Unusual routes to complexes of binary alkali metal–non-metal compounds: preparations and crystal and solution structures of Li2S6·(tmeda)2(tmeda = etramethylethylenediamine), and synthetic extensions of the routes

Abstract

The complex Li₂S₆·(tmeda)₂(tmeda = tetramethylethylenediamine) was obtained by reactions of BuⁿLi solution or Li metal or LiH solid with S powder suspended in toluene containing tmeda, or by tmeda/toluene extraction of the product from reaction of LiBH₄ and S (1 : 3 molar ratio) in tetrahydrofuran (thf): its crystal structure contains a central Li₂S₂ ring and there are alternating types of bond in the S₆ ^2– residue; in donor solvents, this dianion cleaves to give the bright blue S₃[graphic omitted] radical anion; several other complexes of type (MX_y·xL)_n have been prepared from reactions of alkali metals (M = Li, Na, K) with non-metals (X = S, Se, Te, P, As) in toluene containing stoicheiometric amounts of donors [L = hexamethylphosphoramide (hmpa), tmeda, pentamethyldiethylenetriamine (pmdeta)].