Proton Spin—Spin Coupling Constants from the NMR Spectra of Paramagnetic Molecules

摘要: ``Chemical shifts'' for protons in the paramagnetic Ni II aminotroponeimineates are up to 250 times greater than shifts of analogous diamagnetic chelates or ligands. These increased attributed isotropic hyperfine contact interactions between and pπ spin densities transferred from aminotroponeimine ligand as result pπ—dπ bonding. Widths nuclear resonances these solution sufficiently narrow that many cases spin—spin (I·I) couplings can be resolved. The large separations different lead simple first‐order spectra which coupling constants obtained directly. Proton a number conjugated groups this way reported compared with values compounds. Close agreement is found. have also been first time more complex give rise prohibiti...