Diphenoxo-bridged NiCo and CuCo complexes of macrocyclic ligands: Synthesis, structure and electrochemical behaviour

Takanori Aono, Hisae Wada, Masami Yonemura, Hideki Furutachi, Masaaki Ohba, Hisashi Okawa

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22 Citations (Scopus)

Abstract

Heterodinuclear di-μ-phenoxo-MIICoII (M = Ni or Cu) complexes have been derived from phenol-based dinucleating ligands (Lm,n)2-, comprising of two 2,6-di(iminomethyl)-4-methylphenolate entities linked by two lateral chains (CH2)m (m = 2 or 3) and (CH2)n (n = 3 or 4) at the imino nitrogens. The crystal structure of [CuCo(L2,3)(dmf)2(H2O)][ClO4] 2 (dmf = dimethylformarmide) has been determined. The copper ion resides at the N2O2 site formed by the ethylene lateral chain and assumes a square-pyramidal geometry together with a dmf oxygen at the apex. The Co at the site of the trimethylene lateral chain assumes a pseudo-octahedral geometry together with a dmf and a water molecule at the axial positions. The Cu ⋯ Co separation doubly bridged by the phenolic oxygens is 2.998(2) Å. The NiCo complexes are paramagnetic (SNI = 0), whereas the CuCo complexes show a strong antiferromagnetic interaction between the two metal ions. Cyclic voltammograms of the NiCo complexes show two quasi-reversible couples attributable to the stepwise reductions: NiIICoII → NiICoII → NiICoI. The NiICoI and NiICoI complexes were prepared in solution by coulometry and characterized by visible spectroscopy. Similarly, the CuCo complex of (L3,3)2- is reduced stepwise to CuICoII and then to CuICoI. On the other hand, the CuCo complexes of (L2,3)2- and (L2,4)2- showed unusual electrochemical behaviour at the electrode suggesting a scrambling or site exchange of the metal ions.

Original languageEnglish
Pages (from-to)3029-3034
Number of pages6
JournalJournal of the Chemical Society - Dalton Transactions
Issue number17
DOIs
Publication statusPublished - Sep 7 1997

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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