Synthesis, characterisation and modelling of a ferromagnetically coupled chromium(III) Dimer: Di-μ-hydroxobis[tetrakis(isothiocyanato)chromate(III)]
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A rare example of a ferromagnetically coupled dinuclear chromium(III) complex, the di-μ-hydroxobis[tetrakis(isothiocyanato)chromate(III)] anion, is reported. This complex has been synthesised from the oxo-bridged acetonitrile complex [(CH3CN)5CrOCr(NCCH3)5](BF4)4 and isolated as the solvated tetraphenylphosphonium salt, (Ph4P)4[(SCN)4Cr(OH)2Cr(NCS)4]·2CH3CN (1). From magnetometry the coupling constant, J, was determined to be -5.17 cm-1 (in an H = JSA·SB scheme). The X-band EPR spectra were measured in the temperature range 2-305 K and the data were modelled. The spectra, which are very rich, are the first reported for a ferromagnetically coupled Cr-diol, and they allow for detailed modelling that encompasses zero-field splittings (ZFS) and fourth-order spin-Hamiltonian parameters for the coupled system. The structural parameters that determine the magnitude and sign of the exchange coupling were studied with broken-symmetry DFT. These results are discussed in terms of and compared to existing angular overlap model (AOM)-based magneto-structural correlations. This furnishes qualitative as well as quantitative insight into the coupling mechanisms.
|Journal||European Journal of Inorganic Chemistry|
|Number of pages||7|
|Publication status||Published - 2014|
- Broken symmetry, Chromium, EPR spectroscopy, Magnetic properties, Thiocyanates