Spectroscopy and Electrochemistry of Cobalt(III) Schiff Base Complexes

Arnd Böttcher, Toshihiko Takeuchi, Kenneth I. Hardcastle, Thomas J. Meade, Harry B. Gray*, Dory Cwikel, Moshe Kapon, Zvi Dori

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

247 Scopus citations

Abstract

The structural, spectroscopic, and electrochemical properties of cobalt(III) derivatives of acacen (H2acacen = bis(acetylacetone) ethylenediimine) and related ligands have been investigated. Electronic structure calculations indicate that the absorption between 340 and 378 nm in CoIII(acacen) spectra is attributable to the lowest π-π* intraligand charge-transfer transition. Equatorial ligand substitutions affect reduction potentials less than axial ligand changes, consistent with an electronic structural model in which dZ2 is populated in forming cobalt(II). The crystal structure of [Co(3-Cl-acacen)(NH3)2]BPh4 has been determined: The compound crystallizes in the monoclinic space group P21/m (No. 11) with a = 9.720(2) Å, b = 18.142(4) Å, c = 10.046(2) Å, β= 100.11(3)°, Dc = 1.339 g cm-3, and Z = 2; the complex cation, [Co(3-Cl-acacen)(NH3)2]+, exhibits a slightly distorted octahedral coordination geometry. The distances between the cobalt atom and the two axial nitrogen donor atoms differ only slightly (1.960(6) and 1.951 (6) Å) and are similar to Co-N distances found in cobalt-arnmine complexes as well as the axial Co-N distances in [Co(acacen)(4-MeIm)2]Br·1.5H2O; the latter compound crystallizes in the triclinic space group P1̄ (No. 2) with a = 18.466(9) Å, b= 14.936(7) Å, c = 10.111(5)Å, α = 96.27(5)°, β = 94.12(5)°, γ = 112.78(5)°, Dc = 1.447 g cm-3, and Z = 4.

Original languageEnglish (US)
Pages (from-to)2498-2504
Number of pages7
JournalInorganic chemistry
Volume36
Issue number12
DOIs
StatePublished - Jan 1 1997

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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