Über Metallalkyl- und -aryl-Verbindungen

Weiß, Erwin; Lambertsen, Thomas; Schubert, Bernd; Cockcroft, Jeremy K.

doi:10.1016/0022-328x(88)87066-9

Cited by 37 publications

(12 citation statements)

References 23 publications

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“…These values are similar to those previously reported by Weiss for the structure of [MeK] where K also forms long distance interactions with the Me groups of other units (mean K⋯Me, 3.441 Å) which are significantly elongated when compared to the K-Me distances towards the carbanion (2.447 Å). 26 It should be noted that polymorph of 3 has been previously reported by Purdy, prepared as previously mentioned by reaction of elemental potassium with Zn(CH 2 SiMe 3 ) 3 . Although K is also hepta-coordinated in this structure, it displays welldefined {KZn(CH 2 SiMe 3 } 2 dimeric fragments which interact with neighbouring units through K⋯Me contacts.…”

Section: Solid-state Structuresmentioning

confidence: 74%

New supramolecular assemblies in heterobimetallic chemistry: synthesis of a homologous series of unsolvated alkali-metal zincates

et al. 2014

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Using an interlocking co-complexation approach, a homologous series of unsolvated alkali-metal zincates [MZn(CH2SiMe3)3] (M = Li 1, Na 2, K 3) was prepared by reacting equimolar amounts of Zn(CH2SiMe3)2 with the relevant alkali-metal alkyl M(CH2SiMe3) employing non-coordinating hexane as a solvent. X-ray crystallographic studies reveal that these heterobimetallic compounds exhibit unprecedented supramolecular assemblies made up exclusively of a three-fold combination of M-CH2, Zn-CH2 and M···Me interactions. Revealing an important alkali-metal effect, 1 displays a linear chain structure; whereas 2 and 3 form much more intricate 3D and 2D coordination networks respectively. Shedding new light into the formation of these solvent-free zincates, DFT calculations indicate that the infinite degree of aggregation observed in 1-3 plays a major role in thermodynamically driving the co-complexation reactions of their homometallic precursors. NMR spectroscopic studies suggest that in C6D6 solution 1-3 exist as discrete contacted ion-pair species, where the alkali-metal is partially solvated by molecules of deuterated solvent. The supramolecular assemblies of 1-3 can be easily deaggregated by adding the polydentate N-donors PMDETA (N,N,N',N'',N''-pentamethyldiethylenetriamine) or TMEDA (N,N,N',N'-tetramethylethylenediamine), affording monomeric [(PMDETA)LiZn(CH2SiMe3)3] (4) and [(TMEDA)2NaZn(CH2SiMe3)3] (5).

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Section: Solid-state Structuresmentioning

confidence: 74%

New supramolecular assemblies in heterobimetallic chemistry: synthesis of a homologous series of unsolvated alkali-metal zincates

et al. 2014

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“…CH 3 Cl (>99.5%, Aldrich) was used as received without further purification. CH 2 DCl and CHD 2 Cl were synthesized from CH 2 DOH (>98%, Cambridge Isotopes) and CHD 2 OH (>98%, Cambridge Isotopes), respectively, according to the two-step procedure reported by Weiss et al In the first step, the alcohol (25 mmol, 1 mL) was added slowly to POCl 3 (55 mmol, 5 mL; >98%, Fluka) at room temperature under magnetic stirring and reflux for about 1 h during which some HCl was formed. The second step was carried out in a closed system connected to a vacuum line: the alcohol/POCl 3 solution was added slowly to PCl 5 (34 mmol, 7 g; >98%, Fluka) at room temperature under reflux and magnetic stirring.…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

Study of the Carbon-13 and Deuterium Kinetic Isotope Effects in the Cl and OH Reactions of CH₄ and CH₃Cl

2005

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Relative rate experiments have been carried out for three isotopologues of chloromethane and their reactions with Cl atoms and OH radicals. The OH and Cl reaction rates of CH2DCl and CHD2Cl were measured by long-path FTIR spectroscopy relative to CH3Cl at 298+/-2 K and 1013+/-10 hPa in purified air. The FTIR spectra were fitted using a nonlinear least squares spectral fitting method including measured high-resolution infrared spectra as references. The relative reaction rates defined by alpha=klight/kheavy were determined to be kOH+CH3Cl/kOH+CH2DCl=1.41+/-0.05, kOH+CH3Cl/kOH+CHD2Cl=2.03+/-0.05, kCl+CH3Cl/kCl+CH2DCl=1.42+/-0.04, and kCl+CH3Cl/kCl+CHD2Cl=2.27+/-0.04. The carbon-13 and deuterium kinetic isotope effects in the OH and Cl reactions of CH3Cl were investigated further using variational transition state theory, and the results were compared to similar calculations performed for the CH4+OH/Cl reaction systems. The calculations show that the order of magnitude difference for the carbon-13 kinetic isotope effect in the OH reaction of CH3Cl compared to CH4 reported by Gola et al. (Atmos. Chem. Phys. 2005, 5, 2395) can be explained by the lower barrier to internal rotation of the OH radical in the transition state of the CH4+OH reaction than in the CH3Cl+OH reaction. The deuterium kinetic isotope effects can be explained in terms of combined variational effects and tunneling.

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“…Like method II, this route especially benefits from the insolubility of the generated metal alkyl MR n , driving the reaction to completion. By using this method, Weiss and co-workers actually were able to synthesize and structurally characterize the methyl derivatives of Na, K, Rb, and Cs . On the other hand, well-defined calcium alkoxides are rather rare, and putative calcium tert -butoxide [Ca(O t Bu) 2 ] is seemingly unknown, which further complicated research in this field.…”

Section: Introductionmentioning

confidence: 99%

Dimethylcalcium

2018

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The salt metathesis reaction between homoleptic calcium bis(trimethylsilyl)amide [Ca{N(SiMe)}] and "halide-free" methyllithium allowed for the isolation of X-ray-amorphous dimethylcalcium [CaMe] in good yields and purities. The formation of [CaMe] was proven by microanalysis and NMR/FTIR spectroscopic methods as well as a series of derivatization reactions. Despite slowly decomposing thf, [CaMe] could be crystallized from chilled thf solutions as the heptametallic adduct [(thf)CaMe]. Reaction of [CaMe] with CaI in thf led to the dimeric complex [(thf)Ca(Me)(I)], whereas in tetrahydropyran (thp) the trinuclear complex [(thp)Ca(Me)(I)] was obtained, both representing the first crystallographically characterized heavy-Grignard compounds with methyl groups as the hydrocarbyl ligand. While protonolysis of [CaMe] with the superbulky proligand HTp in nonpolar solvents gave homoleptic (Tp)Ca, reaction in donor solvents (thf, thp) afforded the monomeric complexes [(Tp)Ca(Me)(thf)] and [(Tp)Ca(Me)(thp)], which are the first examples bearing terminal Ca-CH functionalities. Grignard-type nucleophilic methyl-group transfer to hexamethylacetone gave access to the dimeric alkoxide complexes [(thf)Ca(OCtBuMe)] and [(tBuCO)Ca(μ-OCtBuMe)Ca(OCtBuMe)]. Finally, addition of the Lewis acid GaMe to [CaMe] led to the corresponding tetramethylgallate compound [Ca(GaMe)].

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Über Metallalkyl- und -aryl-Verbindungen

Cited by 37 publications

References 23 publications

New supramolecular assemblies in heterobimetallic chemistry: synthesis of a homologous series of unsolvated alkali-metal zincates

New supramolecular assemblies in heterobimetallic chemistry: synthesis of a homologous series of unsolvated alkali-metal zincates

Study of the Carbon-13 and Deuterium Kinetic Isotope Effects in the Cl and OH Reactions of CH₄ and CH₃Cl

Dimethylcalcium

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Über Metallalkyl- und -aryl-Verbindungen

Cited by 37 publications

References 23 publications

New supramolecular assemblies in heterobimetallic chemistry: synthesis of a homologous series of unsolvated alkali-metal zincates

New supramolecular assemblies in heterobimetallic chemistry: synthesis of a homologous series of unsolvated alkali-metal zincates

Study of the Carbon-13 and Deuterium Kinetic Isotope Effects in the Cl and OH Reactions of CH4 and CH3Cl

Dimethylcalcium

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Study of the Carbon-13 and Deuterium Kinetic Isotope Effects in the Cl and OH Reactions of CH₄ and CH₃Cl