Mössbauer Isomer Shifts of Ferrous Phenanthroline and Related Complexes

Abstract

The center shifts at liquid‐nitrogen temperature of a number of substituted phenanthroline complexes fell in a rather narrow range from about 0.50 to 0.53 mm/sec with a trend to larger values for the more electron‐withdrawing substituents. Among the other ferroin‐type complexes, the two with nonaromatic ligands had appreciably larger center shifts than the aromatics. The nonbridged aromatic ligands all gave smaller center shifts than the phenanthrolines suggesting greater covalency. In most cases the temperature dependence of the center shift was anomalously small, and several possible causes of this are suggested.