Rhodium magnetic susceptibility

It is a matter of speculation as to whether or not the activity would pass through a significant maximum at a surface composition between 0 and 30% Rh. It is interesting to note in this connection that the magnetic susceptibility (156, 157) and the electronic specific heat coefficient (156) increase from low values at 60% Ag-Pd through pure palladium and reach a maximum at - 5% Rh-Pd, thereafter decreasing smoothly to pure rhodium. Activity maxima have also been reported for reduced mixed oxides and supported alloys of group VIII metal pairs. For example, in the... 

The reaction of mam-porphyrin IX diethyl ester with [Ir(Cl)(CO)3]2 or [Ir(Cl)(CO)(cot)2] yields the iridium(III) porphyrin derivative [Ir(CO)(HePDEE)] (HePDEE = hematoporphyrin diethyl ester).457 This complex, along with the dimethyl ester derivative, has been characterized by electronic, IR, electron spin resonance and mass spectroscopic techniques as well as magnetic susceptibility measurements. The iridium complexes differ from their rhodium analogues in that they retain a CO ligand in the coordination shell. 

Table I. Magnetic susceptibility—temperature data for rhodium pentafluoride...

The Faraday microbalance used here has been described elsewhere [7], Details about the procedure we have followed to determine the magnetic susceptibility of the Rh/Ce02 catalysts are reported in refs. [3,8], The experimental values, which were corrected from the traces of ferromagnetic impurities (6-12 ppm), allowed us to determine the content of paramagnetic Ce3+ ions, and therefore the percentage of Ce4+ ions reduced to the 3+ oxidation state [8], The magnetic contribution of rhodium was considered to be negligeable (Maximum value to be expected 3.10" emu CGS at 298 K, to be multiplied by 12.56 to obtain SI units in m. g-l). 

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]). 

Pig. 143. RuOj. Magnetic susceptibility, normalized to the value at T=0K, is plotted versus T Data for rhodium are included for comparison [70R19]. 

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