DENSITY FUNCTIONAL-STUDY OF IRON(II)-PORPHINE

Electron densities and state energies have been calculated for iron(II)-porphine (porphinatoiron(II)) or Fe(II)P and for (meso-tetraphenyl-porphinato)iron(II) or FeTPP within the local density approximation. A ground state of 3E symmetry separated by 0.2 eV from the 3A first excited state has been found in both complexes. High spin as well as low spin states are calculated to be higher in energy than the triplet states contrary to ab initio results but in agreement with experiment. A full geometry optimization for the planar FeP has essentially confirmed the previously assumed geometry. The calculated electric field gradient at the iron nucleus is compared with Mossbauer data. Theoretical static density maps are compared with the experimental map for FeTPP. The results strongly suggest that the true ground state of crystalline FeTPP is a mixture of low lying triple states.