Effect, paramagnetic

The above discussion ignores all paramagnetic effects including band paramagnetism. Evidence for a Curie-like contribution is seen at low temperatures in some of the curves displayed in Fig. 5 and could arise, in part, from paramagnetic impurities (see below). 

The present status of the field effects may be summarized as follows both the high nuclear charge and paramagnetic effects seem to be well-established for spectroscopic transitions,449 463 but neither of them has been demonstrated unambiguously for radical reaction rates. 

The drastic paramagnetic effect on transverse relaxation rates can be used to make the distinction between binding and nonbinding compounds so clear that analysis of SLAPS-... 

Fig. 23. Schematic representation of the mechanism describing the paramagnetic effect in Gd(III)-doped zeolite suspensions.

A similar approach could be used to explain the mechanism of the paramagnetic effect caused by other, insoluble particles with encapsulated paramagnetic ions. 

Fung, C. H., Mildvan, A. S., Allerhand, A, Komoroski, R., and Scrutton, M. C. (1973). Interaction of pyruvate with pyruvate carboxylase and pyruvate kinase as studied by paramagnetic effects on relaxation rates. Biochemistry 12, 620-629. 

Then, curium metal is antiferromagnetic and its paramagnetic effective moment definitively supports the picture of a localized 5 f configuration the same is true for what is known about berkelium and californium metals ... 

The EPR spectral data indicated that two cyanide anions bind to copper at low temperature where two cyanide anions and two histidines are present in the basal plane and the third histidine residue is present in the axial position. It has been proposed that the second cyanide anion displaces the coordinated water. Similarly, it has been proposed that the oxalate anion coordinated in a bidentate fashion and displaced the coordinated water. In case of sulfonamides, the coordination geometry is reported to be the same as that of ZnCa. 13C NMR spectroscopy was used to explore the location of C02 and HCO3 with respect to metal ion in CuCa (129,130,138). It indicated that HCO3 is bound directly to Cu (137). The affinity constant of C02 for CuCa is <1 M-1 but the paramagnetic effect is paradoxically high (130). These results indicated that C02 does not bind to a specific site but probably is attracted by the cavity either by hydrophobic interactions or by the metal ion or by both. 

The carbide atom in 1 is located in the center of the square face such that it is partially exposed whereas the carbide atom in 2 is completely encapsulated by the six ruthenium atoms. From a spectroscopic viewpoint, carbide atoms are very distinctive and the earlier reviews have dealt with these aspects in detail.7 8 The IR spectrum of 1 contains peaks at 701 (s) and 670(m) cm 1, and 2 contains peaks at 717(sh), 703(s), 680(m), and 669(m) cm-1.22 I3C-NMR spectra of 1 and 2 do not appear to have been reported. This is probably due to the low yields in which these compounds were initially obtained at a time when, 3C-NMR was still not in widespread use in cluster chemistry. In general, the 13C-NMR resonance of carbide atoms ranges from 8 250 to 500. The high frequency resonances exhibited in 13C-NMR spectra reflect the different diamagnetic and paramagnetic effects experienced by a nucleus in such an unusual chemical environment.23... 

When 1 is added to a solution of a mixture of enantiomers, A and A, it associates differently with each of the two components to produce the diastereo-meric complexes A+ 1 and A 1. The nmr spectrum of the mixture then shows shift differences that are large compared to the uncomplexed enantiomers (because of the paramagnetic effect of the europium) and normally the resonances of the A+ 1 complex will be distinct from those of the A 1 complex. An example of the behavior to be expected is shown in the proton nmr spectrum (Figure 19-4) of the enantiomers of 1-phenylethanamine in the presence of 1. Although not all of the resonances are separated equally, the resolution is good for the resonances of nuclei closest to the metal atom and permits an estimate of the ratio of enantiomers as about 2 1 and the enantiomeric purity as 33%. 

Paramagnetic effects on the l/7 and /T2 relaxation rates of 13C and 31P nuclei of adenylylated glutamine synthetase ([2-13C]AMP-GS) were measured when the two enzyme-bound Mg2+ ions were replaced by Mn2+ (121). Also the paramagnetic effects of Co2 + were measured on the 3 P relaxation rates of adenylylated enzyme. Distances between these metal ions and the l3C and 31P nuclei are summarized in Fig. 26. 

In the very fast exchange regions, the observed paramagnetic effects on the chemical shift Aa)p and the relaxation rates / ip, R2p, are simply proportional to the full paramagnetic effects in the metal binding site, as summarized below ... 

Therefore, if the molar fraction of bound ligand /m is known, the full paramagnetic effects can be calculated. Of course, if no exchange takes place, the ligand in the bulk solution is completely insensitive to the presence of the paramagnetic metal ion. 

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