Synthesis and reactivity of tripodal complexes containing pendant bases

Johanna M. Blacquiere, Michael L. Pegis, Simone Raugei, Werner Kaminsky, Amélie Forget, Sarah A. Cook, Taketo Taguchi, James M. Mayer

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The synthesis of a new tripodal ligand family that contains tertiary amine groups in the second-coordination sphere is reported. The ligands are tris(amido)amine derivatives, with the pendant amines attached via a peptide coupling strategy. They were designed to function as new molecular catalysts for the oxygen reduction reaction (ORR), in which the pendant acid/base group could improve the catalyst performance. Two members of the ligand family were each metalated with cobalt(II) and zinc(II) to afford trigonal-monopyramidal complexes. The reaction of the cobalt complexes [Co(L)]- with dioxygen reversibly generates a small amount of a cobalt(III) superoxo species, which was characterized by electron paramagnetic resonance (EPR) spectroscopy. Protonation of the zinc complex Zn[N{CH2CH2NC(O)CH 2N(CH2Ph)2}3)]- ([Zn(TNBn)]-) with 1 equiv of acid occurs at a primary-coordination-sphere amide moiety rather than at a pendant basic site. The addition of excess acid to any of the complexes [M(L)]- results in complete proteolysis and formation of the ligands H3L. These undesired reactions limit the use of these complexes as catalysts for the ORR. An alternative ligand with two pyridyl arms was also prepared but could not be metalated. These studies highlight the importance of the stability of the primary-coordination sphere of ORR electrocatalysts to both oxidative and acidic conditions.

Original languageEnglish
Pages (from-to)9242-9253
Number of pages12
JournalInorganic Chemistry
Volume53
Issue number17
DOIs
Publication statusPublished - Sep 2 2014

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reactivity
Ligands
Cobalt
ligands
Oxygen
Amines
synthesis
amines
cobalt
catalysts
acids
Catalysts
Acids
Zinc
oxygen
zinc
Proteolysis
electrocatalysts
Electrocatalysts
Protonation

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

Blacquiere, J. M., Pegis, M. L., Raugei, S., Kaminsky, W., Forget, A., Cook, S. A., ... Mayer, J. M. (2014). Synthesis and reactivity of tripodal complexes containing pendant bases. Inorganic Chemistry, 53(17), 9242-9253. https://doi.org/10.1021/ic5013389

Synthesis and reactivity of tripodal complexes containing pendant bases. / Blacquiere, Johanna M.; Pegis, Michael L.; Raugei, Simone; Kaminsky, Werner; Forget, Amélie; Cook, Sarah A.; Taguchi, Taketo; Mayer, James M.

In: Inorganic Chemistry, Vol. 53, No. 17, 02.09.2014, p. 9242-9253.

Research output: Contribution to journalArticle

Blacquiere, JM, Pegis, ML, Raugei, S, Kaminsky, W, Forget, A, Cook, SA, Taguchi, T & Mayer, JM 2014, 'Synthesis and reactivity of tripodal complexes containing pendant bases', Inorganic Chemistry, vol. 53, no. 17, pp. 9242-9253. https://doi.org/10.1021/ic5013389
Blacquiere JM, Pegis ML, Raugei S, Kaminsky W, Forget A, Cook SA et al. Synthesis and reactivity of tripodal complexes containing pendant bases. Inorganic Chemistry. 2014 Sep 2;53(17):9242-9253. https://doi.org/10.1021/ic5013389
Blacquiere, Johanna M. ; Pegis, Michael L. ; Raugei, Simone ; Kaminsky, Werner ; Forget, Amélie ; Cook, Sarah A. ; Taguchi, Taketo ; Mayer, James M. / Synthesis and reactivity of tripodal complexes containing pendant bases. In: Inorganic Chemistry. 2014 ; Vol. 53, No. 17. pp. 9242-9253.
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