A convenient method for the synthesis of alkali metal pentafluoromanganates(III)

Abstract

Reaction of MnO(OH) and a concentrated solution of AHF₂ (A = NH₄⁺, Na⁺, K⁺ or Cs⁺) in 40% hydrofluoric acid gives instantaneously rose-pink coloured alkali metal pentafluoromanganate(III), A₂MnF₅ (A = NH₄⁺ or Na⁺), and alkali metal pentafluoromanganate(III) monohydrate, A₂MnF₅.H₂O (A = K⁺ or Cs⁺). Li₂MnF₅ has been synthesised by reacting lithium carbonate with a solution of MnO (OH) in 40% hydrofluoric acid followed by addition of a small amount of alcohol. Characterisation of the compounds and assignment of molecular structure were made from the elemental analyses, chemical determination of oxidation state of manganese in the compounds, magnetic susceptibility measurements and infra red spectral studies.