On isoelectronic fluorides [H3tren]⋅(AlF6)⋅H2O, [H3tren]⋅(AlF6)⋅HF, [H4tren]⋅(AlF6)⋅(F) and the iron analogue [H4tren]⋅(FeF6)⋅(F)

[H3tren]⋅(AlF6)⋅H2O, [H3tren]⋅(AlF6)⋅HF and [H4tren]⋅(MF6)⋅(F) (M=AlM=Al, Fe), are obtained by hydrothermal technique and microwave heating in the (Al(OH)3,FeF3)-tren-(HF/H2O)-ethanol system. Structure determinations are performed from single crystal X-ray diffraction data. All phases are built up from (MF6)3− anions linked by hydrogen bonds to [H3tren]3+ or [H4tren]4+ cations and to water or HF molecules or “isolated” fluoride anions. [H3tren]3+ and [H4tren]4+ cations adopt a “spider” shape configuration.Surprisingly, the HF molecule is strongly hydrogen bonded with one fluoride ion of the AlF6 octahedron (dF⋯F=2.38 Å)(dF⋯F=2.38 Å) in [H3tren]⋅(AlF6)⋅HF while “isolated” fluoride ion is weakly coordinated by three hydrogen atoms in [H4tren]⋅(MF6)⋅(F).The evolution of the formulations, from [H3tren]⋅(AlF6)⋅H2O to [H3tren]⋅(AlF6)⋅HF and to [H4tren]⋅(MF6)⋅(F) (M=AlM=Al, Fe), is linked with the increase of the HF content of the starting solution. The volumes per formula unit decrease from 321.3(1) Å3 and 320.6(1) Å3 in [H3tren]⋅(AlF6)⋅H2O and [H3tren]⋅(AlF6)⋅HF, respectively, to 298.5(4) Å3 in [H4tren]⋅(AlF6)⋅(F).

Figure optionsDownload as PowerPoint slide