Synthesis,structure, and electrochemistry of pyridinecarboxamide cobalt(III) complexes; the effect of bridge substituents on the redox properties |
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Authors: | Soraia Meghdadi Mehdi Amirnasr Mohammad H. Habibi Ahmad Amiri Vahid Ghodsi Azadeh Rohani Ross W. Harrington William Clegg |
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Affiliation: | 1. Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran;2. Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran;3. School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK |
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Abstract: | Two series of complexes of the types trans-[CoIII(Mebpb)(amine)2]ClO4 {Mebpb2− = N,N-bis(pyridine-2-carboxamido)-4-methylbenzene dianion, and amine = pyrrolidine (prldn) (1a), piperidine (pprdn) (2a), morpholine (mrpln) (3a), benzylamine (bzlan) (4a)}, and trans-[CoIII(cbpb)(amine)2]X {cbpb2− = N,N-bis(pyridine-2-carboxamido)-4-chlorobenzene dianion, and amine = pyrrolidine (prldn), X = PF6 (1b), piperidine (pprdn), X = PF6 (2b), morpholine (mrpln), X = ClO4 (3b), benzylamine (bzlan), X = PF6 (4b)} have been synthesized and characterized by elemental analyses, IR, UV–Vis, and 1H NMR spectroscopy. The crystal structure of 1a has been determined by X-ray diffraction. The electrochemical behavior of these complexes, with the goal of evaluating the effect of axial ligation and equatorial substitution on the redox properties, is also reported. The reduction potential of CoIII, ranging from −0.53 V for (1a) to −0.31 V for (3a) and from −0.48 V for (1b) to −0.22 V for (3b) show a relatively good correlation with the σ-donor ability of the axial ligands. The methyl and chloro substituents of the equatorial ligand have a considerable effect on the redox potentials of the central cobalt ion and the ligand-centered redox processes. |
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Keywords: | Bispyridylamide complexes of Co(III) Substituted N4-amido ligand Crystal structure Cyclic voltammetry |
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