Magnetic susceptibilities electron distribution

The application of a static electric field polarizes the electronic charge distribution and leads to changes in molecular magnetic susceptibility and nuclear... 

In the case of Fe(OEC)Py susceptibility measurements indicated a S = 3/2 ground state for the metal atom (p = 3.80 BM) but this characterization is not in agreement with Mossbauer data (8Fe = — 0.09 mms 1, AEq = 3.88 mms"1) which correspond rather to those observed for the Fe4+ complexes. The hypothesis has been considered that the complex would be an Fe4+ corrole anion radical the magnetic properties (S = 3/2) of which would result from ferromagnetic spin coupling of Fe4+ (S = 1) with a macrocycle anion radical (S = 1/2) [27]. Theoretical studies are necessary to completely characterize the electron distribution in the complex. 

The large difference in chemical shift observed for corresponding resonances in the spectra of Fe(OEC)Cl and Fe(OEC)Ph are indicative of a different electronic distribution in the two species. The two complexes have very similar magnetic susceptibilities (p = 2.97 BM and 2.89 BM, respectively). 

It is doubtful that a distinction can be made between the various charge distributions proposed by purely chemical means, although this might be possible in principle. We thus rely on physical methods such as optical studies, x-ray analysis, polarography, magnetic susceptibility, and electron paramagnetic resonance (EPR) studies for a determination of the stmcture of these complex cations. This is not to say that the chemistry of these compounds is no longer of... 

Photoelectron spectroscopy and measurements of the specific heat and magnetic susceptibility are methods available to gain information about the DOS. In disordered systems, the former gives electron-distribution curves (EDC) reflecting the band density of states [5.61]. Whereas the UPS-method reveals the shape of the DOS and hardly gives the absolute value of the density of states, specific heat as well as susceptibility measurements, on the other hand, give only N(EF). 

Now, if the elements in the total magnetic susceptibility tensor can also be measured, the numerical value of xj can be extracted, xj depends only on the ground electronic state electron distribution and gives some notion of the outer electronic shape of the molecule. 

Another check is provided by the diamagnetic susceptibility Xm, of the molecules in the vapour state (Banyard i960). This is the sum of a paramagnetic term Xnt oe to the magnetic moment associated with excited states, which can be calculated from spectroscopic data, and a purely diamagnetic term Xr which is related to the electron distribution in the ground state by... 

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