DENSITY FUNCTIONAL CALCULATIONS OF EPR HYPERFINE COUPLING CONSTANTS OF SOME FIRST ROW TRANSITION METAL COMPLEXES

摘要

We have calculated the EPR spectral parameter hyperfine coupling constants of some first row transition metal complexes namely [Fe(CO)_5]~+, [Mn(CN)_5NO]~(2+) and [Co(CO)4] using Density Functional Theory. For these calculations, BHPW91, B3LYP, B3PW91, BLYP, BPW91. BP86, BHP86 functionals have been used. The hyperfine coupling constants values obtained from different density functionals have been found in the order BHPW91 > BHP86 > BHLYP > B3PW91 > BLYP > BP86 > BPW91> B3LYP > EXP for [Fe (CO)_5]~+, BHPW91 > BHP86 > BHLYP > BLYP > BP86 > BPW91 > B3PW91 > B3LYP >EXP for [Mn (CN)_5NO]~(2-) and BHPW91 > BHP86 > BHLYP > BLYP > BP86 > BPW91 > B3PW91 > B3LYP > EXP for [Co(CO)_4] complex. We have inferred that DFT functional B3LYP is best functional for the estimation of hyperfine coupling constant for [Fe(CO)_5]~+, [Mn (CN)_5NO]~(2-) and [Co(CO)4 metal complexes.