Synthesis, characterization, and redox behavior of new dicobalt complexes having monoanionic imine/oxime-type ligands

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

New dicobalt complexes, [CoIII 2LBr4], with monoanionic ligands (L) have been synthesized by the reaction of a tetraamine and oximes, followed by an aerobic reaction with CoBr2·6H2O. The complexes were characterized by elemental analyses, IR, ESR, and NMR as well as mass spectroscopies. The redox behavior of the complexes was examined in DMF by means of cyclic voltammetry in comparison with that of the corresponding mononuclear complex. Redox waves identified to CoIII/CoII and CoII/CoI for [CoIII 2L] were observed at -0.19 V and -0.69 V vs Ag/AgCl, respectively. These potentials are quite similar to those for the corresponding mononuclear complex. An electrogenerated [Co1 2L] species reacts with methyl p-toluenesulfonate to give an organocobalt complex. Two-electron reduction of the dinuclear organocobalt compound yields an unstable intermediate that undergoes rapid decomposition by cleavage of the cobalt-carbon bond. The dimethylated complex, which has cobalt-carbon bonds at one axial site of each cobalt, was disproportionated to a tetramethylated complex, involving two cobalt-carbon bonds at both axial sites, and a dicobalt(I) species by two-electron reduction. The tetramethylated cobalt complex was inactive for an electrochemical reduction, but transformed into the dimethylated complex via cleavage of the cobalt-carbon bonds upon electrochemical oxidation.

Original languageEnglish
Pages (from-to)1553-1558
Number of pages6
JournalBulletin of the Chemical Society of Japan
Volume75
Issue number7
DOIs
Publication statusPublished - Jul 2002

Fingerprint

Imines
Oximes
Cobalt
Ligands
Carbon
Electrons
Electrochemical oxidation
Cyclic voltammetry
Paramagnetic resonance
Oxidation-Reduction
Nuclear magnetic resonance
Spectroscopy
Decomposition

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Cite this

@article{f0b0dac5e13348e5b2af764e5a18eb1d,
title = "Synthesis, characterization, and redox behavior of new dicobalt complexes having monoanionic imine/oxime-type ligands",
abstract = "New dicobalt complexes, [CoIII 2LBr4], with monoanionic ligands (L) have been synthesized by the reaction of a tetraamine and oximes, followed by an aerobic reaction with CoBr2·6H2O. The complexes were characterized by elemental analyses, IR, ESR, and NMR as well as mass spectroscopies. The redox behavior of the complexes was examined in DMF by means of cyclic voltammetry in comparison with that of the corresponding mononuclear complex. Redox waves identified to CoIII/CoII and CoII/CoI for [CoIII 2L] were observed at -0.19 V and -0.69 V vs Ag/AgCl, respectively. These potentials are quite similar to those for the corresponding mononuclear complex. An electrogenerated [Co1 2L] species reacts with methyl p-toluenesulfonate to give an organocobalt complex. Two-electron reduction of the dinuclear organocobalt compound yields an unstable intermediate that undergoes rapid decomposition by cleavage of the cobalt-carbon bond. The dimethylated complex, which has cobalt-carbon bonds at one axial site of each cobalt, was disproportionated to a tetramethylated complex, involving two cobalt-carbon bonds at both axial sites, and a dicobalt(I) species by two-electron reduction. The tetramethylated cobalt complex was inactive for an electrochemical reduction, but transformed into the dimethylated complex via cleavage of the cobalt-carbon bonds upon electrochemical oxidation.",
author = "Hisashi Shimakoshi and Masaomi Koga and Yoshio Hisaeda",
year = "2002",
month = "7",
doi = "10.1246/bcsj.75.1553",
language = "English",
volume = "75",
pages = "1553--1558",
journal = "Bulletin of the Chemical Society of Japan",
issn = "0009-2673",
publisher = "The Chemical Society of Japan",
number = "7",

}

TY - JOUR

T1 - Synthesis, characterization, and redox behavior of new dicobalt complexes having monoanionic imine/oxime-type ligands

AU - Shimakoshi, Hisashi

AU - Koga, Masaomi

AU - Hisaeda, Yoshio

PY - 2002/7

Y1 - 2002/7

N2 - New dicobalt complexes, [CoIII 2LBr4], with monoanionic ligands (L) have been synthesized by the reaction of a tetraamine and oximes, followed by an aerobic reaction with CoBr2·6H2O. The complexes were characterized by elemental analyses, IR, ESR, and NMR as well as mass spectroscopies. The redox behavior of the complexes was examined in DMF by means of cyclic voltammetry in comparison with that of the corresponding mononuclear complex. Redox waves identified to CoIII/CoII and CoII/CoI for [CoIII 2L] were observed at -0.19 V and -0.69 V vs Ag/AgCl, respectively. These potentials are quite similar to those for the corresponding mononuclear complex. An electrogenerated [Co1 2L] species reacts with methyl p-toluenesulfonate to give an organocobalt complex. Two-electron reduction of the dinuclear organocobalt compound yields an unstable intermediate that undergoes rapid decomposition by cleavage of the cobalt-carbon bond. The dimethylated complex, which has cobalt-carbon bonds at one axial site of each cobalt, was disproportionated to a tetramethylated complex, involving two cobalt-carbon bonds at both axial sites, and a dicobalt(I) species by two-electron reduction. The tetramethylated cobalt complex was inactive for an electrochemical reduction, but transformed into the dimethylated complex via cleavage of the cobalt-carbon bonds upon electrochemical oxidation.

AB - New dicobalt complexes, [CoIII 2LBr4], with monoanionic ligands (L) have been synthesized by the reaction of a tetraamine and oximes, followed by an aerobic reaction with CoBr2·6H2O. The complexes were characterized by elemental analyses, IR, ESR, and NMR as well as mass spectroscopies. The redox behavior of the complexes was examined in DMF by means of cyclic voltammetry in comparison with that of the corresponding mononuclear complex. Redox waves identified to CoIII/CoII and CoII/CoI for [CoIII 2L] were observed at -0.19 V and -0.69 V vs Ag/AgCl, respectively. These potentials are quite similar to those for the corresponding mononuclear complex. An electrogenerated [Co1 2L] species reacts with methyl p-toluenesulfonate to give an organocobalt complex. Two-electron reduction of the dinuclear organocobalt compound yields an unstable intermediate that undergoes rapid decomposition by cleavage of the cobalt-carbon bond. The dimethylated complex, which has cobalt-carbon bonds at one axial site of each cobalt, was disproportionated to a tetramethylated complex, involving two cobalt-carbon bonds at both axial sites, and a dicobalt(I) species by two-electron reduction. The tetramethylated cobalt complex was inactive for an electrochemical reduction, but transformed into the dimethylated complex via cleavage of the cobalt-carbon bonds upon electrochemical oxidation.

UR - http://www.scopus.com/inward/record.url?scp=0036320171&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036320171&partnerID=8YFLogxK

U2 - 10.1246/bcsj.75.1553

DO - 10.1246/bcsj.75.1553

M3 - Article

VL - 75

SP - 1553

EP - 1558

JO - Bulletin of the Chemical Society of Japan

JF - Bulletin of the Chemical Society of Japan

SN - 0009-2673

IS - 7

ER -