Nitrogen-15 Magnetic Resonance Spectroscopy. X. Angular Dependence of Vicinal ^(15)N-H Coupling Constants in Amino Acids

Abstract

In contrast to the extensive investigations of the dependence of vicinal proton-proton and protonfluorine coupling constants on dihedral angle, relatively little is known about the angular dependence of vicinal proton-nitrogen couplings in saturated systems. The principal reasons for this are experimental difficulties associated with the quadrupole-induced relaxation of ^(14)N and the relatively small magnitudes of ^(14)N-H coupling constants. However, Terui, Aono, and Tori have recently demonstrated a geometrical dependence of the vicinal ^(14)N-H coupling in compounds of types 1 and 2 for dihedral angles of 0, 60, and 120º.

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