On the interpretation of Mössbauer isomer shifts of iron-organic compounds.

Analysis of the available data for several classes of homo- and heteroleptic iron-organic compounds has shown that coefficient ∇IS/aID = 0.04 mm s−1 pm−1 can be applied to describe the interrelation between the Mössbauer isomer shift and average interatomic distance between iron and the atoms of its coordination polyhedron. An additional increment was used to describe changes in the isomer shift that are not related to changes in the environment of iron or in the corresponding interatomic distances. This increment characterizes the filling of hybridized 4s4pm3dn orbitals with electrons. To calculate the increment, the value of 1.4 mm s−1 was used, which characterizes the difference between isomer shifts of iron with fully filled and half-filled hybridized shells. To compare the isomer shifts of iron compounds with ligands of different sizes, the corrections for these sizes were used. [ABSTRACT FROM AUTHOR]