Copper(II) and cobalt(II,III) complexes of a new carboxylic-functionalized arylhydrazone of 5,5-dimethylcyclohexane-1,3-dione

Upon reaction of 2-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)benzoic acid (H2L, 1) with Cu(NO3)2·2.5H2O and imidazole (im) or ethylenediamine (en), the mononuclear {[Cu(H2O)2(ed)2]2+(HL−)2}·6H2O (2) and binuclear [Cu(1κN,O2:2κO-L)(im)]2 (3) complexes, respectively, were obtained. A trinuclear mixed-valence cobalt(II,III) complex, [{Co(1κN,O2-L)(1κN,O2:2κO-μ-L)}Co0.5(H2O)2]2·10H2O, (4·10H2O) is formed when Co(NO3)2·6H2O reacts with H2L in methanol. Compounds 1–4 were fully characterized by IR spectroscopy, ESI-MS, elemental and single-crystal X-ray diffraction analyses. The crystal structure of 2 consists of two anionic HL− moieties along with the distorted octahedral [Cu(H2O)2(en)2]2+ complex cation. The Cu(II) centers in 3 display distorted square pyramid coordination modes (τ5 = 0.2) with a Cu⋯Cu distance within the Cu2O2 core of 3.2490(18) A. In 4 the cobalt centers display octahedral geometries. The structural units in 3 and 4 are combined into infinite 1D chains along the crystallographic b and a axis, respectively, by means of intermolecular H contacts. In 4 the structure further extends into the second dimension by means of extensive H-bonding interactions involving water molecules.