Tetranuclear copper(II) complexes incorporating short and long metal-metal separations: synthesis, structure and magnetism

Synthesis, structural and magnetic characterization of tetranuclear [(Cu2L)(2)B] complexes [where H3L is the Schiff's-base ligand, 1,3-bis(salicylideneamino)propan-2-ol; B is the dipyrazolate entities: methylenebis(3,5-dimethylpyrazolate) (mbdpz) or 4,4'-bi-3,5-dimethylpyrazolate (mdpz)] are reported. The structures reveal short intra- and inter-molecular Cu ... Cu separations (ca. 3.4 Angstrom), in combination with long intramolecular copper distances (ca. 10 Angstrom). The magnetic behaviour of [(Cu2L)(2)(mbdpz)] (1) is indicative of an intramolecular antiferromagnetic interaction between the copper(II) centres [2J = -460 cm(-1)], whilst that of [(Cu2L)(2)(mdpz)] (2) is characteristic of an antiferromagnetically coupled system with intramolecular coupling in the order of 2J = -380 cm(-1), with the presence of a further intermolecular interaction indicated.