Neue Mangan(III)-Fluoridhydrate: Na[MnF₄(H₂O)₂] und Na[MnF₄(H₂O)₂] · H₂O / New Fluoride Hydrates of Manganese(III): Na[MnF₄(H₂O)₂] and Na[MnF₄(H₂O)2] · H₂O

Abstract

Crystalline Na[MnF 4 (H 2 O) 2 ] and Na[MnF 4 (H 2 O)2] · H 2 O have been precipitated from aqueous HF solution of MnO(OH) and NaF. The crystal structure determination of the trihydrate (space group C 2/c, Z = 8, α = 1638.1(2), b = 667.6(2), c = 1130.3(1) pm, β = 103.78(1)°; R/wR = 0.038/0.033 for 1696 independent reflections) showed the presence of isolated octahedral trans-[MnF 4 (H 2 O) 2 ] - anions with an elongation of the H 2 O-Mn—OH 2 axis due to the Jahn-Teller effect (Mn 1-O 224.6(2), Mn 1—F(mean) 183.7(1); Mn2-0 218.3(2), Mn2— F(mean) 184.7(2) pm). As a consequence, an unusual H-bond geometry is observed with a tetrahedral (instead of trigonal) environment of the coordinated O atoms. Na[MnF 4 (H 2 O)2] is monoclinic (space group C 2/m, C 2 or Cm, a = 816.6(4), b = 677.1(1), c = 496.8(2), β = 114.45(3)°), the crystals show twinning and 1-dimensional disorder.