Halide, hydride, alkyl, and dinitrogen complexes of bis(pentamethylcyclopentadienyl)hafnium

Roddick, Dean M.; Fryzuk, Michael D.; Seidler, Paul; Hillhouse, Gregory L.; Bercaw, John E.

doi:10.1021/om00120a017

Cited by 115 publications

(94 citation statements)

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“…1 was also prepared in 33 % yield from the reaction of Cp* 2 HfCl 2 and BuLi, as described in ref. [22] . 1 Isolation of 2 and 3: Samples of 2 and 3 were obtained from the non-volatile organometallic residue of the fluorocarbon reduction reactions.…”

Section: Methodsmentioning

confidence: 99%

“…Comparison of 1 H NMR spectroscopic data to known literature values for 1 confirmed that it was indeed the expected product. [22] (3)…”

Section: Synthesis Of Cp* 2 Hfh 2 and Its Fluoro Derivativesmentioning

confidence: 99%

“…The long reaction time required for a reasonable degree of conversion can be avoided using the method reported by Bercaw, in which 1 was made directly from Cp* 2 HfCl 2 using n-butyllithium under hydrogen, a process that afforded the dried, isolated product in roughly 3 d. [22] Due to the sensitive nature of the starting hafnium complex, [23] great care was taken to prevent air and moisture from being present in any reaction using 1 as a starting material. To this end, all solvents must first be dried with purple sodium/benzophenone ketyl and then over green titanocene, formed from the reaction of Cp 2 TiCl 2 and zinc dust in the solvent of interest.…”

Section: Synthesis Of Cp* 2 Hfh 2 and Its Fluoro Derivativesmentioning

confidence: 99%

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Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*₂HfH₂

2007

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Section: Methodsmentioning

confidence: 99%

“…Comparison of 1 H NMR spectroscopic data to known literature values for 1 confirmed that it was indeed the expected product. [22] (3)…”

Section: Synthesis Of Cp* 2 Hfh 2 and Its Fluoro Derivativesmentioning

confidence: 99%

Section: Synthesis Of Cp* 2 Hfh 2 and Its Fluoro Derivativesmentioning

confidence: 99%

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Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*₂HfH₂

2007

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“…Thus, (C 5 9 The hafnium metallocene behaved similarly, although it was noted that the cis-and trans-endiolates are formed and the cis-trans ratio was always greater than unity. 10 The amide hydride, [(Me 3 C) 3 SiN(H)] 3 ZrH, reacts with excess CO to yield the cis-enediolate, {[(Me 3 C) 3 SiN(H)] 3 Zr} 2 (μ-OCH=CHO). 11 In this case, an η 2 -formaldehyde complex {[(Me 3 C) 3 SiN(H)] 3 Zr} 2 (μ-OCH 2 ) was isolated and shown to be an intermediate, since it reacts with CO to yield the enediolate by way of the CO insertion species, {[(Me 3 C) 3 SiN(H)] 3 Zr} 2 (μ-OCH 2 CO), which was detected spectroscopically.…”

Section: Introductionmentioning

confidence: 99%

Reactions of Monomeric [1,2,4-(Me₃C)₃C₅H₂]₂CeH and CO with or without H₂: An Experimental and Computational Study

et al. 2007

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Abstract:Addition of CO to [1,2,4-(Me 3 C) 3 C 5 H 2 ] 2 CeH, Cp' 2 CeH, in toluene yields the cis-(Cp' 2 Ce) 2 (μ-OCHCHO), in which the cis-enediolate group bridges the two metallocene fragments. The cis-enediolate quantitatively isomerizes intramolecularly to the trans-enediolate in C 6 D 6 at 100°C over seven months. When the solvent is pentane, Cp' 2 Ce(OCH 2 )CeCp' 2 forms, in which the oxomethylene group or the formaldehyde dianion bridges the two metallocene fragments. The cis-enediolate is suggested to form by insertion of CO into the Ce-C bond of 1 Cp' 2 Ce(OCH 2 )CeCp' 2 generating Cp' 2 CeOCH 2 COCeCp' 2 . The stereochemistry of the cisenediolate is determined by a 1,2-hydrogen shift in the OCH 2 CO fragment that has the OC(H 2 ) bond anti-periplanar relative to the carbene lone pair. The bridging oxomethylene complex reacts with H 2 , but not with CH 4 , to give Cp' 2 CeOMe, which is also the product of the reaction between Cp' 2 CeH and a mixture of CO and H 2 . The oxomethylene complex reacts with CO to give the cis-enediolate complex. DFT calculations on C 5 H 5 model metallocenes show that the reaction of Cp 2 CeH with CO and H 2 to give Cp 2 CeOMe is exoergic by 50 kcal mol -1 . The net reaction proceeds by a series of elementary reactions that occur after the formyl complex, Cp 2 Ce(η 2 -CHO), is formed by further reaction with H 2 . The key point that emerges from the calculated potential energy surface is the bifunctional nature of the metal formyl in which the carbon atom behaves as a donor and acceptor. Replacing H 2 by CH 4 increases the activation energy barrier by 17 kcal mol -1 .

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“…Another related rule was to avoid what you did while you were a postdoctoral fellow. For me that meant staying away from zirconium and hafnium hydrides stabilized by pentamethylcyclopentadienyl ligands (4). As it turns out I probably ended up disobeying both of these rules, but I'm getting ahead of myself.…”

Section: Introductionmentioning

confidence: 99%

The 1992 Alcan Award Lecture Excursions around the periodic table: ligand design in inorganic chemistry

Fryzuk¹

1992

Can. J. Chem.

113

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An overview is given on the strategy used to come up with the design of a new type of ligand that is appropriate for coordination to both the late metals and the early metals. The coordination chemistry of the potentially tridentate ligand −N(SiMe2CH2PR2)2 is developed starting with the Ni triad and then the heavier members of group 9, namely rhodium and iridium. It is with iridium that reactive fragments such as methylene and vinylidene have been stabilized and their chemistry examined. Extension to groups 3, 4, and the lanthanides is also discussed. With these elements, phosphine coordination imparts new reactivity patterns such as alkane elimination with group 3 and dinitrogen activation with group 4. In addition, the side-on binding mode for N2 attached to a dinuclear zirconium system is also presented.

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Halide, hydride, alkyl, and dinitrogen complexes of bis(pentamethylcyclopentadienyl)hafnium

Cited by 115 publications

References 0 publications

Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*₂HfH₂

Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*₂HfH₂

Reactions of Monomeric [1,2,4-(Me₃C)₃C₅H₂]₂CeH and CO with or without H₂: An Experimental and Computational Study

The 1992 Alcan Award Lecture Excursions around the periodic table: ligand design in inorganic chemistry

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Halide, hydride, alkyl, and dinitrogen complexes of bis(pentamethylcyclopentadienyl)hafnium

Cited by 115 publications

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Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*2HfH2

Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*2HfH2

Reactions of Monomeric [1,2,4-(Me3C)3C5H2]2CeH and CO with or without H2: An Experimental and Computational Study

The 1992 Alcan Award Lecture Excursions around the periodic table: ligand design in inorganic chemistry

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Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*₂HfH₂

Activation of Aromatic, Aliphatic, and Olefinic Carbon–Fluorine Bonds Using Cp*₂HfH₂

Reactions of Monomeric [1,2,4-(Me₃C)₃C₅H₂]₂CeH and CO with or without H₂: An Experimental and Computational Study