Solid-state NMR of a paramagnetic DIAD-FeII catalyst: sensitivity, resolution enhancement, and structure-based assignments.
A general protocol for the structural characterization of paramagnetic molecular solids using solid-state NMR is provided and illustrated by the characterization of a high-spin Fe(II) catalyst precursor. We show how good NMR performance can be obtained on a molecular powder sample at natural abundance by using very fast (>30 kHz) magic angle spinning (MAS), even though the individual NMR resonances have highly anisotropic shifts and very short relaxation times. The results include the optimization of broadband heteronuclear (proton-carbon) recoupling sequences for polarization transfer; the observation of single or multiple quantum correlation spectra between coupled spins as a tool for removing the inhomogeneous bulk magnetic susceptibility (BMS) broadening; and the combination of NMR experiments and density functional theory calculations, to yield assignments.
Kervern
Gwendal
G
Laboratoire de Chimie, UMR 5182 CNRS-ENS Lyon, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
Pintacuda
Guido
G
Zhang
Yong
Y
Oldfield
Eric
E
Roukoss
Charbel
C
Kuntz
Emile
E
Herdtweck
Eberhardt
E
Basset
Jean-Marie
JM
Cadars
Sylvian
S
Lesage
Anne
A
Copéret
Christophe
C
Emsley
Lyndon
L
D000465:Algorithms; D016880:Anisotropy; D002244:Carbon / Q000737:chemistry; D002247:Carbon Isotopes / Q000737:chemistry; D002384:Catalysis; D002413:Cations, Divalent; D018360:Crystallography, X-Ray; D003903:Deuterium / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008280:Magnetics; D009942:Organometallic Compounds / Q000737:chemistry*; D011522:Protons; D011789:Quantum Theory; D013113:Spin Labels
D002247:Carbon Isotopes; D002413:Cations, Divalent; D009942:Organometallic Compounds; D011522:Protons; D013113:Spin Labels; D002244:Carbon; D003903:Deuterium; D007501:Iron