Invited reviewNatural iron oxalates and their analogous synthetic counterparts: A review

Four iron-containing natural oxalates, usually classified as organic minerals, are known (humboldtine, minguzzite, stepanovite and zhemchuzhnikovite). Their occurrences and general properties are presented and briefly discussed. The subsequent part of the review is devoted to the discussion of synthetic oxalato-complexes, analogous to these natural species, including usual synthetic procedures and a thorough analysis of their crystallographic and structural peculiarities. The thermal, spectroscopic and magnetic properties of these complexes are also analyzed in detail and comparisons with other closely related complexes are also included in the discussions.