Atomic magnetic susceptibilities, determination

The compound is formed due to Se loss when Nd pellets or sheets and Se powder in the ratio 2 3 are reacted at 1050°C and melted at 1700°C, see p. 133, Eisner et al. [1]. The lattice constant determined for cubic NdSe 33 was 8.864 A, as compared with a literature value of 8.659 A for Nd3Se4 [1]. A value a = 8.879 A for Nd3Se4 is reported by Yarembash [2]. This author gave the melting point as 1750°C and the atomic magnetic susceptibility at room temperature as 5800x10-6cm3/mol Nd. 

Response to external field is used to determine magnetic susceptibility and electronic ground state of spin system Nuclear magnetic resonance (NMR) sjjectra Observe some atoms from protein and solvent, report on protein and, indirectly, the iron center. 

Observe atoms not directly bonded to metal magnetization transferred at a distance Observe at normal biological temperatures Determine bulk magnetic susceptibility... 

The determination of n from measurement of peff is the most familiar application of magnetic susceptibility measurements to inorganic chemists. To the extent that the spin-only formula is valid, it is possible to obtain the oxidation state of the central atom in a complex. Thus an iron complex with a peff of 5.9B.M. certainly contains Fe(III) (high-spin d5) and not Fe(II). The diamagnetism of AgO rules out its formulation as silver(II) oxide, because Ag2+ has an odd number of electrons (d9) and should be paramagnetic it contains Ag(I) and Ag(III), in equal amounts. There are, however, a number of pitfalls, especially if reliance is placed on a single measurement at room temperature. The Curie law is rarely obeyed within the limits of experimental error. This means that the measured peff is somewhat temperature-dependent. A number of factors can be responsible for deviations from ideal Curie (or even Curie-Weiss) behaviour, and/or from the spin-only formula. 

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