Cobalt(II) complexes with pyridine and 5-[(E)-2-(aryl)-1-diazenyl]-quinolin-8-olates: synthesis, electrochemistry and X-ray structural characterization

Abstract

Nine new cobalt(II) compounds, trans-[Co(LPAQ)2(Py)2] (1), trans-[Co(LPAQ)2(3-MePy)2] (2), tran s-[Co(LMeAQ)2(Py)2] (3), trans-[Co(LOMeAQ)2(Py)2] (4), trans-[Co(LOEtAQ)2(Py)2]·2(H2O) (5), tran s-[Co(LCAQ)2(Py)2] (6), trans-[Co(LBAQ)2(Py)2] (7), ci s-[Co(LBAQ)2(3-MePy)2] (8a) and tran s-[Co(LBAQ)2(3-MePy)2]·2(3-MePy) (8b) (primary ligand: LXAQ = substituted 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olate; secondary ligands: Py = pyridine, 3-MePy = 3-methylpyridine), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy. Magnetic measurements of the cobalt compounds were performed in solution by 1H NMR spectroscopy using the Evans’ method while their redox properties were studied by cyclic voltammetry. Single-crystal X-ray diffraction analysis of the compounds revealed their octahedral geometries and trans configuration, except for 8a, which has a cis configuration. Intermolecular noncovalent interactions were detected, π···π interactions in 5, C – H···π interactions in 2 and C – H···π edge-to-face (T-shaped) arrangements in 3, 4, 6, and 7.