Structural characterization of potassium salts of the decamethylmanganocene anion Cp*2Mn−

Abstract

For the first time the crystal structure of a permethylated metallocene anion has been obtained. The 17 valence electron complex decamethylmanganocene Cp*₂Mn is reduced by molten potassium in THF to its extremely air-sensitive anion [Cp*₂Mn]⁻. The potassium salt [K(THF)₂]⁺[Cp*₂Mn]⁻ crystallizes upon cooling from hot THF and forms infinite polymeric chains exhibiting strong K⋯C contacts. In the presence of 18-crown-6 the polymeric structure is broken up. Crystals of [K(18-crown-6)(THF)₂]⁺[Cp*₂Mn]⁻ were obtained upon slow cooling from THF to −80 °C displaying well separated cations and anions.