Redox Interconversion between Cobalt(III) Thiolate and Cobalt(II) Disulfide Compounds

Feng Jiang; Maxime A. Siegler; Xiaobo Sun; Lin Jiang; Célia Fonseca Guerra; Elisabeth Bouwman

doi:10.1021/acs.inorgchem.8b00549

Redox Interconversion between Cobalt(III) Thiolate and Cobalt(II) Disulfide Compounds

Feng Jiang, Maxime A. Siegler, Xiaobo Sun, Lin Jiang, Célia Fonseca Guerra^*, Elisabeth Bouwman

^*Corresponding author for this work

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Abstract

The redox interconversion between Co(III) thiolate and Co(II) disulfide compounds has been investigated experimentally and computationally. Reactions of cobalt(II) salts with disulfide ligand L¹SSL¹ (L¹SSL¹ = di-2-(bis(2-pyridylmethyl)amino)-ethyl disulfide) result in the formation of either the high-spin cobalt(II) disulfide compound [Co^II ₂(L¹SSL¹)Cl₄] or a low-spin, octahedral cobalt(III) thiolate compound, such as [Co^III(L¹S)(MeCN)₂](BF₄)₂. Addition of thiocyanate anions to a solution containing the latter compound yielded crystals of [Co^III(L¹S)(NCS)₂]. The addition of chloride ions to a solution of [Co^III(L¹S)(MeCN)₂](BF₄)₂ in acetonitrile results in conversion of the cobalt(III) thiolate compound to the cobalt(II) disulfide compound [Co^II ₂(L¹SSL¹)Cl₄], as monitored with UV-vis spectroscopy; subsequent addition of AgBF₄ regenerates the Co(III) compound. Computational studies show that exchange by a chloride anion of the coordinated acetonitrile molecule or thiocyanate anion in compounds [Co^III(L¹S)(MeCN)₂]²⁺ and [Co^III(L¹S)(NCS)₂] induces a change in the character of the highest occupied molecular orbitals, showing a decrease of the contribution of the p orbital on sulfur and an increase of the d orbital on cobalt. As a comparison, the synthesis of iron compounds was undertaken. X-ray crystallography revealed that structure of the dinuclear iron(II) disulfide compound [Fe^II ₂(L¹SSL¹)Cl₄] is different from that of cobalt(II) compound [Co^II ₂(L¹SSL¹)Cl₄]. In contrast to cobalt, reaction of ligand L¹SSL¹ with [Fe(MeCN)₆](BF₄)₂ did not yield the expected Fe(III) thiolate compound. This work is an unprecedented example of redox interconversion between a high-spin Co(II) disulfide compound and a low-spin Co(III) thiolate compound triggered by the nature of the anion.

Original language	English
Pages (from-to)	8796-8805
Number of pages	10
Journal	Inorganic Chemistry
Volume	57
Issue number	15
Early online date	19 Jul 2018
DOIs	https://doi.org/10.1021/acs.inorgchem.8b00549
Publication status	Published - 6 Aug 2018

Funding

F.J. and L.J. gratefully acknowledge the China Scholarship Council (CSC) for a personal grant (Nos. 201406890012 and 201406890016). The Netherlands Organization for Scientific Research (NWO−CW) is acknowledged for the financial support. We thank Mr. Anne Geert Volbeda, Jos van Brussel and Wim Jesse for ESI-MS analysis, Mr. Fons Lefeber for assistance with the NMR spectrometers. Dr. G. F. Schneider is acknowledged for use of the Raman spectrometer.

Funders	Funder number
Netherlands Organization for Scientific Research
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
China Scholarship Council	201406890012, 201406890016

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@article{b951e4732b7b4c1a8acca2776ba94b2f,

title = "Redox Interconversion between Cobalt(III) Thiolate and Cobalt(II) Disulfide Compounds",

abstract = "The redox interconversion between Co(III) thiolate and Co(II) disulfide compounds has been investigated experimentally and computationally. Reactions of cobalt(II) salts with disulfide ligand L1SSL1 (L1SSL1 = di-2-(bis(2-pyridylmethyl)amino)-ethyl disulfide) result in the formation of either the high-spin cobalt(II) disulfide compound [CoII 2(L1SSL1)Cl4] or a low-spin, octahedral cobalt(III) thiolate compound, such as [CoIII(L1S)(MeCN)2](BF4)2. Addition of thiocyanate anions to a solution containing the latter compound yielded crystals of [CoIII(L1S)(NCS)2]. The addition of chloride ions to a solution of [CoIII(L1S)(MeCN)2](BF4)2 in acetonitrile results in conversion of the cobalt(III) thiolate compound to the cobalt(II) disulfide compound [CoII 2(L1SSL1)Cl4], as monitored with UV-vis spectroscopy; subsequent addition of AgBF4 regenerates the Co(III) compound. Computational studies show that exchange by a chloride anion of the coordinated acetonitrile molecule or thiocyanate anion in compounds [CoIII(L1S)(MeCN)2]2+ and [CoIII(L1S)(NCS)2] induces a change in the character of the highest occupied molecular orbitals, showing a decrease of the contribution of the p orbital on sulfur and an increase of the d orbital on cobalt. As a comparison, the synthesis of iron compounds was undertaken. X-ray crystallography revealed that structure of the dinuclear iron(II) disulfide compound [FeII 2(L1SSL1)Cl4] is different from that of cobalt(II) compound [CoII 2(L1SSL1)Cl4]. In contrast to cobalt, reaction of ligand L1SSL1 with [Fe(MeCN)6](BF4)2 did not yield the expected Fe(III) thiolate compound. This work is an unprecedented example of redox interconversion between a high-spin Co(II) disulfide compound and a low-spin Co(III) thiolate compound triggered by the nature of the anion.",

author = "Feng Jiang and Siegler, {Maxime A.} and Xiaobo Sun and Lin Jiang and {Fonseca Guerra}, C{\'e}lia and Elisabeth Bouwman",

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T1 - Redox Interconversion between Cobalt(III) Thiolate and Cobalt(II) Disulfide Compounds

AU - Jiang, Feng

AU - Siegler, Maxime A.

AU - Sun, Xiaobo

AU - Jiang, Lin

AU - Fonseca Guerra, Célia

AU - Bouwman, Elisabeth

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N2 - The redox interconversion between Co(III) thiolate and Co(II) disulfide compounds has been investigated experimentally and computationally. Reactions of cobalt(II) salts with disulfide ligand L1SSL1 (L1SSL1 = di-2-(bis(2-pyridylmethyl)amino)-ethyl disulfide) result in the formation of either the high-spin cobalt(II) disulfide compound [CoII 2(L1SSL1)Cl4] or a low-spin, octahedral cobalt(III) thiolate compound, such as [CoIII(L1S)(MeCN)2](BF4)2. Addition of thiocyanate anions to a solution containing the latter compound yielded crystals of [CoIII(L1S)(NCS)2]. The addition of chloride ions to a solution of [CoIII(L1S)(MeCN)2](BF4)2 in acetonitrile results in conversion of the cobalt(III) thiolate compound to the cobalt(II) disulfide compound [CoII 2(L1SSL1)Cl4], as monitored with UV-vis spectroscopy; subsequent addition of AgBF4 regenerates the Co(III) compound. Computational studies show that exchange by a chloride anion of the coordinated acetonitrile molecule or thiocyanate anion in compounds [CoIII(L1S)(MeCN)2]2+ and [CoIII(L1S)(NCS)2] induces a change in the character of the highest occupied molecular orbitals, showing a decrease of the contribution of the p orbital on sulfur and an increase of the d orbital on cobalt. As a comparison, the synthesis of iron compounds was undertaken. X-ray crystallography revealed that structure of the dinuclear iron(II) disulfide compound [FeII 2(L1SSL1)Cl4] is different from that of cobalt(II) compound [CoII 2(L1SSL1)Cl4]. In contrast to cobalt, reaction of ligand L1SSL1 with [Fe(MeCN)6](BF4)2 did not yield the expected Fe(III) thiolate compound. This work is an unprecedented example of redox interconversion between a high-spin Co(II) disulfide compound and a low-spin Co(III) thiolate compound triggered by the nature of the anion.

AB - The redox interconversion between Co(III) thiolate and Co(II) disulfide compounds has been investigated experimentally and computationally. Reactions of cobalt(II) salts with disulfide ligand L1SSL1 (L1SSL1 = di-2-(bis(2-pyridylmethyl)amino)-ethyl disulfide) result in the formation of either the high-spin cobalt(II) disulfide compound [CoII 2(L1SSL1)Cl4] or a low-spin, octahedral cobalt(III) thiolate compound, such as [CoIII(L1S)(MeCN)2](BF4)2. Addition of thiocyanate anions to a solution containing the latter compound yielded crystals of [CoIII(L1S)(NCS)2]. The addition of chloride ions to a solution of [CoIII(L1S)(MeCN)2](BF4)2 in acetonitrile results in conversion of the cobalt(III) thiolate compound to the cobalt(II) disulfide compound [CoII 2(L1SSL1)Cl4], as monitored with UV-vis spectroscopy; subsequent addition of AgBF4 regenerates the Co(III) compound. Computational studies show that exchange by a chloride anion of the coordinated acetonitrile molecule or thiocyanate anion in compounds [CoIII(L1S)(MeCN)2]2+ and [CoIII(L1S)(NCS)2] induces a change in the character of the highest occupied molecular orbitals, showing a decrease of the contribution of the p orbital on sulfur and an increase of the d orbital on cobalt. As a comparison, the synthesis of iron compounds was undertaken. X-ray crystallography revealed that structure of the dinuclear iron(II) disulfide compound [FeII 2(L1SSL1)Cl4] is different from that of cobalt(II) compound [CoII 2(L1SSL1)Cl4]. In contrast to cobalt, reaction of ligand L1SSL1 with [Fe(MeCN)6](BF4)2 did not yield the expected Fe(III) thiolate compound. This work is an unprecedented example of redox interconversion between a high-spin Co(II) disulfide compound and a low-spin Co(III) thiolate compound triggered by the nature of the anion.

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ER -

Redox Interconversion between Cobalt(III) Thiolate and Cobalt(II) Disulfide Compounds

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CCDC 1496381: Experimental Crystal Structure Determination

CCDC 1827153: Experimental Crystal Structure Determination

CCDC 1496385: Experimental Crystal Structure Determination

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Redox Interconversion between Cobalt(III) Thiolate and Cobalt(II) Disulfide Compounds

Abstract

Funding

UN SDGs

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Datasets

CCDC 1496381: Experimental Crystal Structure Determination

CCDC 1827153: Experimental Crystal Structure Determination

CCDC 1496385: Experimental Crystal Structure Determination

Cite this