On the orbital ground state and the magnitude of the quadrupole interaction in some high-spin iron(II) pyridine complexes

Abstract

Mössbauer spectra of the pseudooctahedral complex trans-Fe(pyridine) 4(NCS) 2 have been measured at 4.2°K in applied magnetic fields of up to 60 kG. The principal component of the electric field gradient tensor is positive and consistent with a 5B 2g ground electronic state in a tetragonal local site symmetry. The sign of the quadrupole interaction is discussed in relation to a number of recent investigations in which orbital ground terms are assigned solely on the basis of the magnitude and temperature of the quadrupole interaction.