Electronic configuration crossover

Figure 6.8 The Sugano-Tanabe diagram of a 3d electronic configuration (C/5 = 4.5). The two vertical lines correspond to the DqlB values in the crossover and for the ruby crystal (see the text). The inset shows the energy-level diagram for strong crystal fields.

We now return finally to take up the point with which we ended the first paragraph in section 2.1 viz. via what means is doping that bears delocalized d-electrons successful in promoting configuration crossover in a solid like SmS or TmTe Earlier we illustrated, by citing that CaS (ag = 5.68 A) doping of SmS (ag = 5.96 A) leaves the... 

Since the MO approach is a theoretical model, what experimental evidence is there for this tr-Tr crossover The actual electronic configurations of molecules are nearly always determined spectroscopically, particularly by... 

The detailed electronic configuration of a transition-metal ion (e.g. 5 = I, i, or i for a ion), orbital populations, and mixed ligand-field crossover complexes can be studied in detail. Electronic spin relaxation is known in paramagnetic ions. The pressure dependence may give additional information on the bonding-type and anisotropy of the crystal. 

In Chapters 6 and 7 the data for both high-spin and low-spin iron(II) and iron(III) complexes were discussed. Although these are the common electronic configurations for these oxidation states, there is also a minority group of compounds which show either ligand field crossover from high-spin to low-spin configuration or intermediate spin states, and in addition there are some uncommon oxidation states. 

V-methylpyridyl species (Scheme 1.10). This unusual effect, which did not appear in the corresponding reactions of the Mn(IV) and Mn(III) states, was ascribed to the low spin, d electronic configuration of oxoMn(V). Thus, a spin-state crossover is required during reduction with the promotion of an electron from d to d. ... 

The spin crossover phenomenon is known to take place in cubic coordination systems of transition metal compounds (TMC) with electronic configurations that may produce either HS or LS complexes, subject to the strength of the ligand field [24, 25]. For some values of the latter the two electronic configurations, HS... 

Since the MO approach is a theoretical model, what experimental evidence is there for this a-n crossover The actual electronic configurations of molecules are nearly always determined spectroscopically, particularly by photoelectron spectroscopy, a technique in which electrons in different orbitals are distinguished by their ionization energies (see Box 5.1). Experimental data support the orbital orderings shown in Figure 2.9. Table 2.1... 

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