ИСТИНА

Considering published structural and Mӧssbauer data for selected iron oxocompounds [2], we observed, that for the compounds with similar local spatial structure of iron coordination polyhedral isomer shift (IS) is proportional to average interatomic Fe-O distance (aIDFe-O), proportionality coefficient remaining the same for different types of polyhedra. For the same aIDFe-O IS incrementally decreases with increasing coordination number, spatial structure making less contribution. Moreover, IS depends upon ability of surrounding oxygen ions to promote electron density toward the iron nucleus: each unshared O2- -ion gives an additional negative impact into IS compared to shared one.