Structures and magnetic behaviour of hydroxo-bridged CrIII aggregates: [Cr4(μ-OH)4(hpdta)2]2− and [Cr6(μ-OH)8(hpdta)2(en)2]

The syntheses and crystal structures of the tetra- and hexanuclear CrIII aggregates Click to view the MathML source, [Ba(OH2)5{Cr4(μ-OH)4(hpdta)2}] · 13H2O (1b) [Cr6(μ-OH)8(hpdta)2(en)2] · 10H2O (2a) and [Cr6(μ-OH)8(hpdta)2(en)2] · 14H2O (2b) (H5hpdta = 2-hydroxypropane-1,3-diaminetetraacetic acid) are reported and discussed. The antiferromagnetic interactions mediated by the bridging hydroxo ligands have been quantified. The fact that there are only a few such examples in the literature with similar bridges leads to the conclusion that a meaningful magnetostructural correlation, such as that recently proposed for oxo- and hydroxo-bridged FeIII aggregates, is not yet possible in the case of CrIII