Mixed-valent polynuclear cobalt complexes incorporating tetradentate phenoxyamine ligands

Joo Chuan Ang; Yanyan Mulyana; Chris Ritchie; Rodolphe Cĺrac; Colette Boskovic

doi:10.1071/CH09256

Mixed-valent polynuclear cobalt complexes incorporating tetradentate phenoxyamine ligands

Joo Chuan Ang, Yanyan Mulyana, Chris Ritchie, Rodolphe Cĺrac, Colette Boskovic

Research output: Contribution to journal › Article › Research › peer-review

6 Citations (Scopus)

Abstract

The new potentially tetradentate ligand precursor 2-[(bis(2-hydroxyethyl) amino)methyl]-4,6-bis-tert-butylphenol (H₃L) has been synthesized and characterized. The reaction of H₃L with cobalt(ii) acetate has afforded the novel mixed-valent tetra- and pentanuclear cobalt complexes [Co^II ₂Co^III ₂(OAc) ₂(L)₂(HL)] (1) and [Co^IICo^III ₄(OAc)₂(L)₄] (2). Single-crystal X-ray diffraction studies of these complexes indicate different coordination geometries for the divalent cobalt centres in each complex, with distorted trigonal bipyramidal and distorted tetrahedral coordination evident in 1 and 2, respectively. The variable temperature magnetic susceptibility data for complex 1 reveal behaviour dominated by antiferromagnetic coupling between the two cobalt(ii) centres. Their approximate trigonal bipyramidal coordination geometries give rise to a ⁴A′₂ ground term, allowing a spin-only treatment assuming local spin quantum numbers of S_i = 3/2. Fitting the data to the Heisenberg exchange Hamiltonian (_ex = 2JS₁S₂) results in J = 6.9(1) cm^-1 and g = 2.30(5).

Original language	English
Pages (from-to)	1124-1129
Number of pages	6
Journal	Australian Journal of Chemistry
Volume	62
Issue number	9
DOIs	https://doi.org/10.1071/CH09256
Publication status	Published - 1 Jan 2009
Externally published	Yes

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10.1071/CH09256

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@article{aa4270bc9fc940c8adcedcbce21e41af,

title = "Mixed-valent polynuclear cobalt complexes incorporating tetradentate phenoxyamine ligands",

abstract = "The new potentially tetradentate ligand precursor 2-[(bis(2-hydroxyethyl) amino)methyl]-4,6-bis-tert-butylphenol (H3L) has been synthesized and characterized. The reaction of H3L with cobalt(ii) acetate has afforded the novel mixed-valent tetra- and pentanuclear cobalt complexes [CoII 2CoIII 2(OAc) 2(L)2(HL)] (1) and [CoIICoIII 4(OAc)2(L)4] (2). Single-crystal X-ray diffraction studies of these complexes indicate different coordination geometries for the divalent cobalt centres in each complex, with distorted trigonal bipyramidal and distorted tetrahedral coordination evident in 1 and 2, respectively. The variable temperature magnetic susceptibility data for complex 1 reveal behaviour dominated by antiferromagnetic coupling between the two cobalt(ii) centres. Their approximate trigonal bipyramidal coordination geometries give rise to a 4A′2 ground term, allowing a spin-only treatment assuming local spin quantum numbers of Si = 3/2. Fitting the data to the Heisenberg exchange Hamiltonian (ex = 2JS1S2) results in J = 6.9(1) cm-1 and g = 2.30(5).",

author = "Ang, {Joo Chuan} and Yanyan Mulyana and Chris Ritchie and Rodolphe C{\'l}rac and Colette Boskovic",

year = "2009",

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doi = "10.1071/CH09256",

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T1 - Mixed-valent polynuclear cobalt complexes incorporating tetradentate phenoxyamine ligands

AU - Ang, Joo Chuan

AU - Mulyana, Yanyan

AU - Ritchie, Chris

AU - Cĺrac, Rodolphe

AU - Boskovic, Colette

PY - 2009/1/1

Y1 - 2009/1/1

N2 - The new potentially tetradentate ligand precursor 2-[(bis(2-hydroxyethyl) amino)methyl]-4,6-bis-tert-butylphenol (H3L) has been synthesized and characterized. The reaction of H3L with cobalt(ii) acetate has afforded the novel mixed-valent tetra- and pentanuclear cobalt complexes [CoII 2CoIII 2(OAc) 2(L)2(HL)] (1) and [CoIICoIII 4(OAc)2(L)4] (2). Single-crystal X-ray diffraction studies of these complexes indicate different coordination geometries for the divalent cobalt centres in each complex, with distorted trigonal bipyramidal and distorted tetrahedral coordination evident in 1 and 2, respectively. The variable temperature magnetic susceptibility data for complex 1 reveal behaviour dominated by antiferromagnetic coupling between the two cobalt(ii) centres. Their approximate trigonal bipyramidal coordination geometries give rise to a 4A′2 ground term, allowing a spin-only treatment assuming local spin quantum numbers of Si = 3/2. Fitting the data to the Heisenberg exchange Hamiltonian (ex = 2JS1S2) results in J = 6.9(1) cm-1 and g = 2.30(5).

AB - The new potentially tetradentate ligand precursor 2-[(bis(2-hydroxyethyl) amino)methyl]-4,6-bis-tert-butylphenol (H3L) has been synthesized and characterized. The reaction of H3L with cobalt(ii) acetate has afforded the novel mixed-valent tetra- and pentanuclear cobalt complexes [CoII 2CoIII 2(OAc) 2(L)2(HL)] (1) and [CoIICoIII 4(OAc)2(L)4] (2). Single-crystal X-ray diffraction studies of these complexes indicate different coordination geometries for the divalent cobalt centres in each complex, with distorted trigonal bipyramidal and distorted tetrahedral coordination evident in 1 and 2, respectively. The variable temperature magnetic susceptibility data for complex 1 reveal behaviour dominated by antiferromagnetic coupling between the two cobalt(ii) centres. Their approximate trigonal bipyramidal coordination geometries give rise to a 4A′2 ground term, allowing a spin-only treatment assuming local spin quantum numbers of Si = 3/2. Fitting the data to the Heisenberg exchange Hamiltonian (ex = 2JS1S2) results in J = 6.9(1) cm-1 and g = 2.30(5).

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