Di-, tetra- and hexanuclear iron(III), manganese(II/III) and copper(II) complexes of Schiff-base ligands derived from 6-substituted-2-formylphenols

Acyclic Schiff base ligands, derived from the condensation of 2,3-disubstituted benzaldehydes and 1,3-diaminopropan-2-ol, react with iron(II/III), manganese(II/III) and copper(II) salts to give di-, tetra-and hexanuclear complexes [Fe-2(III)(L5)(2)]center dot 2MeOH (1), [Fe-4(III)(mu(3)-OMe)(2)(HL4)(2)Cl-2] (2), [(Mn2Mn2III)-Mn-II(mu-OMe)(2)(HL4)(2)(DMF)(2)]center dot 2DMF (3) and [Cu-6(II)(L5)(2)(mu(5)-SO4)(2)(mu-SO4)(MeOH)(2)]center dot H2O center dot 15.5(MeOH)center dot 15.5(MeCN) (4). All compounds have been characterised by X-ray crystallography. Variable-temperature solid-state dc magnetisation studies have been performed in the temperature range 1.8-300 K. Antiferromagnetic interactions are present in all the compounds. The dinuclear compound 1 has a zero total spin ground state with J = -9.66(1) cm(-1) and g = 2.07(1). The magnetic data for the tetranuclear compounds 2 and 3 have been interpreted using a tetranuclear butterfly model (b = body, w = wingtip) with the parameters: J(wb) = -9.35(4) cm(-1), J(bb) = -6.02(7) cm(-1), zJ' = -0.21(4) cm(-1) and g = 2.03(1) for 2; and J(wb) = -3.40(3) cm(-1), J(bb) = -8.11(7) cm(-1), zJ' = -0.042(2) cm(-1) and g = 2.0 (fixed) for 3. The hexanuclear compound 4 contains two {Cu-3(L-5)(MeOH)} units linked by three sulfate ligands: antiferromagnetic interactions are present in each trinuclear unit leading to two S = 1/2 motifs which do not or only very weakly interact across the sulfate bridges.