Magnetic properties also compounds

Apart from TiO and the lower halides already mentioned, the chemistry of these metals in oxidation states lower than 3 is not well established. Addition compounds of the type [TiCl2L2] can be formed with difficulty with ligands such as dimethylformamide and acetonitrile, but their magnetic properties suggest that they also are polymeric with appreciable metal-metal bonding. However, the electronic spectra of Ti in TiCl2/AlCl3 melts and also of Ti incorporated in NaCl crystals (prepared by... 

In particular, we have found unusual magnetic properties within a series of Eu-ln-P compounds that we have recently synthesized Eu3lnP3, Eu3ln2P4, and Euln2P2 [24—26]. The first two can be described as classical Zintl phases and the third shows semi-metaUic properties. EuIn2P2 may also be a Zintl phase with the semi-metaUic properties attributed to adventitious crossing of the valence band with the conduction band. 

After a consideration of optical transitions in which MMCT plays a role, and after a characterization of the excited states involved, a short review of mixed-valence compounds and their spectroscopy is in order. For more extended reviews we refer to Refs. [60,97], At least 40 elements of the periodic table form mixed-valence species which are of importance in solid state physics and chemistry, inorganic chemistry, materials science, geology and bioinorganic chemistry. It is usually their colors which are their most striking property (see also above), but they have more intriguing properties, for example electrical and magnetic properties. 

E(d 2) ligand field interpretations of the magnetic properties of sandwich compounds. 

The first attempts to rationalize the magnetic properties of rare earth compounds date back to Hund [10], who analysed the magnetic moment observed at room temperature in the framework of the old quantum theory, finding a remarkable agreement with predictions, except for Eu3+ and Sm3+ compounds. The inclusion by Laporte [11] of the contribution of excited multiplets for these ions did not provide the correct estimate of the magnetic properties at room temperature, and it was not until Van Vleck [12] introduced second-order effects that agreement could be obtained also for these two ions. 

The calculations also bring to light a significant U ( = ) interaction between the metal center and the C=C bond of the endo dithiolene ligand in the U(V) anionic complex, which does not exist in the dianionic species. Again, magnetic properties of these air-sensitive compounds were not investigated. 

Zelentsov et al. also observed that the high spin fraction in virtually all samples increased to varying extents after the samples were heated [105]. The origin of this effect is not clear since the complexes were mostly unsolvated and thus loss of solvate molecules, the most common cause of such a change, was not applicable. Nevertheless, the importance of the inclusion of lattice water molecules in co-determining the spin crossover properties is evident in the different magnetic properties of Li[Fe(5-Br-thsa)2] [105] and Li[Fe(5-Br-thsa)2]-H20 [111]. For the unsolvated compound neg= 1.93 B.M. 

Due to the number of isotype compounds, systematic studies of physical properties of divalent metals phosphonates are of interest. For instance, systematic studies of magnetic properties could be carried out by varying the paramagnetic metal center [8, 12]. The organic part may also be varied systematically in order to determine the origin of a cooperative effect yielding... 

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