Synthesis, structure of [H 3dien]·( MF 6)·H 2O ( M=Cr, Fe) and 57Fe Mössbauer study of [H 3dien]·(FeF 6)·H 2O

Abstract

Single crystals of [H 3 dien]·(FeF 6)·H 2O ( I) and [H 3 dien]·(CrF 6)·H 2O ( II) are obtained by solvothermal synthesis under microwave heating. I is orthorhombic ( Pna2 1) with a=11.530(2) Å, b=6.6446(8) Å, c=13.787(3) Å, V=1056.3(2) Å 3 and Z=4. II is monoclinic ( P2 1 /c) with a=13.706(1) Å, b=6.7606(6) Å, c=11.3181(9) Å, β=99.38(1)°, V=1034.7(1) Å 3 and Z=4. The structure determinations, performed from single crystal X-ray diffraction data, lead to the R 1/w R 2 reliability factors 0.028/0.066 for I and 0.035/0.102 for II. The structures of I and II are built up from isolated FeF 6 or CrF 6 octahedra, water molecules and triprotonated amines. In both structures, each octahedron is connected by hydrogen bonds to six organic cations and two water molecules. The iron-based compound is also characterized by 57Fe Mössbauer spectrometry: the hyperfine structure confirms the presence of Fe 3+ in octahedral coordination and reveals the existence of paramagnetic spin fluctuations.