Characteristics magnetic properties

The characteristic magnetic properties of a particular radical may be so greatly modified by various possible modes of restricted rotation that, unless this is appreciated, the spectrum may be assigned to a new radical. The results for the fluorine center in BeO comprise an interesting variation on this theme. 

The nuclei of many isotopes possess an angular momentum, called spin, whose magnitude is described by the spin quantum number / (also called the nuclear spin). This quantity, which is characteristic of the nucleus, may have integral or halfvalues thus / = 0, 5, 1, f,. . . The isotopes C and 0 both have / = 0 hence, they have no magnetic properties. H, C, F, and P are important nuclei having / = 5, whereas and N have / = 1. 

EPR spectra of the native D. africanus Fdlll show an almost isotropic signal centered around g = 2.01 similar to the one observed in proteins containing [3Fe-4S] clusters (72). The temperature dependence of this signal and low-temperature MCD spectra and magnetization properties are identical to the ones reported for D. gigas Fdll (93). Upon one-electron reduction ag = 12 signal develops, characteristic of the [3Fe-4S] state. Two-electron reduction elicits an EPR active species with an axial properties and g-values of 1.93 and 2.05, consistent with the presence of a [4Fe-4S] center. 

In this section the salts based on metallocenium cations and metal bisdichalcogenate anions will be reviewed according to the previously referred structural classification. After referring to the general characteristics of the crystal structures the supramolec-ular features will be correlated with the magnetic properties. 

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