“Dibutylmagnesium”, a convenient reagent for the synthesis of useful organic magnesium reagents MgA2 including cyclopentadienyls, aryloxides, and amides. Preparation of Zr(C5H5)Cl3. X-ray structure of [{μ-N(SiMe)3C6H4N}(SiMe3)-o(OEt2)]2

Duff, Alan W.; Hitchcock, Peter B.; Läppert, Michael F.; Taylor, Richard G.; Segal, John A.

doi:10.1016/0022-328x(85)80298-9

Cited by 100 publications

(14 citation statements)

References 17 publications

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“…Synthesis and Physical Properties. The starting metallocenes, Cp‘ ‘ 2 UCl 2 and Cp ⧧ 2 UCl 2 , were prepared by the reaction of UCl 4 with Cp‘ ‘ 2 Mg or Cp ⧧ 2 Mg in diethyl ether, followed by crystallization from hexane as gold or dark red needles, respectively, in yields from 50 to 80%. Cp‘ ‘ 2 UCl 2 was prepared previously by the reaction of Cp‘ ‘Li and UCl 4 in tetrahydrofuran (thf) …”

Section: Resultsmentioning

confidence: 99%

Preparation, Solution Behavior, and Solid-State Structures of (1,3-R₂C₅H₃)₂UX₂, Where R Is CMe₃or SiMe₃and X Is a One-Electron Ligand

et al. 1999

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High-yield preparations of the uranium metallocenes [1,3-(Me3Si)2C5H3]2UCl2 (Cp‘ ‘2UCl2) and [1,3-(Me3C)2C5H3]2UCl2 (Cp⧧ 2UCl2) have been developed from the reaction of UCl4 and the corresponding magnesocenes Cp‘ ‘2Mg and Cp⧧ 2Mg in diethyl ether. The chloride ligands can be exchanged with either Me3SiBr or Me3SiI to give the uranium metallocene bromides or iodides. The fluorides were prepared by the reaction of BF3·OEt2 with Cp‘ ‘2U(NMe)2, Cp⧧ 2U(OMe)2, or Cp⧧ 2UMe2. The crystal structures of Cp‘ ‘2UCl2, Cp⧧ 2UCl2, Cp‘ ‘2UMe2, Cp⧧ 2UF2, and dimeric (Cp‘ ‘2UF2)2 are reported. The idealized symmetry of the monomers Cp‘ ‘2UX2 and Cp⧧ 2UCl2 is C 2 v when X is F, Cl, or Br and C 2 when X is I or Me; in the dimer, the idealized symmetry is C i . This preference is rationalized by intramolecular and intermolecular steric effects. The solution ring conformations and intramolecular exchange processes have been studied by variable-temperature 1H NMR spectroscopy. In all cases, the low-temperature limiting spectra are consistent with the idealized symmetry observed in the solid state.

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Section: Resultsmentioning

confidence: 99%

Preparation, Solution Behavior, and Solid-State Structures of (1,3-R₂C₅H₃)₂UX₂, Where R Is CMe₃or SiMe₃and X Is a One-Electron Ligand

et al. 1999

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“…Dicyclopentadiene and methylcyclopentadiene dimer were cracked under nitrogen and stored at −70 °C prior to use. Magnesocene was prepared as described in the literature. , 1,1‘-Dimethylmagnesocene and bis(1,2,4-trimethylcyclopentadienyl)magnesium were prepared in the same manner from the corresponding methyl-substitued cyclopentadienes. Tris(1,2,3,4-tetramethylcyclopentadienyl)aluminum was prepared as described previously …”

Section: Methodsmentioning

confidence: 99%

Regarding the Structures and Fluxionality of Tricyclopentadienylaluminum Compounds

et al. 1997

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X-ray crystallographic studies, low-temperature X H and 13C NMR studies, and 27Al NMR studies of a series of homoleptic tricyclopentadienylalum inum compounds [(CßHs^Al (1 ), (MeCßHJsAl (2 ), ( l,2 ,4 -Me3C5H2)3Al (3), ( l , 2 ,3 ,4*Me4C5H )3Al (4)] are reported along w ith ab initio calculations on model cyclopentadienylaluminum compounds. The ring-coordination geometries exhibited by the tricyclopentadienylaluminum compounds in the solid state vary with the number of methyl substituents on the cyclopentadienyl rings. The X-ray crystal structure of compound 1 revealed two unique m olecules in the unit cell, one w ith an {rf, rji'5, rf3} combination of ring geometries and the other w ith an {t/2, j/1* 6, rj1} combination of ring-coordination geometries. In the crystal structure of compound 3, one cyclopentadienyl ring is coordinated rf to the aluminum while the other two rings are if. Compound 4 exhibits monohapto coordination of all three tetram ethyl-substituted cyclopentadienyl rings in the solid state. These compounds are highly fluxional in solution and exhibit averaged 1H and 13C NMR spectra in the fast-exchange limit at temperatures as low as -1 1 0 °C. This behavior is explained by the ab initio calculations on model cyclopentadienylalum inum compounds which reveal almost negligible (1 -2 kcal/mol) energy differences betw een different ring hapticities (i;1, rf, rf, rf). Introduction «The cyclopentadienyl ligand is probably best known for its pentahapto-coordination geometiy with transition metals. In the absence of accessible d orbitals, jr-type interactions are weaker, and deviation from 775-geometry by "ring slippage" is often observed. These "ringslipped" (rj1, rf¡ if) structures are more commonly observed among the cyclopentadienyl-main-groupmetal compounds.1" 3 Along with these ring-slipped geometries, cyclopentadienyl compounds of the maingroup elements exhibit varying degrees of fluxionality. Two different sigmatropic processes have been identified experimentally for a-bonded (rj1) species, a 1 ,2-hydrogen shift and a 1,2-shift of the main-group element.4 De tailed mechanistic information on these systems has been obtained, where possible, with the help of variable temper ature NMR techniques.In the case of aluminum, rearrangements are too fast at accessible temperatures to be monitored by NMR. Moreover, equilibrium structures are frequently not rf but ?;L5, rf, or rf> which complicates the discussion of "the sigmatropic process". Nevertheless, it has gener ally been assumed, by extrapolation from experimen tally characterizable systems, that a similar "ringwhizzing"5-8 mechanism is responsible for the dynamic behavior observed in the X H and 13C NMR spectra of cyclopentadienylaluminum compounds. Gas-phase elee-

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“…The Cp* moiety turns out to be an advantageous leaving group being cleanly split off by hydrogenolysis. Important other alloy components, being notoriously difficult to introduce by simple salt reduction, such as Mg, Zn, and Si, may thus as well be applicable via [MgCp* 2 ], [ZnCp* 2 ], and [SiCp* 2 ] as precursors. Just to give an inspiring example, we like to cite the unusual molecular SiAl 14 cluster, [(Cp*Al) 6 (SiAl 8 )], being obtained by employing [SiCp* 2 ] as the Si source .…”

Section: Discussionmentioning

confidence: 99%

Nanometallurgy of Colloidal Aluminides: Soft Chemical Synthesis of CuAl₂ and α/β-CuAl Colloids by Co-Hydrogenolysis of (AlCp*)₄ with [CpCu(PMe₃)]

et al. 2006

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In this work, we present a novel soft chemical synthesis to aluminum nanoparticles based on the hydrogenolysis of the metastable organoaluminum (I) compound (AlCp*)4 (1) in mesitylene at 150 °C and 3 bar H2. Aiming at the development of a general wet-chemical, nonaqueous route to M/E intermetallic nanophases (E = Al, Ga, In), we studied the co-hydrogenolysis of 1 with [CpCu(PMe3)] (2) as the model case aiming at Cu/Al alloyed nanoparticles. One equivalent of 1 combined with 2 equiv of 2 yields the nanocrystalline intermetallic θ-CuAl2 phase (Cu0.33Al0.67), as revealed by elemental analysis, powder X-ray diffraction, transmission electron microscopy (TEM), and energy-dispersive X-ray analysis. The obtained Cu0.33Al0.67 material was also characterized by the 27Al Knight Shift resonance. Alloy particles Cu1 - x Al x (0.10 ≤ x ≤ 0.50), typically 15 ± 5 nm (TEM) in size, are accessible as colloidal solutions by variation of the molar ratio of 1 and 2 and by the addition of poly(2,6-dimethyl-1,4-phenylene oxide) during hydrogenolysis. The 27Al NMR Knight Shift resonance moves to high field starting form the value of 1639 ppm for pure nano-aluminum particles to 1486 ppm of Cu0.33Al0.67, reaching 1446 ppm for Cu0.50Al0.50, and was not detectable for Al contents below 50%. Upon oxidation (controlled exposure to the ambient), a selective oxidation of the Al component, presumably forming core−shell structured Al2O3@Cu1 - y Al y (0.10 ≤ y ≤ 0.50) particles, was studied by UV−vis spectroscopy, 27Al magic-angle spinning NMR, and X-ray photoelectron spectroscopy. The Al content can be freely adjusted and lowered down to about 15 atom % (Cu0.85Al0.15) without oxidizing the Cu(0) core.

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“Dibutylmagnesium”, a convenient reagent for the synthesis of useful organic magnesium reagents MgA2 including cyclopentadienyls, aryloxides, and amides. Preparation of Zr(C5H5)Cl3. X-ray structure of [{μ-N(SiMe)3C6H4N}(SiMe3)-o(OEt2)]2

Cited by 100 publications

References 17 publications

Preparation, Solution Behavior, and Solid-State Structures of (1,3-R₂C₅H₃)₂UX₂, Where R Is CMe₃or SiMe₃and X Is a One-Electron Ligand

Preparation, Solution Behavior, and Solid-State Structures of (1,3-R₂C₅H₃)₂UX₂, Where R Is CMe₃or SiMe₃and X Is a One-Electron Ligand

Regarding the Structures and Fluxionality of Tricyclopentadienylaluminum Compounds

Nanometallurgy of Colloidal Aluminides: Soft Chemical Synthesis of CuAl₂ and α/β-CuAl Colloids by Co-Hydrogenolysis of (AlCp*)₄ with [CpCu(PMe₃)]

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“Dibutylmagnesium”, a convenient reagent for the synthesis of useful organic magnesium reagents MgA2 including cyclopentadienyls, aryloxides, and amides. Preparation of Zr(C5H5)Cl3. X-ray structure of [{μ-N(SiMe)3C6H4N}(SiMe3)-o(OEt2)]2

Cited by 100 publications

References 17 publications

Preparation, Solution Behavior, and Solid-State Structures of (1,3-R2C5H3)2UX2, Where R Is CMe3or SiMe3and X Is a One-Electron Ligand

Preparation, Solution Behavior, and Solid-State Structures of (1,3-R2C5H3)2UX2, Where R Is CMe3or SiMe3and X Is a One-Electron Ligand

Regarding the Structures and Fluxionality of Tricyclopentadienylaluminum Compounds

Nanometallurgy of Colloidal Aluminides: Soft Chemical Synthesis of CuAl2 and α/β-CuAl Colloids by Co-Hydrogenolysis of (AlCp*)4 with [CpCu(PMe3)]

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Preparation, Solution Behavior, and Solid-State Structures of (1,3-R₂C₅H₃)₂UX₂, Where R Is CMe₃or SiMe₃and X Is a One-Electron Ligand

Preparation, Solution Behavior, and Solid-State Structures of (1,3-R₂C₅H₃)₂UX₂, Where R Is CMe₃or SiMe₃and X Is a One-Electron Ligand

Nanometallurgy of Colloidal Aluminides: Soft Chemical Synthesis of CuAl₂ and α/β-CuAl Colloids by Co-Hydrogenolysis of (AlCp*)₄ with [CpCu(PMe₃)]