Cobalt(II) and copper(II)-diphenate complexes with 4-methylimidazole: linkage isomerism and weak C-H•••Cu interaction

The molecular structure of 2 with intramolecular C-H center dot center dot center dot Cu, C-H center dot center dot center dot pi and hydrogen bonding interactions. New Co(II) and Cu(II) diphenate complexes with 4-methylimidazole were synthesized and characterized through elemental analysis, magnetic susceptibilities, and IR spectroscopic studies. The crystal structures of [Co(dpa)(5-meim)(4)]center dot 2H(2)O (1) and [Cu(dpa)(4-meim)(5-meim)(2)]center dot H2O (2) were determined by single-crystal X-ray diffraction (H(2)dpa = diphenic acid, 4-meim = 4-methylimidazole and 5-meim = 5-methylimidazole). In 1, Co(II) has distorted octahedral geometry with four 5-meim and one diphenate ligands. Complex 2 has distorted trigonal bipyramidal geometry with one 4-methylimidazole, two 5-methylimidazole, and one diphenate ligands. In the complexes, the diphenate is coordinated to the metal(II) ions via the deprotonated oxygens of carboxylate as a bidentate ligand. The 4-meim and 5-meim linkage isomers within the same complex are found, and this complex is an unusual example. Moreover, another interesting feature of 2 is the presence of C-H center dot center dot center dot Cu weak hydrogen-bonding interactions.