User:Benjah-bmm27/degree/2/CJA

=NMR, CJA= "Introduction to NMR Spectroscopy"

Overview

 * Nuclear magnetic resonance
 * NMR spectroscopy

Fundamentals

 * Gyromagnetic ratio

Chemical shift

 * Chemical shift

NMR active nuclei

 * Proton NMR
 * Carbon-13 NMR
 * Fluorine-19 NMR
 * Phosphorus-31 NMR
 * Platinum-195 NMR

Coupling

 * J-coupling

One bond coupling

 * e.g. 13C—1H in CHCl3:
 * 1JCH ≈ 120 Hz

Two bond (geminal) coupling

 * e.g. bridgehead CH2 in norbornene:
 * 2JHH ≈ 10–18 Hz

Three bond (vicinal) coupling

 * if rotation about C–C is free (e.g. e.g. H–C–C–H in ethyl iodide), 3JHH ≈ 8 Hz
 * if rotation is restricted, can predict 3JHH from dihedral angle &phi; with the Karplus equation: 3JHH = &alpha; cos2(&phi;)
 * 3JHH is maximal (i.e. 3JHH = &alpha;) where &phi; = 0° or 180°,

Benzene rings

 * 3JHH, ortho ≈ 8 Hz
 * 4JHH, meta ≈ 2 Hz
 * 5JHH, para ≈ 0 Hz

Alkenes

 * 3JHH, trans ≈ 16 Hz
 * 3JHH, cis ≈ 8 Hz
 * 2JHH, gem ≈ 5 Hz

Equivalence

 * Chemical equivalence
 * Magnetic equivalence

Fluxionality

 * Fluxionality
 * Berry pseudorotation: PF5 animation in Jmol

Technical details

 * Relaxation (NMR)

Beyond the scope of the course

 * Larmor precession
 * Keeler lectures
 * Understanding NMR Spectroscopy by James Keeler