Synthesis, structure and magnetic properties of carboxylate-bridged polynuclear copper(II)–lanthanide(III) rings: [Ln(H2O)5(CuL)2][CuL]·8H2O (Ln=La, Ce)

Reaction of Na[CuL] (H3L = the Schiff base derived from 5-bromosalicylaldehyde and glycylglycine) with Ln(NO3)3 leads to the formation of the title complexes [Ln(H2O)5(CuL)2][CuL] · 8H2O (Ln = La (1) and Ce (2)), which contain ring-like hexanuclear [Ln2(H2O)10(CuL)4]2+ cations. The Ln(III) cations in 1 and 2 are coordinated by five water molecules, one carbonyl oxygen and three carboxylic oxygen atoms, and the copper(II) cations are coordinated by one phenolic oxygen, one carboxylate oxygen atom, one deprotonated amide nitrogen atom and one imino nitrogen atom. Complex 1 exhibits a ferromagnetic interaction and 2 exhibits an antiferromagnetic interaction in the solid state.