Paramagnetic component

The shielding tensor, and its diamagnetic and paramagnetic components, are not necessarily symmetric in the Cartesian indices [25-29], and the shielding tensor can in general be decomposed into a symmetric and an antisymmetric component, i.e. 

Figure 2 Correlation diagram for H NMR spectra of Cp Fe(Et2C2B3H3)CoCp in CDCI3 (for the oxidation) and THF-ds (for the reductions), showing <5 plotted vs. mole fraction of the paramagnetic component (g.70 Reproduced with permission of the American Chemical Society.

With the quadrupole doublet assigned to the [2Fe]H cluster, the two remaining paramagnetic components have to be arising from the [4Fe-4S]H cluster. Detailed analysis of the magnetic components recorded under various magnetic field supports this assignment. The parameters obtained from the analysis are AEq = 1.12 0.05 mm/s, 8 = 0.49 0.03 mm/s, q = 1.4,... 

To understand the sample (material) magnetism, one needs to comprehend the nature of molecular magnetism. The two paramagnetic components of the salt can take part in electron exchanges (EE). One type of electron exchange is D+ <— A and the other is D+ — A . These types of electron interactions are depicted in EE graphs from 1 to 5 in Scheme 8.14. 

Fig. 43. Iron phases observed during the reaction of C2H2 with Fe2Oj at 1270 K. (I)Fc,, 0, (2) a-Fe, (3) Fe3C, (4) paramagnetic component. Figure according to Maksimov et al. (249).

The paramagnetic component of the shielding tensor along the molecular axis is zero thus al can be accurately calculated by ab initio methods. Flygare (22) has shown that, to a good approximation ... 

The dependence of NMR chemical shifts on the molar ratio of complex components may be used for studies of the stoichiometry of the complex (252,256,258,263) (Fig. 1). The resonance of some nuclei of the electron donors changes considerably on complexation with silanes. Particularly large changes are observed for the 15N resonance ( 100 ppm upfield) since the paramagnetic component of the 15N-NMR chemical shift is eliminated on quarternization of nitrogen. Mixing of equimolar amounts of pyridine and triphenylsilyl perchlorate was demonstrated to lead to a shift of the 15N-NMR signal from 314.0 to 216.8 ppm, which was taken as evidence for the formation of a 1 1 ionic complex (18). 

Multinuclear NMR spectroscopy makes it possible to obtain data on electron density distribution in clathrochelate molecules and their structure. The resonance on the ° Co nucleus provides information on the spatial and electronic structure of the coordination polyhedron of an encapsulated cobalt(III) ions. A dominant contribution to the chemical shift is made by the paramagnetic component Bo, which is linearly determinated by d-d transition energy =... 

This is due to a decrease in the electron-accepting properties of halogenide substitutents and, hence, leads to an increase in the s-electron density on the tin atom nucleus (a similar effect was observed for tin(IV) tetrahalides). The " Sn NMR chemical shift values increase in the halogen series Br < F < Cl (Table 24), which is different from the previous order. Similar results were discussed above for cobalt(III) compounds and were explained by a predominance of the paramagnetic component in the i Sn NMR chemical shift. 

Some of those have long been known a is the electric dipole polarizability (a symmetric polar tensor of dimension P) in length formalism, k (an asymmetric axial tensor of dimension P t) is related to the optical activity, A is the mixed dipole-quadrupole polarizability, x is the magnetic susceptibility (or magnetizability), written as a sum of diamagnetic and paramagnetic components. 

Some calculated contributions to the paramagnetic component of the nitrogen screening... 

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