Magnetic susceptibility measurement

2 Electronic Structures of Metal Clusters and Cluster Compounds 

the temperature independent negative diamagnetic susceptibility, and the second term accounts for the Curie-Weiss law which dominates at low temperatures, typically 100 K. The values found for the Curie-Weiss temperature 9 are generally rather low, 10 K. The effective magnetic moments deduced from the Curie constant, Co, are very small (0.1-0.5 per cluster) for clusters compo- 

Ihble 2-5. Distribution of unpaired electrons in free and carbonylated Ni clusters as derived from local spin density calculations [266, 267]. 

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Co(II), Ni(n), Cu(n), and Zn(II) complexes of Schiff bases derived from 4-aryl-2-aminothiazoles and salicylaldehyde have been prepared, and structure 276 (Scheme 170) was established by magnetic susceptibility measurements and by infrared, electronic, and mass spectra (512). 

However, magnetic-susceptibility measurements on other graphite-metal chlorides indicated that electron transfer is insufficient to account for reduction of the cation... 

Magnetic-susceptibility measurements showed the presence of UF4 in heated samples. Ebert et al. (E14) reported a nominal stoichiometry CisUFg, magnetic-susceptibility measurements indicating partial reduction at room temperature, with 10% of the uranium species present as U(IV). Wide-line NMR demonstrated the presence of both U(VI) and U(IV). 

The system Y(Rh xRUx)4B4(LuRu4B4 type, x > 0.15, x-ray diffraction, electron spcctropy, ac-magnetic susceptibility measurements) is similar. The abrupt disap-... 

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. 

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 ... 

J-mph denoting the four-dentate NjOj Jager-type ligand 4-methyl-l,2-phenylenebis(diacetylacetaldimine) [163]. Based on magnetic susceptibility measurements between 80 and 320 K, the transition is centred at 7[ — 212 K and is incomplete at both high and low temperatures. In order to reproduce the Mossbauer spectra between 84 and 319 K, three models of increasing sophistication were employed [164] ... 

Fe(6-Mepy)2(py)tren] (004)2 Doped in PSS. Magnetic susceptibilities measured for a microcrystalline sample of the complex produce a magnetic moment value = 0.36 pg at 10 K and 0.61 pg at 150 K, followed by a gradual increase to Peff = 2.80 pe at 311 K [138]. Thus 26% of the complexes are in the HS state at 300 K if a magnetic moment of 5.1 Pe is assumed for the pure HS compound. On the other hand, the complex doped into a polystyrene sulfonate (PSS) film does not provide any evidence for a thermal population of the HS state up to 340 K as demonstrated by variable-temperature UV-VIS and Mossbauer spectra. In fact, all the complexes doped into the PSS film are in the LS state at temperatures below 340 K. However, if irradiated by a single pulse of a Q-switched Nd/YAG laser (532 mp), the complex is excited from the LS ground state to the HS J2 states via an intermediate MLCT state and the metal states. The subsequent back relaxation from the excited T2 state to the... 

A careful magnetic and optical study of AgMn04 has been made by Sperka and Fritzer [45]. They find the Ag(I)-Mn(VII) MMCT transition at about 10000 cm (see Fig. 6). The ground state Ag(I)Mn(VII)04 is confirmed by magnetic susceptibility measurements. 

The W(IV) compounds W(Et2C c)4 (14) and [(CU.2)ndtc] (15) are characterised only by analytical data and magnetic susceptibility measurements. They are considered to be paramagnetic with moments of about 1.0 BM, which is in contrast with the diamagnetism of W(R2[Pg.94]

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). 

In this study, we extend the range of inorganic materials produced from polymeric precursors to include copper composites. Soluble complexes between poly(2-vinylpyridine) (P2VPy) and cupric chloride were prepared in a mixed solvent of 95% methanol 5% water. Pyrolysis of the isolated complexes results in the formation of carbonaceous composites of copper. The decomposition mechanism of the complexes was studied by optical, infrared, x-ray photoelectron and pyrolysis mass spectroscopy as well as thermogravimetric analysis and magnetic susceptibility measurements. 

The esr data of Prins and Reinders 144) were also used by Sohn, Hendrickson, and Gray 146) in a preliminary interpretation of their magnetic susceptibility measurements 99). Thus the g values reported were found to lead to the prediction of a substantial temperature dependence of the moment over the range studied, which was not in fact observed however, the data could be accommodated by assuming either that the distortion parameter, A, increased from about 300 to around 700 cm-1 between 4.2 K and 300 K, or that the 22+(ct 54) state lay only some 350 cm-1 above the ground level. 

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