Die Kettenstruktur der hydratisierten Tetramethylammoniummangan(II)-hexacyanometallate(III) NMe₄MnFe(CN)₆ · 8 H₂O und NMe₄Mn₂(CN)₆ · 8 H₂O / The Chain Structure of the Hydrated Tetramethylammoniummanganese(II)-hexacyanom etallates(III) NMe₄MnFe(CN)₆ · 8 H₂O und NMe₄Mn₂(CN)₆ · 8 H₂O

Abstract

The crystal structures of the isomorphic tetragonalcompounds NMe 4 MnFe(CN) 6 ·8 H 2 O (a = 1067.0, c = 1056.8 pm ) and NMe 4 Mn 2 (CN) 6 · 8 H 2 O (a = 1066.9, c = 1064.1 pm ), space group P4/n, Z = 2 , were determined (R = 0 .03). The structure is built up from slightly distorted M(CN) 6 3− octahedra and square planar Mn(H 2 O) 4 2+ cations, stacked one upon the other in nearly eclipsed positions to form cyanobridged chains - Mn -NC -Mm -CN -along [001]. The average distances in the compounds are: Fe -C = 193.8 (Mn -C -199.3) pm, C -N = 114.7 (114.7 ) pm , Mn -N = 220 .2 (218 .2) pm, Mn -O = 218 .8 (218 .5) pm. The differences of bridge lengths are discussed, as well as the orientation and contact distances of the tetramethylammonium cations. These and additional crystal water, forming H -bonded(H 2 O) 4 rings, occupy positions in the center of elpasolite- like sub cells, which result from O -H ··· N bridging between different chains. Some further relations to the structures of elpasolite and prussian blue are pointed out.