Hexakis(dimethylformamide)iron(II) complex cation in hexahalorhenate(IV)-based salts: synthesis, X-ray structure and magnetic properties.

Two iron(II)-rhenium(IV) compounds of general formula [FeII(dmf)6][ReIVX6] [X = Cl (<bold>1</bold>) and Br (<bold>2</bold>); dmf = <italic>N</italic>,<italic>N</italic>-dimethylformamide] have been prepared and characterized. X-ray powder diffraction measurements on samples of <bold>1</bold> and <bold>2</bold> support the same structure for both systems. The crystal structure of <bold>1</bold> was determined by single-crystal X-ray diffraction. <bold>1</bold> crystallizes in the triclinic system with space group <italic>P</italic>ī. Each iron(II) is six-coordinate and bonded to six oxygens from six dmf molecules building a distorted octahedral environment. Rhenium(IV) is six-coordinate by six halide anions in an almost regular octahedral geometry. The magnetic properties were investigated from variable-temperature magnetic susceptibility measurements performed on microcrystalline samples of <bold>1</bold> and <bold>2</bold>, whose experimental data were reproduced by a model of two isolated paramagnetic centers [<italic>S</italic> = 2 (FeII) and <italic>S</italic> = 3/2 (ReIV)] with large values of zero-field splitting (zfs) parameter. [ABSTRACT FROM AUTHOR]