Two-dimensional 1H NOESY data are routinely used to assign specific stereo-isomers based on the proton nuclear Overhauser effects (NOE's) which are strongly correlated to inter-proton distances through space. For example, NOE's may be observed for cis- protons across a double bond but not observed for trans- protons. The same technique can be used with 19F in fluorinated compounds to gauge the inter-fluorine distance and assign stereochemistry. The figure below shows the 19F NOESY spectrum of a fluorine containing cobalt complex.

Thank you to Graham Lee (of Dr. R.T. Baker's research group at the University of Ottawa) for kindly providing the sample and sharing his data.
No comments:
Post a Comment