À1 m À1 ). The molecular structure of 1 was revealed by single-crystal X-ray diffraction ( Figure 1). The nickel center of 1 is coordinated by three donor nitrogen atoms from the Tp iPr ligand. The Scheme 1. Synthesis and reactions of 1. TBHP = tert-butylhydroperoxide; Tp iPr = hydrotris(3,5-di-2-propylpyrazolyl)borate. Figure 1. The molecular structure of 1, with thermal ellipsoids set at 50 % probability. All hydrogen atoms are omitted for clarity.[*] Prof.

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New Insights into the Mechanism of Hydroperoxide Activation by Investigation of Dynamic Processes in the Coordination Sphere of Seven-Coordinated Molybdenum Peroxo Complexes

Hroch

Gemmecker

Thiel

2000

Eur. J. Inorg. Chem.

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Seven‐coordinated molybdenum oxobisperoxo complexes with chelate nitrogen donors like pyrazolylpyridines are catalysts for the epoxidation of olefins. An NMR spectroscopic and quantumchemical study on the fluxionality of the chelate ligand proves that during this process partial ligand dissociation takes place. This gave rise to a detailed theoretical study on the activation of CH3OOH at the model complex (NH3)2MoO(O2)2 including dissociation of one of the ammonia ligands and proton transfer from the hydroperoxide to one of the peroxo ligands.

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The tert-butyl peroxide complexes of permethylhafnocene, (.eta.5-C5Me5)2Hf(R)(OOCMe3). Stoichiometric transformation of alkyl tert-butyl peroxide derivatives to alkoxy tert-butoxides, (.eta.5-C5Me5)2Hf(OR)(OCMe3)

Cited by 40 publications

References 4 publications

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

Structural Characterization and Oxidation Activity of a Nickel(II) Alkylperoxo Complex

New Insights into the Mechanism of Hydroperoxide Activation by Investigation of Dynamic Processes in the Coordination Sphere of Seven-Coordinated Molybdenum Peroxo Complexes

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The tert-butyl peroxide complexes of permethylhafnocene, (.eta.5-C5Me5)2Hf(R)(OOCMe3). Stoichiometric transformation of alkyl tert-butyl peroxide derivatives to alkoxy tert-butoxides, (.eta.5-C5Me5)2Hf(OR)(OCMe3)

Cited by 40 publications

References 4 publications

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp2TiIV(η1-OOtBu)L]+/0, L = Cl-, OTf-, Br-, OEt2, Et3P

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp2TiIV(η1-OOtBu)L]+/0, L = Cl-, OTf-, Br-, OEt2, Et3P

Structural Characterization and Oxidation Activity of a Nickel(II) Alkylperoxo Complex

New Insights into the Mechanism of Hydroperoxide Activation by Investigation of Dynamic Processes in the Coordination Sphere of Seven-Coordinated Molybdenum Peroxo Complexes

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Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P

Non-Redox-Assisted Oxygen−Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp₂Ti^IV(η¹-OO^tBu)L]^+/0, L = Cl^-, OTf^-, Br^-, OEt₂, Et₃P