Synthesis and Structure Determination of Bicyclic [Li(tmeda)]₂[S₆]

Abstract

An Li2S6 system of the bicycle[4.1.1] type is the distinctive feature of the title compound 1. The corresponding “nucleus” is depicted in the illustration to the right, in which the two tetramethylenediamine ligands are not fully drawn. No such structures have so far been observed for other alkali metal, alkaline earth, or transition metal polysulfides.

Lithium polysulfide conformer analysis in ether-based solvents for Li–S batteries

“…3a), the lithium cation lies in the centre of the hexasulfide dianion (very near to the PS centre of mass; see the S 6 -Li radial distribution function in Fig. S3 †) with Li-S distances of 2.3-2.8 Å, which are comparable with the X-ray crystallographic data of 2.49 Å in Li(TMEDA) 2 S 6 crystals 1,42 and N,N,N′,N′-tetramethylethylenediamine (TMEDA). By tracing the minimum Li-S distance for each conformer (2.32 Å, see the distribution curve in Fig.…”

The role of polysulfide dianions and radical anions in the chemical, physical and biological sciences, including sulfur-based batteries

“…6). 41 Due to the small size of the naked Li cation and its high electric field strength, the Li-S interactions can be considered as partly covalent and partly ionic. Consequently, the Raman spectrum contains not only typical SS stretching modes in the region 390-500 cm À1 , but also Li-S stretching modes (near and below 390 cm À1 ) which most probably are coupled to the SS stretching fundamentals of the neighbouring bonds.…”

Accessing the CpArNi(I) Synthon: Reactions with N-Heterocyclic Carbenes, TEMPO, Sulfur, and Selenium

“…There are several examples where an S 6 2– anion terminally connects two metal atoms, including silver, ruthenium, , bismuth, and nickel complexes . However, bicyclic M 2 S 6 rings (M = any metal) were observed only for alkali metal sulfides − such as [Li­(tmeda)] 2 S 6 (tmeda = N,N,N ′ ,N ′-tetramethyl­ethylenediamine) and a tellurium complex [(Ph 3 Te) 2 S 6 ] . The seven-membered NiS 6 rings in 5 adopt “crown-like” conformations, while the Ni 2 S 2 core is bent, having a fold angle of 25.55(8)°.…”