S = 1 Spin State of Divalent Iron. II. A Mössbauer-Effect Study of Phthalocyanine Iron (II)

Measurements of the 57Fe Mössbauer spectrum of phthalocyanine iron(II) made at 4.2° and 100°K, with the sample in applied magnetic fields of 30 kOe, show that the electric field gradient at the iron nucleus is of positive sign and that there is no large asymmetry in the electric-field-gradient tensor. The major axis of the field-gradient tensor does not appear to be colinear with the magnetic symmetry axis, indicating that there is no orbital degeneracy in the molecule. The hyperfine field at the iron nucleus, measured in the plane of maximum magnetization, is estimated to be + 270 kOe.