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

Abstract

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]·2H₂O (1) and [Cu(dpa)(4-meim)(5-meim)₂]·H₂O (2) were determined by single-crystal X-ray diffraction (H₂dpa = 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···Cu weak hydrogen-bonding interactions.

Graphical Abstract

The molecular structure of 2 with intramolecular C−H···Cu, C−H···π and hydrogen bonding interactions.

Keywords:

• Linkage isomerism
• Mixed ligand complex
• Cobalt(II) complex
• Copper(II) complex
• Diphenate complexes

Acknowledgements

We thank the Research Fund of the Eskişehir Osmangazi University (Project Number: 201319F01) and Ministry of Higher Education of Malaysia [grant number UM.C/HIR/MOHE/SC/12] for supporting this study.