Nuclear Magnetic Resonance Spectral Chromatography: New Superior Paramagnetic Shift Reagents for Spectral Clarification.
Abstract
Nuclear magnetic resonance spectral chromatography is defined as the separation and clarification of NMR spectral 'bands' of a single compound or a mixture by specific interaction of one or more moieties with a soluble coordinatively unsaturated paramagnetic species acting as a Lewis acid. Addition of certain lanthanide complexes of 2,2,6,6-tetramethyl-3,5-heptane-dione(thd) or 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione (fod) results in greatly shifted and simplified NMR spectra of various organic compounds. Complexes of fod with europium (III) and praseodymium (III) are far superior to those of thd because they are much more soluble in organic solvents and are better Lewis acids owing to the electron withdrawing effect of the fluorines. Eu(fod)3 forms complexes even with such poor Lewis bases as di-n-butylether. Consequently, the fod chelates are effective for spectral clarification for much broader classes of compounds and concentration ranges than the thd chelates. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1970
- Accession Number
- AD0722440
Entities
People
- Robert E. Sievers
- Roger E. Rondeau
Organizations
- Air Force Research Laboratory