Isotope organometallic compounds

The isotope patterns for two simple organometallic compounds in the molecular ion region (a) dimethylmercury and (b) dimethylplatinum. The seven isotopes of mercury show clearly and appear quite different from the six isotopes of platinum. Since there are only two carbon atoms, the contribution from C is negligible. 

The only respect in which the hot atom chemistry of organometallic compounds has so far been applied to other fields of study is in the area of isotope enrichment. Much of this has been done for isolation of radioactive nuclides from other radioactive species for the purpose of nuclear chemical study, or for the preparation of high specific activity radioactive tracers. Some examples of these applications have been given in Table II. The most serious difficulty with preparation of carrier-free tracers by this method is that of radiolysis of the target compound, which can be severe under conditions suited to commercial isotope production, so that the radiolysis products dilute the enriched isotopes. A balance can be struck in some cases, however, between high yield and high specific activity (19, 7J),... 

Isotope Abundances Negative Ions Synthetic Models V. High-Resolution Studies VI. Metastable-Ion Techniques VII. Coupled Gas Chromatography and Mass Spectrometry Inorganic and Organometallic Compounds VIII. Conclusion. ... 

Mass spectroscopic studies of organometallic compounds are almost as old as the field of mass spectrometry nickel tetracarbonyl was studied by J. J. Thomson (/) and Aston (2,3) in their work on the isotope ratios of nickel. Following this early flurry of specialized interest, however, inorganic and organometallic mass spectral studies were... 

C. Radiochemical Syntheses and Uses of Organometallic Compounds of Radioactive Bismuth Isotopes... 

By reaction of nickel acetylacetonate with organometallic compounds in ether in the presence of all-fran -cyclodecatriene, we obtained an intensely red solution from which dark red crystals could be isolated. These are volatile under high vacuum and have the composition NiCi2Hi8- The mass spectrum shows the molecule to have peaks at 220 and 222. This is in agreement with NiCi2Hi8, if we consider that nickel consists of the isotopes Ni and Ni . The infrared spectrum shows that all double bonds are shared with nickel, because there is no absorption corresponding to normal trans double bonds. 

For organometallic compounds, the situation becomes even more complicated because the presence of elements such as platinum, iron, and copper introduces more complex isotopic patterns. In a very general sense, for inorganic chemistry, as atomic number increases, the number of isotopes occurring naturally for any one element can increase considerably. An element of small atomic number, lithium, has only two natural isotopes, but tin has ten, xenon has nine, and mercury has seven isotopes. This general phenomenon should be approached with caution because, for example, yttrium of atomic mass 89 is monoisotopic, and iridium has just two natural isotopes at masses 191 and 193. Nevertheless, the occurrence and variation in patterns of multi-isotopic elements often make their mass spectrometric identification easy, as depicted for the cases of dimethylmercury and dimethylplatinum in Figure 47.4. 

Examples of primary methods used in determining multi-isotope trace elements are isotope dilution-based techniques (e.g. isotope dilution mass spectrometry), enabling traceability of the results to SI units. For organometallic compounds, the use of these techniques will hence guarantee traceability to SI units for the compounds in the extracts. 

In the analysis of mass spectra of organometallic compounds, advantage can often be taken of the characteristic isotope patterns of many metals. For example, the clusters in Figure 6-20 are similar to the isotope pattern of Mo2, which is distinctively different from the pattern for Mo, as illustrated in Figure 6-21. 

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