SENSITIVE MEASUREMENT OF ONE-BOND CARBON-CARBON SPIN COUPLING-CONSTANTS AT NATURAL ISOTOPE ABUNDANCE

Two new experiments for the assignment and determination of (1)J(C-13, C-13) coupling constants of H-C-C fragments at natural isotope abundan ce are presented which exploit proton equilibrium polarization and pro ton signal intensity, The first experiment, which represents a J-resol ved modification of the proton-detected INEPT-INADEQUATE experiment, y ields highly accurate values of the coupling constants. The second exp eriment, which features an additional double-quantum evolution period, also yields the coupling constants and allows an unambigous assignmen t, This last experiment was implemented as a 2D experiment, although i t could be run as a 3D experiment.