Structures and magnetic behaviour of hydroxo-bridged Cr III aggregates: [Cr 4(μ-OH) 4(hpdta) 2] 2− and [Cr 6(μ-OH) 8(hpdta) 2(en) 2

Abstract

The syntheses and crystal structures of the tetra- and hexanuclear Cr III aggregates ( enH 2 ) [ Cr 4 ( μ - OH ) 4 ( hpdta ) 2 ] · 5 1 2 H 2 O ( 1 a ) , [Ba(OH 2) 5{Cr 4(μ-OH) 4(hpdta) 2}] · 13H 2O ( 1b) [Cr 6(μ-OH) 8(hpdta) 2(en) 2] · 10H 2O ( 2a) and [Cr 6(μ-OH) 8(hpdta) 2(en) 2] · 14H 2O ( 2b) (H 5hpdta = 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 Fe III aggregates, is not yet possible in the case of Cr III.