Straightforward One-Pot Syntheses of Silylamides of Magnesium and Calcium via an In Situ Grignard Metalation Method

Abstract

Calcium bis[bis(trimethylsilyl)amide] (Ca(HMDS)2) is a widely used reagent in diverse stoichiometric and catalytic applications. These processes necessitate a straightforward and large-scale access of this complex. Calcium does not react with primary and secondary amines, but the addition of excess bromoethane to a mixture of calcium turnings and amines in THF at room temperature yields the corresponding calcium bis(amides), calcium bromide and ethane. This in situ Grignard metalation method (iGMM) allows the preparation of calcium bis(amides) from secondary and primary trialkylsilyl-substituted amines and anilines on a multigram scale.1 Background2 The In Situ Grignard Metalation Method (iGMM)3 Properties of [(thf)2M(HMDS)2]4 Applications and Perspective

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

“…In order to circumvent these challenges, we developed the in situ Grignard metalation method (iGMM), a one‐pot synthesis for the preparation of Mg{N(SiMe 3 ) 2 } 2 . [24] In analogy to this procedure, Mg turnings and cyclopentadiene (HCp) were suspended in an ethereal solvent and bromoethane was added at 0 °C within 30 minutes. Then the reaction mixture was warmed to room temperature and decanted from excess of magnesium.…”

“…[23] In this study an improved straightforward synthesis of cyclopentadienyl magnesium bromides in ethereal solvents is presented by transferring the in situ Grignard metalation method (iGMM) to this compound class; so far this process has only been established for the synthesis of Mg{N(SiMe 3 ) 2 } 2 . [24] Furthermore, the elucidation of thermodynamic data of the temperature-dependent Schlenk equilibrium is reported.…”

Stripping and Plating a Magnesium Metal Anode in Bromide‐Based Non‐Nucleophilic Electrolytes

“…The synthesis proceeded smoothly and yielded Mg(HMDS)Br and ethane and can be scaled up to a multigram scale. Advantageously, ethane is liberated and analytically pure Mg(HMDS)Br can be isolated . In THF solution, several equilibria are operative.…”

“…However, the development of a halide‐free noncorrosive electrolyte still faces many challenges . As for Mg(HMDS)Cl, a straightforward preparation route was used to obtain an electrochemically viable Mg(HMDS)Br/THF electrolyte …”

Magnesiated and Calciated N‐Mesityl Diphenylphosphinic Amides

“…Deprotonation of N ‐mesityl‐ P,P ‐diphenylphosphinic amide (HL, 1 ) was achieved in THF at room temperature using the metalation reagents MgBu 2 and [(thf) 2 Ca{N(SiMe 3 ) 2 } 2 ] (commonly abbreviated as [(thf) 2 Ca{hmds} 2 ]), respectively, yielding the complexes [(thf) n M{Ph 2 P(=O)–N–Mes} 2 {Ph 2 P(=O)–NH‐Mes} 2 ] [M/ n = Mg/0 ( 2 ), Ca/2 ( 3 )] of the general type of [(thf) n M(L · HL) 2 ] (Scheme ; the anionic ligand L is shown in red). Recrystallization from solvent mixtures of THF and diethyl ether or pentane gave crystals that were suitable for X‐ray diffraction experiments.…”