Infrared spectra of and of indicate weak to moderate NÈHAE AE AEN (N 2 H 5 ) 2 HGaF 6 AE 2H 2 O ( N 2 H 5 ) 2 HFeF 6 AE 2H 2 O hydrogen bonding. Data are interpreted in terms of a double minimum symmetrical potential well with a high barrier and statistical distribution of hydrogen in the minima on both sides of the barrier, forming an hydrogen-bonded cluster with simultaneous presence of and ions. H 3 N'H 2 NAE AE AEH'NH 2 NH 3 ' N 2 H 5 ' N 2 H 6 2' The strong Raman NN stretching band, which is characteristic of the type of cation, is split into two bands when cooled to 77 K and merged again when warmed to room temperature. This indicates that H-bridged ions N 2 H 5 ' are spectroscopically indistinguishable at room temperature, presumably because of a high rate of phonon-assisted proton tunnelling through the barrier. This process is inhibited at lower temperature, thus making the and N 2 H 5 ' ions distinguishable. is only weakly hydrogen bonded, not protonated and therefore fairly easily N 2 H 6 2' H 2 O released. Octahedral symmetry of and of ions is demonstrated. Single-crystal x-ray structure deter-GaF
6 3-FeF 6 3minations on the Fe compound at three di †erent temperatures (296, 200 and 90 K) corroborate the spectroscopic results ; in particular, the statistical distribution of one H-atom within the cation was revealed. No structural phase transition was observed down to 90 K. The compound crystallizes in space group C2/c (No. 15) with a = 1444.28(13) pm, b = 640.09(6) pm, c = 1048.09(9) pm, b = 118.942(6)Ä and Z = 4 at 90 K. The octahedron around Fe is slightly compressed with FeÈF distances along the pseudo-fourfold axis at 193.07 pm shorter than those within the plane (193.86 pm on average). The magnetic moment of the Fe(III) complex was determined as 5.