X-RAY-DIFFRACTION STUDY OF THE ELECTRONIC GROUND-STATE OF (MESO-TETRAPHENYLPORPHINATO)IRON(II)

The charge distribution in crystalline (meyo-tetraphenylporphinato)iron(II) has been derived from 10 154 intensity data measured at 120 (5) K. Crystal data are a = 14.992 (2) Å, c = 13.778 A, Z = 4, space group I42d. The data have been analyzed with the aspherical-atom multipole formalism including anharmonic thermal parameters for the iron atom. The deformation density maps indicate preferential occupancy of the d and d-, orbitals of the iron atom, a conclusion confirmed by the d-orbital populations derived from the aspherical-atom multipole refinement. The results are in agreement with an SCF-C1 calculation by Rohmer* and an INDO-CI calculation by Edwards, Weiner, and Zerner2 and support the 3A2g state as the leading contributor to the ground state of the complex. The ground-state assignment is in contrast to results on the intermediate spin complex iron(II) phthalocyanine, for which the electron density indicates a 3Eg ground state.3 The difference is attributed to the effect of short intermolecular Fe-N contacts in crystalline iron(II) phthalocyanine on the relative order of closely spaced energy levels. © 1990, American Chemical Society. All rights reserved.