Magnetic properties lower oxides

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... 

The lower oxide of iodine, lOg, can be made by treating an iodate with concentrated sulfuric acid and then adding water. This oxide is a yellow solid. The magnetic properties of the substance show that its formula is not I2O4 the substance is paramagnetic, which show s that it has an odd number of electrons in the molecule. 

Taken together, the work summarized here indicates that thioethers exhibit a marked preference for the lower, softer oxidation states. Put another way, they strongly stabilize lower oxidation and spin states of metal ions. They do so by accepting electron density from the metal back into a orbitals on the thioether that are of n symmetry with respect to the metal. This delocalization manifests itself not only in the redox properties of thioether complexes, but also in their magnetic and EPR behavior. 

The drawback of the use of iron NPs is their air sensitivity. In an effort to combine good magnetic properties with air stability, we considered iron carbides. Theses phases form readily when iron is in the presence of a carbon source at high temperature, or at lower temperature under the conditions of the Fischer-Tropsch syntheses, namely in the presence of CO and Hj at temperatures between 200 and 300 °C. Prior to our work no synthesis of monodisperse iron carbide NPs had been described. Addition of Fe(CO)5 to preformed monodisperse iron NPs leads, depending on the gas atmosphere to iron carbide or core-shell iron/iron carbide NPs [53], These particles were found to display excellent magnetic properties and to be stable in air after an initial period presumably corresponding to some surface oxidation. 

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