Complex halides magnetic properties

Many complexes contain the [Cr2X9]3 ion.1073-1076 This unit consists of two distorted octahedra which share a face there are three bridging and three terminal halides (226). The distortion of the octahedron is such that the two metal ions are displaced from each other. The magnetic properties of these complexes have been the subject of extensive study summarized in Table 93. 

Made by fusion, they possess the six-coordinate elpasolite structure in which the perfectly octahedral [LnCle] " ions occupy sites with cubic symmetry. These have been much studied for their optical and magnetic properties on account of this, the Ln + ions on their highly symmetrical sites having especially weak f-f transitions in their electronic spectra. Some other A2BMX6 systems also adopt the elpasolite structure. Other halide complexes like (Ph3PH)3(LnX6) and (pyH)3(LnX6) (X = Cl, Br, I) have been made by solution methods ... 

Experimental measurements of the optical absorption spectra and magnetic properties of transition-metal complexes provide a critical test of the validity of crystal field theory. The theory makes specific predictions about the strengths of crystal fields produced by different ligands. Charged ligands such as the halides... 

Contents R.D.Shannon, H.Vincent Relationships between Covalency, Interatomic Distances, and Magnetic Properties in Halides and Chalcogenides. -A.Kjekshus, T.Rakke Considerations on the Valence Concept. - A.Kjekshus, T.Rakke Geometrical Considerations on the Marcasite Type Structure. -G.C.Allen, K.D.Warren The Electronic Spectra of the Hexafluoro Complexes of the Second and Third Transition Series. 

The oxidation of the iron(III) complexes [Fe(DAS)2X2][FeX4] (DAS = o-phenylenebis-dimethylarsine, X = Cl, Br) with concentrated nitric acid followed by addition of the appropriate anion led to the isolation of black [Fe(DAS)2X2]Y2 (Y = BF, CIO, ReO ). The magnetic properties indicate two unpaired electrons consistent with a low-spin configuration in a tetragonal trans halide) structure. Mossbauer quadrupole splittings are large ( 3.2mms ) and temperature independent. ... 

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