Abstract: | Investigation of the Hydrolytic Build‐up of Iron(III)‐Oxo‐Aggregates The synthesis and structures of five new iron/hpdta complexes [{FeIII4(μ‐O)(μ‐OH)(hpdta)2(H2O)4}2FeII(H2O)4]·21H2O ( 2 ), (pipH2)2[Fe2(hpdta)2]·8H2O ( 4 ), (NH4)4[Fe6(μ‐O)(μ‐OH)5(hpdta)3]·20.5H2O ( 5 ), (pipH2)1.5[Fe4(μ‐O)(μ‐OH)3(hpdta)2]·6H2O ( 7 ), [{Fe6(μ3‐O)2(μ‐OH)2(hpdta)2(H4hpdta)2}2]·py·50H2O ( 9 ) are described and the formation of these is discussed in the context of other previously published hpdta‐complexes (H5hpdta = 2‐Hydroxypropane‐1, 3‐diamine‐N, N, N′, N′‐tetraacetic acid). Terminal water ligands are important for the successive build‐up of higher nuclearity oxy/hydroxy bridged aggregates as well as for the activation of substrates such as DMA and CO2. The formation of the compounds under hydrolytic conditions formally results from condensation reactions. The magnetic behaviour can be quantified analogously up to the hexanuclear aggregate 5 . The iron(III) atoms in 1 ‐ 7 are antiferromagnetically coupled giving rise to S = 0 spin ground states. In the dodecanuclear iron(III) aggregate 9 we observe the encapsulation of inorganic ionic fragments by dimeric{M2hpdta}‐units as we recently reported for AlIII/hpdta‐system. |