Atomic spectra, transition metal

Similar experiments on a large number of transition metal carbonyls have shown that this process favors dissociation to and detection of metal clusters or atoms. Since most metal-(CO)n photofragments are themselves subject to efficient dissociation, MPI experiments do not identify the primary photoproducts. This situation contrasts sharply with electron impact ionization where the parent ion is usually formed and daughter ions are seen as a result of parent ion fragmentation. Figure 4 shows the electron impact mass spectrum of Mn2(C0) Q (33). for comparison with the MPI mass spectrum of Figure 3. 

There are two principal modes of coordination of the carbon monoxide ligand in transition metal carbonyls terminal coordination, to a single metal atom, and bridging coordination, to two or more metal atoms. The Ols spectrum of Co4(CO)12, shown in Fig. 5, can be readily deconvoluted into two peaks corresponding to these two types of carbonyl groups109. This spectrum is useful for determining the relative chemical shifts for the two types because... 

Analysis of the valence-band spectrum of NiO helped to understand the electronic structure of transition-metal compounds. It is to be noted that th.e crystal-field theory cannot explain the features over the entire valence-band region of NiO. It therefore becomes necessary to explicitly take into account the ligand(02p)-metal (Ni3d) hybridization and the intra-atomic Coulomb interaction, 11, in order to satisfactorily explain the spectral features. This has been done by approximating bulk NiO by a cluster (NiOg) ". The ground-state wave function Tg of this cluster is given by,... 

There is accordingly no conflict between the information about the states of the neutral iron atom, as shown by the iron spectrum, and our assumption that the metallic valence of iron has the value 6. In the same way we can see that large values of the metallic valence cau be accepted for other transition metals (such as 5.56 for copper), even though the electron, configuration for the lowest Btate of the isolated atom corresponds formally to a smaller valence (3dw4 for copper, corresponding to univalence). 

The products isolated from reactions of amides with transition metal halides usually contain coordinated halide (e.g. the formulations in Table 2). In some cases such as [Co(NMF)6][CoCLt], halide and amide are coordinated to different metal atoms, but when such compounds are dissolved in the neat ligand, halide can be replaced and at high dilution all the metal ions may be fully coordinated by the amide alone. The electronic spectrum resulting when this cobalt complex is dissolved in nitromethane has been interpreted as relating solely to the tetrahedral complex [CoC12(NMF)2]. 

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