Ionic complexes, mass spectra

No precautions to exclude air are necessary as the product is completely stable in air. The mass spectrum of the product showed that no complexed phosphine oxides are present. The tricarbonyl hydride produced by this simple procedure is the starting material for the preparation of the ionic tetracarbonyl salt described below in the next procedure as well as for preparation of the covalent tosylate obtained by treatment of the hydride with p-toluenesulfonic acid. 

Several non-volatile ionic complexes of As and Sb have been characterized by fast atom bombardment mass spectrometry (Table 12). The mass spectrum of 53 (a mixture of 3-nitrobenzyl alcohol with CH2CI2 was used as the matrix) exhibits (M -I- BF2), M, (M - 2CO)- -, CpFe(CO)2 +, Cp2Fe+ and Bi-" ions ... 

The mass spectrum reflects sufficiently precisely the identity of the molecule. The relative numbers of each of the kinds of ionic fragments are characteristic for every compound so that the mass spectrum becomes a sort of fingerprint for each compound. Differences in these various molecular fingerprints are noticeable enough to allow identification of the individual constituents of even a complex mixture. 

Figure 8 Infrared spectrum of the mass-selected H2-HCO " ionic complex recorded with the apparatus shown in Figure 7.

Another example of chemical class screening using MS/MS is demonstrated in Figure 5. Again, the simplicity of the APCI/MS/MS neutral loss spectrum of rose oil is evident by comparison to the relative complexity of the APCI/MS spectrum of the same sample shown above it. In this MS/MS neutral loss spectrum we are looking at all those ionic species present which lose neutral water (H2O 18 mass units). This would include the oxygenated... 

With this method, we have shown [27] that the two main bands of the excitation spectrum recorded at naphthol-(NH3)2+ mass peak do not belong to the same species one band excitation leads to a narrow mass peak and thus corresponds to the direct excitation of 1 -2 complex, since the other one leads to a broad peak and corresponds to the excitation of the 1 -3 complex, which looses one ammonia molecule in the ionic state. 

The need for a cationization reagent in MALDI analysis of polymers can also create some complications in mass spectral interpretation [42, 56]. For example, the spectrum in Figure 8.3b shows a secondary distribution of lower intensity in addition to the principal distribution. This secondary distribution could be due to cation adduction with different ionic species and/or the presence of other polymeric species with different end-group structures. In this case, the secondary distribution has oligomer mass shifts of -1-22.4 Da from the nearest oligomer of lower mass in the principal distribution. This is consistent with the generation of salt cluster complexes, similar to what has been observed in the ESI of polystyrene [57]. For polyisoprene, it takes the form of [polyisoprene-i-Cu(copper retinoate)]L This amounts to an actual mass shift of -1-363.0 Da with respect to the principal distribution of [polyisoprene-tCujL This is consistent with the observed mass shift of 22.4 Da plus six repeat units of 64.2 Da. 

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