Reactions of (−)-sparteine with alkali metal HMDS complexes: conventional meets the unconventional

Abstract

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Mixed Lithium Amide–Lithium Halide Compounds: Unusual Halide‐Deficient Amido Metal Anionic Crowns

“…In all cases, 7 Li spectra revealed two different lithium environments, in keeping with the solid state structures, and the expected donor amine to HMDS ratio in the respective 1 H NMR spectra was observed. An interesting feature was observed in the 1 H NMR spectrum of 4.…”

“…[7] Given that this diamine-NaHMDS system has formally captured monomeric NaOH, we envisaged that a similar LiHMDS system could capture substoichiometric quantities of other salts, and particularly the Lewis amphoteric metal halides, which appear far more important than metal hydroxides for metal salt-enhanced reactions.…”

“…1 H, 13 C, and 7 Li NMR spectroscopic studies were conducted on C 6 D 6 solutions of 2-5. In all cases, 7 Li spectra revealed two different lithium environments, in keeping with the solid state structures, and the expected donor amine to HMDS ratio in the respective 1 H NMR spectra was observed.…”

Controlled synthesis of lanthanide–lithium inverse crown ether complexes

“…In recent years, the synthesis and characterization of inverse crown ether complexes (II, Chart 1) have received considerable attention because of their interesting structural feature and wide applications in homogeneous catalysis [1][2][3][4][5][6]. In most cases, inverse crown ether complexes are heterobimetallic complexes (M1 ≠ M2) or special ate complexes.…”

Synthesis and structure of cationic guanidinate-bridged bimetallic {Li7M} cubes (M = Mn, Co, Zn) with inverse crown counter anions

“…24 The majority of inverse crowns are heterobimetallic combinations of an alkali metal with a less polar divalent metal, so it is notable that the inverse crown in 3 is a cyclic pentamer of [Li(hmds)]. 25 The solid-state structure of lithium hexamethyldisilazide is the cyclic trimer [Li(hmds)] 3 , however in hydrocarbon solution a tetramer-dimer equilibrium has been observed. 26 To account for the formation of 3, an aggregation process involving [Li(hmds)] n units with n = 1, 2, 3 or 4 templating around the nascent chloride ion can be envisaged, although proof for this cannot be obtained by NMR spectroscopy owing to the paramagnetism of [2][3] and [4] [3].…”