Osmium magnetic susceptibility

At room temperature, osmium hexafluoride yields a blue material of approximate composition CgOsFg (B22). Its magnetic susceptibility obeys the Curie-Weiss law, with a magnetic moment, /lefi = 3.5 BM,... 

For Os(PMe2Ph)2 P(OR)2Ph Cl3 (R = Me, Et) see p. 572. Reaction of osmium metal with PC15 at 600 °C gives a brown, volatile solid OsCl3-PCl3, the magnetic susceptibility of which was measured from 77 to 373 K at the latter temperature ptS is 1.94 BM.438 Presumably this material has a polymeric structure so as to give it octahedral coordination. 

It was assumed that OsO,F, would be colourless and diamagnetic and phjrsically similar to OsOF, and OsF,. The infrared spectra of osmium oxide pentafluoride samples taken from a variety of preparations were identical with one another. The entire product from one oxyfluorination of osmium metal was subjected to infrared examination. The bulk of the sample in a Monel trap, was isolated from the gas cell by a Hoke valve. After each vapour sample had been scanned it was discarded and a new sample of vapour admitted. This was repeated exhaustively. All the spectra were interpretable in terms of OsF OsOF OsO and traces of HF, CF, SiF and CO,. Two independent magnetic measurements on samples of OsOF one from an oxjrfluorination of the metal and the other from the fluorination of the dioxide gave magnetic susceptibility values equal within the usual experimental uncertainty. Furthermore the magnitude of the susceptibility was consistent with pure OsOF,. 

Johnson et al. reported a systematic investigation of magnetism in the cluster carbonyls of osmium. The experimental quantity of most direct interest was the excess molecular susceptibility (Xems) of the Os cluster compounds, which is the difference between the experimentally determined magnetic susceptibility of the molecular complex (Fig. 8) and the sum of the diamagnetic corrections of those species from which the high-nuclearity cluster is composed. 

All platinum metals are paramagnetic (x > 0). The magnetic susceptibilities of palladium and platinum decrease with increasing temperature, the magnetic susceptibilities of rhodium, iridium, ruthenium, and osmium increase with increasing temperature (Fig. 3.1-272 [1.218]). 

Magnetic susceptibilities of osmium clusters show the evolution of "metallic" behaviour for high nuclearity species. Electrochemical measurements have been made on several cluster systems, including... 

Figure 9. Magnetism in osmium cluster carbonyls. The variation of the high-temperature (298 K) excess molecular susceptibility, as a function of cluster nuclearity. Taken from Johnson et...

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