Magnetic susceptibility, determination

Experimental structure elucidation techniques can be used to characterize radicals if conditions can be found in which the radicals are produced in higher concentration and with longer lifetimes than is the case under typical reaction conditions. For example, the relative stability of the triphenylmethyl radical (4) allows it to be studied by magnetic susceptibility determination. 

The magnetic susceptibility determined for the series of compounds tri-, tetra-, and pentaphenylchromium iodide was found to be approximately... 

Gouy balance A balance for the determination of magnetic susceptibility. The sample is weighed in and out of a magnetic field and the susceptibility is calculated from the difference in weights. 

Electrobalances suitable for thermogravimetry are readily adapted for measurements of magnetic susceptibility [333—336] by the Faraday method, with or without variable temperature [337] and data processing facilities [338]. This approach has been particularly valuable in determinations of the changes in oxidation states which occur during the decompositions of iron, cobalt and chromium oxides and hydroxides [339] and during the formation of ferrites [340]. The method requires higher concentrations of ions than those needed in Mossbauer spectroscopy, but the apparatus, techniques and interpretation of observations are often simpler. 

The multiplicity can be determined from the experimental values of the magnetic susceptibility, the magnetic moment in Bohr magnetons being equal to 2 VS(S + l), in which S is the spin quantum number. (The multiplicity is 2S + 1.) The moments for 22 and 62 are 1.73 and 5.91, respectively. The experimental values for K3Fe(CN)6 and (NH jFeF are 2.0 and 5.88, respectively, so that the bonds in the [FefCN ] ion are electron-pair bonds, and those in [FeFe]a are ionic. 

The limited magnetic measurements of very mixed -metal clusters are summarized in Table XIII. The magnetic behavior of some anti-ferromagnetic very mixed -metal carbonyl clusters (Fig. 82) has been studied by Pasynskii and eo-workers. Temperature dependences of the magnetic susceptibilities of Cr2Co(/t3-S)3(/i-SBu )(CO)2() -C3H4R)2l (R = H. Me) have been determined us-... 

Magnetic Susceptibility. Magnetization as a function of applied field was determined at various temperatures according to the Faraday method. A Cahn model RG microbalance and an Alpha model 4800 magnet were used In this respect. A detailed description of the technique used can be found in reference 4. 

Size of sample 2 was determined using magnetic susceptibility, as described below. 

Following the completion of the sintering study, a study was conducted to demonstrate that 663 K, the temperature at which all magnetic susceptibility measurements were taken, was indeed greater than Tq, . As discussed in the theory section, measurements were made at several temperatures until it was determined that plots of M/Mg versus H/T collapsed onto a single curve. It is clear from Figure 4 that Tqj, must be less than 450 K. That is, for any temperature above 450 K the average particle size was measured to be nearly 200 A in diameter. For smaller particles, Tq, will of course be an even lower temperature. This proves that all measurements made at 663 K were indeed accurate. 

Spin-state transitions have been studied by the application of numerous physical techniques such as the measurement of magnetic susceptibility, optical and vibrational spectroscopy, the Fe-Mbssbauer effect, EPR, NMR, and EXAFS spectroscopy, the measurement of heat capacity, and others. Most of these studies have been adequately reviewed. The somewhat older surveys [3, 19] cover the complete field of spin-state transitions. Several more recent review articles [20, 21, 22, 23, 24, 25] have been devoted exclusively to spin-state transitions in compounds of iron(II). Two reviews [26, 27] have considered inter alia the available theoretical models of spin-state transitions. Of particular interest is the determination of the X-ray crystal structures of spin transition compounds at two or more temperatures thus approaching the structures of the pure HS and LS electronic isomers. A recent survey [6] concentrates particularly on these studies. 

It is thus evident that, in order to interpret the results obtained by one of the relaxation methods, a thorough investigation of the unperturbed equilibrium properties is required. In general, solution magnetic susceptibilities measured by the NMR method of Evans [83, 84] are used to this end, the equilibrium constant for the equilibrium in Eq. (37) being determined by ... 

The reports about the crystal structure of Mn(Et2cftc)2, determined by means of X-ray powder diagrams are contradictory. According to Fackler and Holah (18) this compound is isomorphous with Cu(Et2rftc)2, but Lahiry and Anand (44) state the complex to be isostructural with Ni(Et2 tc)2- EPR data (g = 1.92 and g = 4.11) and magnetic susceptibility measurements (4.1 BM at room temperature) show the compound to be the first Mn(II) complex with a quartet ground state (44). 

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