Paramagnetic iron

Recently, Lipton et al. [25] have used zinc-67 NMR to investigate [Zn(HB(3,5-(CH3)2pz)3)2] complexes which have been doped with traces of paramagnetic [Fe(HB(3,4,5-(CH3)3pz)3)2]. The low-temperature Boltzmann enhanced cross polarization between XH and 67Zn has shown that the paramagnetic iron(II) dopant reduces the proton spin-lattice relaxation time, Tj, of the zinc complexes without changing the proton spin-lattice relaxation time in the Tip rotating time frame. This approach and the resulting structural information has proven very useful in the study of various four-coordinate and six-coordinate zinc(II) poly(pyrazolyl)borate complexes that are useful as enzymatic models. 

In Situ Mossbauer Measurement on Hematite/Divalent Co-57. The adsorption behavior of cobaltous ions on hematite surfaces was essentially the same as that on silica reported by James and Healy (12). Appreciable adsorption begins at about pH 4 followed by an abrupt increase in adsorption between pH 6 and 8. Beyond pH 9, adsorption is practically complete. Emission Mossbauer spectra of Fe-57 arising from the divalent Co-57 ions at the interface between hematite particles and the 0.1 mol/dm3 NaCl solutions of different pH at room temperature are shown in Figure 3 The emission spectra show a marked dependence on the pH of the aqueous phase. No emission lines ascribable to paramagnetic iron species are recognized in... 

In in vitro experiments, MSC developed an early myogenic phenotype (Jaquet et al, 2005), however we did not succeed in generating self-contracting or even twitching (cardio-) myoc54es (not shown). Our results reveal that MSC are able to survive at least 10 weeks within the rat myocardium. When paramagnetic iron oxide nanoparticles were incorporated into rMSC prior to transplantation, cells within the myocardial scar area could be detected in our study. This could be some evidence that rMSC are able to migrate into the scar from the site of injection. 

Jaccarino, V., and if. G. Shulman Nuclear magnetic resonance in paramagnetic iron group fluorides. Phys. Rev. 106, 602 (1957). 

The tetrathiomolybdate anion [MoS4]2 acts as a chelating ligand toward iron in both diiron complexes [Fe2(SR)2(NO)4] and tetrairon complexes [Fe4S3(NO)7] and [Fe4S4(NO)4] to yield two paramagnetic iron-nitrosyls which have been assigned (55) the constitutions 15 and 16 ... 

FeAl204 reduction to metallic iron. The background of the fully reduced catalyst indicated the absence of FeAl204 or any other paramagnetic iron phase. 

NEXAFS methods can be applied to nearly all elements, is not restricted to certain isotopes, does not typically exhibit interferences (e.g., paramagnetic iron with nuclear magnetic resonance (NMR) spectroscopy), and does not necessarily require sample drying (Williams et al., 1993 Kirz et al., 1995). An additional advantage is the ability of NEXAFS to directly interrogate the composition of minor or... 

The pseudocontact shifts arise from the dipolar interaction between the magnetic moment of the unpaired electrons in the paramagnetic iron atoms and the resonating protons. The general form for the magnitude of the pseudocontact shifts in transition metal complexes can be given as follows ... 

Mossbauer spectroscopy has matured into one of the classical techniques for catalyst characterization, although its application is limited to a relatively small number of elements which exhibit the Mossbauer effect. The technique is used to identify phases, determine oxidation states, and to follow the kinetics of bulk reactions. Mossbauer spectra of super-paramagnetic iron particles in applied magnetic fields can be used to determine particle sizes. In favorable cases, the technique also provides information on the structure of catalysts. The great advantage of Mossbauer spectroscopy is that its high-energy photons can visualize the insides of reactors in order to reveal information on catalysts under in-situ conditions. 

S = 3/2 systems. Whilst this has the disadvantage that EPR yields little information about the nature of the FeIV present, it has the advantage that a lot of information is potentially obtainable from the protein-bound S = 1/2 free radical. However, despite the fact that EPR is ideally suited to study the nature of free radicals, there are some problems due to the presence of a nearby paramagnetic iron centre. 

Fe(dppe)2H]a Square Very few paramagnetic iron(I) complexes have been 3... 

The Spin Hamiltonian Formalism Determination of Zero-Field Splitting D and Rhombicity E/D of Paramagnetic Iron Centers by Mossbauer Spectroscopy... 

It shonld be noted here that a correct determination of fine and hyperfine stmctnre parameters should be done in snch a way that spectra taken under different experimental conditions (variable external fields and/or variable temperatnres) are reprodnced with the same parameter set. This reprodnction of the experimental data is often a bit less accnrate than when one fits only a single experimental spectmm. However, owing to the many parameters involved in the simnlation it makes absolntely no sense to deduce a complete spin Hamiltonian parameter set of a paramagnetic iron center from jnst one Mossbaner spectmm. 

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