Syntheses, crystal structures and magnetic properties of [2 × 1 + 1 × 2] heterotetrametallic and [1 × 1 + 1 × 1] heterodimetallic cocrystals of copper(II) and iron(II/III)

The present work reports syntheses, crystal structures and variable-temperature magnetic properties of three copper(II)–iron(II/III) compounds [{CuIIL1}{FeIIIL1(H2O)2}](ClO4) (1), [{CuIIL1FeII(H2O)3}{CuIIL1}2](ClO4)2 (2) and [{CuIIL2FeII(H2O)3}{CuIIL2}2](ClO4)2·H2O·CH3COCH3 (3), where H2L1 = N,N′-ethylenebis(3-ethoxysalicylaldimine) and H2L2 = N,N′-o-phenylenebis(3-ethoxysalicylaldimine). Compounds 2 and 3 are tetrametallic [2 × 1 + 1 × 2] cocrystals of one diphenoxo-bridged dinuclear CuIIFeII and two mononuclear CuII moieties, while compound 1 is a dimetallic [1 × 1 + 1 × 1] cocrystal of one mononuclear FeIII and one mononuclear CuII moieties. The overall topology of 1 is one-dimensional. Tetrametallic (in 2 and 3) and one-dimensional (in 1) self-assemblies are generated due to weak noncovalent interactions. Variable-temperature magnetic susceptibility measurements reveal that iron(II) or iron(III) centers in 1–3 remain in high-spin state. Compounds 2 and 3 exhibit weak antiferromagnetic interaction; the J values in the dinuclear core are −22.5 and −13.7 cm−1, respectively, compound 1 exhibits very weak antiferromagnetic interaction (J = −0.25 cm−1) propagated through the weak noncovalent bonds.