57Fe-NMR

Schreckenbach, G., 1999, The 57Fe NMR Shielding in Ferrocene Revisited. A Density-Functional Study of Orbital Energies, Shielding Mechanisms, and the Influence of the Exchange-Correlation Functional , J. Chem. Phys., 110, 11936. 

Figure 10. Graph showing the correlation between experimental 57Fe NMR chemical shifts (points at top left are organometallics,from Biihl, Ref. 20, at bottom right, they are for metalloporphyrins, see Ref 19) and theoretical G94/B3LYP results. The solid circles represent shieldings computed directly from protein crystal structures containing tilted/bent Fe-C-0 subunits, and are inconsistent with experiment. See Refs. 19,23 for more details.

Mink, L.M., Christensen, KA. and Walker, F.A. (1992) Rapid detection of 57Fe NMR chemical shifts of model hemes an approximate correlation between 57Fe and 31P chemical shifts of Fe(II) porphyrins bound to phosphine axial ligands./. Am. Chem. Soc., 114, 6930-6931. 

Reaction of FeCo2(CO)9S with a series of phosphines (31, 133) and isocyanides (126) yielded mono-, di-, and trisubstituted derivatives, Eqs. (77) and (78). 57Fe-Mossbauer spectra of the phosphine-substituted derivatives indicated that substitution at cobalt occurs prior to substitution at iron (31). Unfortunately, no crystallographic evidence has been obtained for any of these derivatives, and the precise stereochemistry has not been resolved, even with the aid of l3C-NMR spectra (9). The problem is compounded with the isocyanide ligands since several isomers of the trisubstituted derivatives are formed. 

AgFe2 M-CHCPh(NHMe) ( -PPh2)(C0)6][CI04] IR, H, 31P NMR, 57Fe Mossbauer Yes Trigonal planar AgFe2 unit 189... 

NMR spectra of nuclei such as 57Fe (spin V2) in magnetic materials can be measured without external magnetic field. Also in the case of nuclear quadrupole resonance (NQR) no static magnetic field is necessary. For this reason NQR is sometimes called "zero field NMR". It is used to detect atoms whose nuclei have a nuclear quadrupole moment, such as 14N and 35C1. 

Mossbauer spectroscopy is of special significance for species containing paramagnetic 57Fe nuclei, which render the NMR technique not as useful. This technique could also be utilized for homo- and heterometallic alkoxides of Mossbauer active nuclei such as ll9Sn and mSb. 

Fig. 1. 62.8 MHz 2°7Pb NMR spectrum of (Cp)Fe(CO)2-PbMe3 (25 °C =5% in C6D6), recorded by using the refocused INEPT pulse sequence with CPD H decoupling (200 transients with a repetition time of 8 s and an acquisition time of 4 s).94 The line width h, /2 = 2 Hz is rather small for 207Pb NMR signals and makes it possible to observe 57Fe satellites and also 13C satellites in order to measure accurately the isotope-induced chemical shifts...

Besnus et al. (1982) have performed magnetization, diffuse neutron scattering, 57Fe Mossbauer and NMR studies on these C15 Laves phase compounds over a wide range of composition. The Curie temperatures and average moments are reduced with increasing Mn content and it was concluded from the neutron and NMR data... 

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