POLYCRYSTALLINE CO-59 NMR-STUDIES OF METAL-LIGAND INTERACTION IN AXIALLY-SYMMETRICAL DIAMAGNETIC CO(III) COMPLEXES - CORRELATION OF DELTA(CO-59) WITH NQCC DELTA-E(AV)

The polycrystalline Co-59 NMR spectra (1/2 <-- --> -1/2 transition) of the diamagnetic cobalt(III) complexes Na3[Co(NO2)6] and trans-[Co(en)2(NO2)2]NO3 Were measured at 7.1 and 9.5 T. It is demonstrated that for axially symmetric diamagnetic cobalt(III) complexes the Co-59 chemical shielding anisotropy (CSA) is semiquantitatively correlated (r = 0.998) with the product of the nuclear quadrupole coupling constant (NQCC) and the inverse of the weighted average of the first d-d electronic transition energies (DELTAE(av)) through the similarity of the d-orbitals population imbalance in the expressions for the CSA and the NQCC. The application of the correlation in the determination of the orbital reduction factor ratio for D4h complexes containing nitrogen ligating atoms is presented.