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Issue 7, 2003
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H3O2, O22− and O2˙ bridging ligands in cobalt(iii) complexes of an acyclic phenolate-hinged dinucleating ligand

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Abstract

The dicobalt(III) complex, [Co2(bpbp)(μ-H3O2)2](ClO4)3 (bpbp = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-tert-butylphenolate), obtained by reaction of cobalt(II) perchlorate with Hbpbp under ambient conditions contains two μ-H3O2 bridging ligands. The H-bonded O⋯O distances in this motif are 2.437(3) and 2.456(4) Å, respectively, with a Co⋯Co separation of 3.601(1) Å. The structurally precedented peroxo bridged complexes, [Co2(bpbp)(μ-O2)(μ-RCO2)](ClO4)2 (R = CH3 or C6H5), are formed if a carboxylate is present. The X-ray crystal structure showed O–O and Co⋯Co distances of 1.422(3) and 3.168(1) Å, respectively, in the case of R = CH3. ESI-MS shows that the bridging peroxo ligand is easily eliminated from [Co2(bpbp)(μ-O2)(μ-CH3CO2)]2+, m/z 390.0, as implicated by the observation of [Co2(bpbp)(μ-CH3CO2)]2+, m/z 374.1, corresponding to loss of the mass equivalent of dioxygen. The superoxo complex [Co2(bpbp)(μ-O2)(μ-CH3CO2)]3+ can be prepared by Ce(IV) oxidation of [Co2(bpbp)(μ-O2)(μ-CH3CO2)]2+. Reaction of [Co2(bpbp)(μ-H3O2)2]3+ with hydrazine in air gives the dicobalt(II) complex [Co2(bpbp)(NH2NHCO2)2]ClO4. In this complex the two exogenous hydrazinecarboxylato ligands are bound to individual metal ions with weak H-bonding between them as shown by X-ray structure analysis.

Graphical abstract: H3O2−, O22− and O2˙− bridging ligands in cobalt(iii) complexes of an acyclic phenolate-hinged dinucleating ligand

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Publication details

The article was received on 14 Oct 2002, accepted on 14 Feb 2003 and first published on 03 Mar 2003


Article type: Paper
DOI: 10.1039/B210091F
Dalton Trans., 2003, 1320-1325

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    H3O2, O22− and O2˙ bridging ligands in cobalt(III) complexes of an acyclic phenolate-hinged dinucleating ligand

    M. Ghiladi, J. T. Gomez, A. Hazell, P. Kofod, J. Lumtscher and C. J. McKenzie, Dalton Trans., 2003, 1320
    DOI: 10.1039/B210091F

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