ENDOR proton coordinates

As a complementary investigation to the ENDOR determination of proton coordinates in lanthanum nicotinate dihydrate (see section 3.2), Davidson et al. (1981) have observed NEQ resonance of three inequivalent N (/ = 1) on pyridine sites and four hydrate D I = 1) nuclei at 77 K in this compound. They made use of a highly sensitive technique in which energy fed into the NEQ resonances in zero magnetic field is transferred internally to nearby protons, and then detected by proton NMR following rapid movement of the sample into a field of 1 T. The NEQ... 

Henderson TA, Hurst GC, Kreilick RW. 1985. Angle-selected ENDOR spectroscopy, 2 determination of proton coordinates from a polycrystalline sample of bis(2,4-pentanedionato)copper(II). J Am Chem Soc 107 7299-7303. 

Since the unpaired electron in transition metal complexes is generally localized near the central ion and the ligand atoms in the first coordination sphere, summation in (5.5) over these nuclei is often sufficient. In this approximated form, the point-dipole model has frequently been applied in ENDOR studies of transition metal complexes to determine the proton positions from their hfs tensors (Sect. 6). In some cases the accuracy of this method has turned out to be significantly higher than that of an X-ray diffraction analysis62,130 131). 

EPR and proton ENDOR measurements on Cu(II)-doped zinc acetate have been reported by Atherton and Horsewill215). In contrast to the pure copper salt, which consists of copper pairs, zinc acetate has a monomeric structure in which two water molecules are coordinated to each zinc ion216), as illustrated in Fig. 40. The magnetic parameters are summarized in Table 13. Both the g and ACu tensor obtained from single crystal and... 

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