Phenolate and phenoxyl radical complexes of Co(II) and Co(III)

Laurent Benisvy*, Eckhard Bill, Alexander J. Blake, David Collison, E. Stephen Davies, C. David Garner, Christina Irene Guindy, Eric J.L. McInnes, Graeme McArdle, Jonathan McMaster, Claire Wilson, Joanna Wolowska

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


The new phenol-imidazole pro-ligands RLH react with Co(BF 4)2·6H2O in the presence of Et 3N to form the corresponding [CoII(RL) 2] compound (R = Ph (1), PhOMe (2), or Bz (3)). Also, BzLH, reacts with Co(II) in the presence of Et3N and H2O2 to form [CoIII(BzL) 3] (4). The structures of l·2.5MeCN, 2·2DMF, 3·4MeOH, and 4·4DMF have been determined by X-ray crystallography. 1, 2, and 3 each involve Co(II) bound to two N,O-bidentate ligands with a distorted tetrahedral coordination sphere; 4 involves Co(III) bound to three N,O-bidentate ligands in a mer-N3O3 distorted octahedral geometry. [CoII(RL)2] (R = Ph or PhOMe) undergo two, one-electron, oxidations. The products of the first oxidation, [1] + and [2]+, have been synthesised by the chemical oxidation of 1 and 2, respectively; these cations, formulated as [Co II(RL)(RL)2]+, comprise one phenoxyl radical and one phenolate ligand bound to Co(II) and are the first phenoxyl radical ligand complexes of tetra-coordinated Co(II). 4 undergoes two, one-electron, ligand-based oxidations, the first of which produces [4] +, [CoIII(BzL)(BzL)2]+. Unlike [l]+and [2]+, product of the one-electron oxidation of [CoII(BzL)2], [3]+, is unstable and decomposes to produce [4]+. These studies have demonstrated that the chemical properties of [MII(RL)(RL) 2]+ (M = Co, Cu, Zn) are highly dependent on the nature of both the ligand and the metal centre.

Original languageEnglish (US)
Pages (from-to)3647-3653
Number of pages7
JournalDalton Transactions
Issue number21
StatePublished - Nov 7 2004

ASJC Scopus subject areas

  • Inorganic Chemistry


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