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) Å. 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.

Graphical abstractThe synthesis of three new Cu(II) and Co(II,III) complexes of different topologies was achieved upon the reaction of Cu(II) or Co(II) salts with H2L.Figure optionsDownload full-size imageDownload as PowerPoint slide