ANISOTROPIC CHEMICAL SHIFTS IN COBALT (3) COMPLEXES

The 59Co NMR was studied in single crystals of a number of cobalt (III) complexes at room temperature. A procedure was developed for the numerical analysis of the spectra, and the chemical shift and quadrupole coupling tensors were determined. In cobaltocenium nitrate (e2qQ/h =165.6 Mc/sec) one shift tensor component was used to obtain an improved gyromagnetic ratio for 59Co: 7= 1.0035 kc/sec-G. For the substituted octahedral complexes trans-[Co en2Cl2] Cl·HCl·2H2O (e3qQ/h=71.7 Mc/sec); [Co(NH3)5CN]Cl2 (e2qQ/h=26.6 Mc/sec); [Co(NH3)4CO3]Br (e2qQ/h=18. 8 Mc/sec); and trans[Co en2(NO2)2]NO 3 (e2qQ/h=13.2 Mc/sec), a linear dependence of the shift anisotropy + 4.6%, -2.2%, +1.5%o, and +0.4%) on the quadrupole coupling constant was found. The molecular orbital theory was used to interpret the results.