Question
These compounds are commonly used to induce a paramagnetic change in the spins of nearby molecular systems during one technique. For 10 points each:
[10h] Name these non-solvent compounds used to resolve overlapping multiplets. A popularly used one of these compounds is formed from the coordination of three FOD (“fod”) ligands to a europium ion.
ANSWER: chemical shift reagents [accept lanthanide shift reagents; prompt on lanthanides]
[10e] Shift reagents improve the resolution of spectra produced by this technique, which uses a strong magnetic field to flip the spins of a chemical species’s nuclei.
ANSWER: nuclear magnetic resonance spectroscopy [or NMR spectroscopy]
[10m] Because it interacts with R and S enantiomers differently, the shift reagent Eu(hfbc)3 (“europium H-F-B-C-3”) is useful in determining this quantity in an NMR sample. This quantity represents the ratio of R- and S-labelled isomers in a racemic mixture.
ANSWER: enantiomeric excess [or ee; accept optical purity; accept optical activity]
<Kane Nguyen, Chemistry>
Summary
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