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57Fe NMR spectroscopy has limited application on iron chemistry basically due to its very low sensitivity.NMR REFERENCES
A typical external standard sample is Fe(CO)5. Its absolute frequency is 3.237778 MHz with respect to 100.00 MHz for TMS. Also see IUPAC recommendations for reporting the NMR chemical shits of all nuclei relative to the 1H resonance of TMS (02JMR323-156).NMR PARAMETERS
Some interesting features of the Fe nucleus are:NMR EXPERIMENTS
- 57Fe chemical shifts cover a range of 9000 ppm including diene Fe(0) complexes (-600ppm/+1700ppm), cyclopentadienyl iron compounds (+1000/+5100ppm), and myoglobin derivatives (+7200/+8200ppm).
- 1J(57Fe,1H) and 1J(57Fe,31P) coupling constants.
- Long T1 values.
In iron-containing compounds the following experiments can be helpful:BIBLIOGRAPHYIntensity gain 1H-57Fe factors:
- 1H-decoupled vs 1H-coupled 57Fe experiment.
- 1D 1H-57Fe INEPT experiments ( 01ORG5774 )
- 2D 1H-57Fe HMQC or HSQC experiments ( 86JACS5622 and 88JACS5661 ). Similar approaches using 31P decoupling ( 96MRC89 )
- 2D 57Fe-31P heteronuclear correlation experiments using phosphorus-detection ( 82JMR528-47 , 86JACS5622 , 88JACS5661 , and 88MRC895 ). Also analogous 1D INEPT 57Fe{31P} experiments have been reported.
NOE INEPT Inverse INEPT HMQC 16.4 30.8 171 5263
Interesting review: B91PRE102.
The Transition Metals NMR: B79HAR195, 00ENC730 .Examples of 57Fe NMR: 90JACS2804 , 90IC556-29 , 88HCA1116-71 , and 96ORG2469