Ruthenium-99: Mossbauer isotope

The catalysts were prepared by an incipient wetness impregnation technique, using aqueous solutions of RuCls and Fe(NOs)3. Solutions of predetermined concentrations were added dropwise to silica (HS-5 Cab-O-Sil from Cabot Corp.) with constant mixing. Sequential impregnations of ruthenium and then iron were used for the bimetallic catalysts, and all samples were dried overnight at 383 K after any impregnation step. The iron nitrate solution was 93% isotopically enriched in the Te Mossbauer isotope. 

Dr. Erickson For those interested in coordination chemistry, certain other transition metal atoms are suitable for Mossbauer spectroscopy. One in particular is ruthenium which is just below iron in the Periodic Table. It is a difficult isotope to work with since it requires helium temperatures almost exclusively. I don t know whether it is possible to work at nitrogen temperatures or not, but Kistner at Brookhaven has examined various ruthenium compounds from the 2-j- to the 8+ oxidation states with interesting results. These are not published yet, but at least his work offers the possibility of going down one element below the other in the Periodic Table to study chemical effects. Osmium, which is below ruthenium, can also be Mossbauered. Some sort of systematic study like this involving elements in the various transition series would be extremely interesting. 

There has been to some degree the belief that Mossbauer spectroscopy, although in principle an ideal technique for catalyst studies, for practical purposes can only be applied to problems in catalysis if the catalyst contains either iron or tin. Therefore, one of the main purposes of this review is to show how Mossbauer spectroscopy can be directly extended to many additional Mossbauer atoms or isotopes (such as antimony, europium, nickel, ruthenium, gold, and tungsten) and, perhaps more importantly, how the technique can be extended to obtain information about systems that do not contain a Mossbauer atom. ... 

Even though the Mossbauer effect has been observed for almost 50 different elements and ca. 100 different nuclides, only a few of these elements are widely used as Mossbauer effect probes. The nuclides which are both experimentally viable and yield useful chemical information are iron-57, tin-119, antimony-121, and europium-151. More difficult to use but of importance in coordination chemistry are gold-197, nickel-61, ruthenium-99, tellurium-125, iodine-129, dysprosium-161, tungsten-182, and neptunium-237. Among these isotopes, iron-57 is by far the easiest, most informative, and most widely used nuclide in both traditional coordination chemistry and in studies of biologically significant coordination complexes. 

However, although about 90 isotopes are Mossbauer active isotopes, only a few can be utilized for Mossbauer spectroscopic studies, and these are mostly restricted to iron compounds, tin compounds, ruthenium compounds, and antimony compounds. 

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