2D NMR studies of paramagnetic diiron complexes

Li June Ming, Ho Gyeom Jang, Lawrence Que

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Diiron complexes of dinucleating ligands have been demonstrated to be good structural and spectroscopic models for the diiron-oxo proteins. Although such complexes show relatively sharp isotropically shifted 1H NMR resonances due to their fast electronic relaxation rates, detailed assignment of their isotropically shifted 1H NMR resonances has thus far not been achieved due to the difficulty in establishing bond connectivities on paramagnetic complexes. In this report, we present 2D COSY, TOCSY, and EXSY studies of the complex [Fe2(BPMP)(O2P(OPh)2)2]n+ (BPMP = 2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenol; n = 1, 2) in both its diferrous and mixed-valence states. The resonances due to the two distinct pyridine rings can be unambiguously assigned from the observation of bond-correlated cross signals in the 2D spectra due to the meta1-para-meta2 pyridyl proton connectivities. The 2D data used in connection with relaxation time measurements and the known crystal structure of the reduced complex allow the isotropically shifted proton resonances of the reduced complex to be conclusively assigned. The resonances of the diferrous and mixed-valence complexes can also be correlated by EXSY and saturation transfer experiments. This report represents the first detailed NMR study of model complexes for nonheme iron proteins by the use of 2D NMR techniques, demonstrating the versatility of NMR spectroscopy for the study of paramagnetic metal complexes.

Original languageEnglish
Pages (from-to)359-364
Number of pages6
JournalInorganic Chemistry
Volume31
Issue number3
Publication statusPublished - 1992 Dec 1
Externally publishedYes

Fingerprint

Protons
Nonheme Iron Proteins
Nuclear magnetic resonance
nuclear magnetic resonance
Structural Models
Coordination Complexes
Magnetic Resonance Spectroscopy
Observation
Ligands
proteins
valence
proton resonance
versatility
Proteins
Time measurement
Relaxation time
Nuclear magnetic resonance spectroscopy
pyridines
Crystal structure
relaxation time

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

2D NMR studies of paramagnetic diiron complexes. / Ming, Li June; Jang, Ho Gyeom; Que, Lawrence.

In: Inorganic Chemistry, Vol. 31, No. 3, 01.12.1992, p. 359-364.

Research output: Contribution to journalArticle

Ming, LJ, Jang, HG & Que, L 1992, '2D NMR studies of paramagnetic diiron complexes', Inorganic Chemistry, vol. 31, no. 3, pp. 359-364.
Ming, Li June ; Jang, Ho Gyeom ; Que, Lawrence. / 2D NMR studies of paramagnetic diiron complexes. In: Inorganic Chemistry. 1992 ; Vol. 31, No. 3. pp. 359-364.
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