Synthesis of isotopic forms of dilithiomethane [(CH26Li2)n and (CD2Li2)n] and preliminary structural information obtained by x-ray powder and solid-phase carbon-13 NMR techniques

Abstract

New synthetic methods have been developed to alter the Ziegler procedure' for synthesis of dilithiomethane of various isotopic compositions. [CH2(6Li2)], has been prepared to facilitate solid I3C NMR spectra. (CD2Li2), has been prepared, and preliminary X-ray powder pattern data are reported. The first solid-state 13C NMR spectrum on any organolithium compound has been obtained. The I3C NMR spectra of solid samples of [CH3(6Li)]4 and [CH2(6Liz)], are discussed. Bis( (trifluoromethy1)sulfonyl) imide, (CF3S02)2NH, the parent compound of the bis((perfluoroalky1)sulfonyl) imides, has been prepared in good yield. The strong electron-withdrawing effect of the (CF3S02)2N group is borne out by the acidity of the imide and the properties of its derivatives. The synthesis and properties of (CF3S02)2NH are described, as well as those of the derivatives (CF3SOJ2NX, where X = Cs, CI, NO, NO2, and Si(CH&.

Homo‐ and Heterodimetallic Geminal Dianions Derived from the Bis(phosphinimine) {Ph2P(NSiMe3)}2CH2 and the Alkali Metals Li, Na, and K

“…[9] Subsequent advances in synthetic methods [10,11] A C H T U N G T R E N N U N G allowed the structural characterization of Li 2 CD 2 by Stucky in 1990, using a combination of neutron and X-ray diffrac-…”

Chiral Dilithiomethane Derivatives: Structure Determination and Application in Stereoselective Reactions

“…A structural study by Gais and co-workers provided evidence for a solvent-separated contact ion pair of 10c, which is devoid of Li-C contacts. [22] The monomeric species 10c consists of a [Li (12-crown-4) 2 ] cation and a sulfonimidoylsubstituted allylic anion. The conformation of the lone pair in 10c suggests a stabilising n C -s* S-Ph interaction (negative hyperconjugation) reminiscent of lithiosulfones.…”

“…A significant reduction in the S-C(α) bond length from 1.783(2) Å in the starting material to 1.66(1) Å in 10e is observed ( Figure 3). The dinuclear lithium complex 10f of a lithiated vinylic sulfoximine is bridged through Li-sulfoximine-O bonds, forming two eight-membered rings with the different atomic sequences (Li-O-S-N) 2 and (Li-O-S-C) 2 , respectively. [27] The two halves of the molecule are related by a crystallographic centre of symmetry ( Figure 4).…”

“…Since its discovery, dilithiomethane (2) has challenged researchers in various fields of chemistry such as synthetic organic chemistry, organometallic chemistry, and computational chemistry. The first landmark was achieved by Ziegler et al who developed the first synthetic route to dilithiomethane.…”

“…After early solid state NMR studies, Stucky et al suggested an X-ray structure of CD 2 Li 2 in 1990 derived from powder diffraction data. [2,3] Computational studies suggested various gas phase structures and even higher aggregates of 2. [4] For synthetic purposes, however, heteroatom-substituted organolithiums are better qualified than simple alkyllithium compounds.…”