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Synthesis, Characterisation and Modelling of a Ferromagnetically Coupled Chromium(III) Dimer: Di‐μ‐hydroxobis[tetrakis(isothiocyanato)chromate(III)]
Author(s) -
Morsing Thorbjørn J.,
Weihe Høgni,
Bendix Jesper
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201402779
Subject(s) - chemistry , chromate conversion coating , electron paramagnetic resonance , chromium , dimer , coupling constant , acetonitrile , crystallography , inorganic chemistry , computational chemistry , nuclear magnetic resonance , physics , organic chemistry , particle physics , chromatography
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 [(CH 3 CN) 5 CrOCr(NCCH 3 ) 5 ](BF 4 ) 4 and isolated as the solvated tetraphenylphosphonium salt, (Ph 4 P) 4 [(SCN) 4 Cr(OH) 2 Cr(NCS) 4 ] · 2CH 3 CN ( 1 ). From magnetometry the coupling constant, J , was determined to be –5.17 cm –1 (in an H = J S A · S B 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.