title: Phenolate and phenoxyl radical complexes of Co(II) and Co(III).
abstract: The new phenol-imidazole pro-ligands (R)LH react with Co(BF(4))(2).6H(2)O in the presence of Et(3)N to form the corresponding [Co(II)((R)L)(2)] compound (R = Ph (1), PhOMe (2), or Bz (3)). Also, (Bz)LH, reacts with Co(ii) in the presence of Et(3)N and H(2)O(2) to form [Co(III)((Bz)L)(3)](4). The structures of 1.2.5MeCN, 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-N(3)O(3) distorted octahedral geometry. [Co(II)((R)L)(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)((R)L*)((R)L)(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](+), [Co(III)((Bz)L*)((Bz)L)(2)](+). Unlike [1](+) and [2](+), product of the one-electron oxidation of [Co(II)((Bz)L)(2)], [3](+), is unstable and decomposes to produce [4](+). These studies have demonstrated that the chemical properties of [M(II)((R)L*)((R)L)(2)](+)(M = Co, Cu, Zn) are highly dependent on the nature of both the ligand and the metal centre.
authors.affiliation: School of Chemistry, The University of Nottingham, University Park, Nottingham, UK NG7 2RD.
authors.forename: Laurent
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authors.lastname: Benisvy
authors.forename: Eckhard
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authors.lastname: Bill
authors.forename: Alexander J
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authors.lastname: Collison
authors.forename: E Stephen
authors.initials: ES
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authors.forename: C David
authors.initials: CD
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authors.forename: Christina I
authors.initials: CI
authors.lastname: Guindy
authors.forename: Eric J L
authors.initials: EJ
authors.lastname: McInnes
authors.forename: Graeme
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authors.lastname: McArdle
authors.forename: Jonathan
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authors.lastname: McMaster
authors.forename: Claire
authors.initials: C
authors.lastname: Wilson
authors.forename: Joanna
authors.initials: J
authors.lastname: Wolowska