Evidence for a radical-forming process during the reaction of solid NH4SCN with n-butyl-lithium and hexamethylphosphosphoramide (HMPA) in toluene: crystal structure of the product, (LiNCS·2HMPA)2

Abstract

The complex (LiSCN·2HMPA)_n, (1)[HMPA = O:P(NMe₂)₃], was synthesised by the reaction of solid NH₄SCN with BuⁿLi and HMPA (1 : 1 : 2 molar ratios) in toluene and shown to have an asymmetrical dimeric structure (n= 2) comprising terminal (HMPA)₂Li– and (SCN)₂Li– units whose metal centres are then bridged by two µ₂-HMPA ligands; e.s.r. spectroscopic investigations on the reactions system (which proceeds through a series of colours) have detected the intermediacy of thiocyanate-based radical species.