Synthesis, Crystal Structure, and Magnetic Properties of Amidate and Carboxylate Dimers of Ruthenium

Solvothermal and microwave-assisted methods have been used to prepare several amidate and carboxylate complexes of the type [Ru2X(μ-NHOCC6H3-3,5-(OMe)2)4]n [X = Cl (1), Br (2), I (3)] and [Ru2X(μ-O2CC6H3-3,5-(OMe)2)4]n [X = Cl (4), Br (5), I (6)]. Complexes 4–6 have also been obtained by conventional synthesis which is ineffective to prepare the amidate compounds. However, single crystals of complexes 1–5 were obtained using the solvothermal method. The single crystal X-ray structure determination of compounds 1–5 have been carried out. All complexes display a paddlewheel-type structure with the metal atoms connected by four bridging amidate or carboxylate ligands. Chloride, bromide, or iodide anions connect the dimetallic units, producing one-dimensional zigzag chains. The magnetic properties of all compounds were studied. The magnetic moment at room temperature are in accordance with an electronic configuration with three unpaired electrons σ2π4δ2(π*δ*)3 per dimer unit. The fit of the magnetic data suggests the existence, in these complexes, of a weak antiferromagnetic intermolecular interaction between the diruthenium units mediated by the halide ligand and an appreciable zero-field splitting in the diruthenium moieties.