Advances in the use of Lanthanide Enolates as Nuclear Magnetic Resonance Shift Reagents

Abstract

The use of lanthanide enolates as NMR shift reagents is described. Strategies to reduce broadening in the NMR spectrum with paramagnetic lanthanide ions are discussed. Recent studies of achiral donors are presented. Recent studies in which lanthanide enolates are used for structural and conformation analysis are described. The use of paramagnetic and diamagnetic chiral lanthanide complexes for analysis of enantiopurity by NMR spectroscopy is discussed. Recent studies in which NMR spectroscopy is used to characterize lanthanide β‐diketonate complexes are described.

Paramagnetic NMR Shifts of Tris-Hypersilanide Early f-Block Metal(III) Complexes

“…f-Block metal complexes have been exploited in a wide range of applications that take advantage of their remarkable magnetic and optical behaviour, 1 including chiral shift reagents [2][3][4] and PARASHIFT tags for Magnetic Resonance Imaging (MRI), [5][6][7] emissive probes for microscopy [8][9][10] and biomolecules, [11][12][13][14][15][16] and in determining spin-spin coupling in multi-metallic systems. [17][18][19] Nuclear Magnetic Resonance (NMR) spectroscopy is widely used to study these parameters and is also a useful technique to assess purity, to investigate exchange coupling and dynamic processes, and to extract kinetic and thermodynamic parameters.…”

Tris-Silanide f-Block Complexes: Insights into Paramagnetic Influence on NMR Chemical Shifts

“…f-Block metal complexes have been exploited in a wide range of applications that take advantage of their remarkable magnetic and optical behavior . These applications include chiral shift reagents − and PARASHIFT tags for magnetic resonance imaging (MRI), − emissive probes for microscopy − and biomolecules, − and in determining spin–spin coupling in multimetallic systems. − Nuclear magnetic resonance (NMR) spectroscopy is widely used to study these parameters and is also a useful technique to assess purity, to investigate exchange coupling and dynamic processes and to extract kinetic and thermodynamic parameters . As the vast majority of f-block ions are paramagnetic, the nuclear hyperfine interaction with unpaired electrons in valence f-orbitals give NMR spectra with significant paramagnetic shifts and line broadening. − While the 1 H NMR spectra of paramagnetic f-block complexes can often be assigned and correlated with calculated values to benchmark electronic structures, less receptive heteroatomic nuclei often give intractable spectra; thus, systematic investigations are rare …”

“…f-Block metal complexes have been exploited in a wide range of applications that take advantage of their remarkable magnetic and optical behavior. 1 These applications include chiral shift reagents 2 − 4 and PARASHIFT tags for magnetic resonance imaging (MRI), 5 − 7 emissive probes for microscopy 8 − 10 and biomolecules, 11 − 16 and in determining spin–spin coupling in multimetallic systems. 17 − 19 Nuclear magnetic resonance (NMR) spectroscopy is widely used to study these parameters and is also a useful technique to assess purity, to investigate exchange coupling and dynamic processes and to extract kinetic and thermodynamic parameters.…”