One‐Step Synthesis and Schlenk‐Type Equilibrium of Cyclopentadienylmagnesium Bromides

Abstract In the in situ Grignard metalation method (iGMM), the addition of bromoethane to a suspension of magnesium turnings and cyclopentadienes [C 5 H 6 (HCp), C 5 H 5 ‐Si( i Pr) 3 (HCp TIPS )] in diethyl ether smoothly yields heteroleptic [(Et 2 O)Mg(Cp R )(μ‐Br)] 2 (Cp R =Cp ( 1 ), Cp TIPS ( 2 )). The Schlenk equilibrium of 2 in toluene leads to ligand exchange and formation of homoleptic [Mg(Cp R ) 2 ] ( 3 ) and [(Et 2 O)MgBr(μ‐Br)] 2 ( 4 ). Interfering solvation and aggregation as well as ligand redistribution equilibria hamper a quantitative elucidation of thermodynamic data for the Schlenk equilibrium of 2 in toluene. In ethereal solvents, mononuclear species [(Et 2 O) 2 Mg(Cp TIPS )Br] ( 2’ ), [(Et 2 O) n Mg(Cp TIPS ) 2 ] ( 3’ ), and [(Et 2 O) 2 MgBr 2 ] ( 4’ ) coexist. Larger coordination numbers can be realized with cyclic ethers like tetrahydropyran allowing crystallization of [(thp) 4 MgBr 2 ] ( 5 ). The interpretation of the temperature‐dependency of the Schlenk equilibrium constant in diethyl ether gives a reaction enthalpy ΔH and reaction entropy ΔS of −11.5 kJ mol −1 and 60 J mol −1 , respectively.Cyclopentadienylmagnesium bromides are accessible with high yields by a fast and smooth one‐pot synthesis. In hydrocarbons and in ethereal solvents a dissociative Schlenk equilibrium is operative interconverting heteroleptic compounds into homoleptic congeners. imag

In Situ Grignard Metalation Method for the Synthesis of Hauser Bases

The in situ Grignard Metalation Method ( i GMM) is a straightforward one‐pot procedure to quickly produce multigram amounts of Hauser bases R 2 N‐MgBr which are valuable and vastly used metalation reagents and novel electrolytes for magnesium batteries. During addition of bromoethane to a suspension of Mg metal and secondary amine at room temperature in an ethereal solvent, a smooth reaction yields R 2 N‐MgBr under evolution of ethane within a few hours. A Schlenk equilibrium is operative, interconverting the Hauser bases into their solvated homoleptic congeners Mg(NR 2 ) 2 and MgBr 2 depending on the solvent. Scope and preconditions are studied, and side reactions limiting the yield have been investigated. DOSY NMR experiments and X‐ray crystal structures of characteristic examples clarify aggregation in solution and the solid state

In situ Grignard Metalation Method, Part II: Scope of the One‐Pot Synthesis of Organocalcium Compounds

The in situ Grignard Metalation Method ( i GMM) is a straightforward one‐pot strategy to synthesize alkaline‐earth metal amides in multi‐gram scale with high yields via addition of bromoethane to an ethereal suspension of a primary or secondary amine and magnesium (Part I) or calcium (Part II). This method is highly advantageous because no activation of calcium is required prior to the reaction. Contrary to the magnesium‐based i GMM, there are some limitations, the most conspicuous one is the large influence of steric factors. The preparation of Ca(hmds) 2 succeeds smoothly within a few hours with excellent yields opening the opportunity to prepare large amounts of this reagent. Side reactions and transfer of the i GMM to substituted anilines and N‐heterocycles as well as other H‐acidic substrates such as cyclopentadienes are studied. Bulky amidines cannot be converted directly to calcium amidinates via the i GMM but stoichiometric calciation with Ca(hmds) 2 enables their preparation

Suitability of Carbazolyl Hauser and Turbo‐Hauser Bases as Magnesium‐Based Electrolytes

Lithium-ion batteries pose certain drawbacks and alternatives are highly demanded. Requirements such as low corrosiveness, electrochemical stability and suitable electrolytes can be met by magnesium-ion batteries. Metalation of carbazole with Mg in THF in the presence of ethyl bromide yields the sparingly soluble Hauser base [(thf)$_{3}$Mg(Carb)Br] (1) which shows a Schlenk-type equilibrium with formation of [(thf)$_{3}$Mg(Carb)$_{2}$] and [(thf)4MgBr2]. A THF solution of 1 shows a low over-potential and a good cyclability of electrodeposition/-stripping of Mg on a Cu current collector. An improved performance is achieved with the turbo-Hauser bases [(thf)(Carb)Mg(μ-Br/X)$_{2}$Li(thf)$_{2}$] (X=Br (2) and Cl (3)) which show a significantly higher solubility in ethereal solvents. The THF solvation energies increase from (thf)$_{x}$MgBr$_{2}$ over (thf)$_{x}$Mg(Carb)Br to (thf)$_{x}$Mg(Carb)$_{2}$ for an equal number x of ligated THF molecules

Bericht zum Workshop »Korpus Kommunikation Kultur. Linguistik als Kulturwissenschaft« veranstaltet von der Research Area 5 "Culture, Language and the new Media" des International Graduate Centre for the Study of Culture (GCSC) Justus-Liebig-Universität Gießen, 4.11.2011.

Schüler L, Müller K, Saage S. Bericht zum Workshop »Korpus Kommunikation Kultur. Linguistik als Kulturwissenschaft« veranstaltet von der Research Area 5 "Culture, Language and the new Media" des International Graduate Centre for the Study of Culture (GCSC) Justus-Liebig-Universität Gießen, 4.11.2011. Vol 30/2012. KULT_online; 2012

Giessen Contributions to the Study of Culture, Bd. 11

Schüler L, Müller K, Benitt N, Koch C, Saage S. Linguistik als Kulturwissenschaft? Überlegungen zum Zusammenhang von Sprache, Wissen und Kultur. In: Benitt N, Koch C, Müller K, Saage S, Schüler L, eds. Kommunikation - Korpus - Kultur. Ansätze und Konzepte einer kulturwissenschaftlichen Linguistik. Trier: Wissenschaftlicher Verlag Trier; 2014: 1-24

Kommunikation – Korpus – Kultur: Ansätze und Konzepte einer kulturwissenschaftlichen Linguistik

Benitt N, Koch C, Müller K, Saage S, Schüler L, eds. Kommunikation – Korpus – Kultur: Ansätze und Konzepte einer kulturwissenschaftlichen Linguistik. Wissenschaftlicher Verlag Trier; 2014