FPT-CNDO 2 STUDIES OF CO-59 CHEMICAL SHIELDING CONSTANTS IN HEXACOORDINATED DIAMAGNETIC CO(III) COMPLEXES/

The Co-59 nuclear shielding constants of five hexacoordinated diamagne tic cobalt(III) complexes have been calculated using a semiempirical m olecular orbital method within the framework of the finite perturbatio n theory, the FPT-CNDO/2 method. Experimental and calculated chemical shifts referenced to the cobalticyanide anion gave good agreement. The difference between the calculated and the experimental chemical shift s is attributed to the underestimation of the radial factor. The origi n of the shielding on the cobalt nucleus is discussed in terms of the 3d orbital population. The shielding anisotropy in the compounds with low symmetry is also surveyed.