Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode Processes

Dinuclear di-<i>µ</i>-oxo complexes of Mn<sup>3+</sup> and Mn<sup>4+</sup> ions, and mononuclear complexes of Mn<sup>3+</sup> ions with tetraazamacrocycles ([12]aneN<sub>4</sub>, [14]aneN<sub>4</sub>, [15]aneN<sub>4</su...

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Main Authors: Danuta Tomczyk, Sławomira Skrzypek, Piotr Seliger
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/8/1860
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author Danuta Tomczyk
Sławomira Skrzypek
Piotr Seliger
author_facet Danuta Tomczyk
Sławomira Skrzypek
Piotr Seliger
author_sort Danuta Tomczyk
collection DOAJ
description Dinuclear di-<i>µ</i>-oxo complexes of Mn<sup>3+</sup> and Mn<sup>4+</sup> ions, and mononuclear complexes of Mn<sup>3+</sup> ions with tetraazamacrocycles ([12]aneN<sub>4</sub>, [14]aneN<sub>4</sub>, [15]aneN<sub>4</sub>) and <i>C</i>-substituted derivative (Me<sub>6</sub>[14]aneN<sub>4</sub>) as well as mononuclear complexes of Mn<sup>2+</sup> ions with <i>N</i>-substituted derivatives ((<i>N</i>-Me)<sub>2</sub>[14]aneN<sub>4</sub>, (<i>N</i>-Me)<sub>4</sub>[14]aneN<sub>4</sub>, (<i>N</i>-Me)Me<sub>2</sub>py [14]aneN<sub>4</sub>) and with oxo<sub>2</sub>[14]aneN<sub>4</sub> were studied. Based on spectroscopic (UV VIS and IR) and conductometric studies, the types of synthesised complexes (<i>cis</i> or <i>trans</i> isomers of mononuclear Mn<sup>3+</sup> complexes, oxygen bridges and class II according to Robin and Day classification for dinuclear complexes) were determined. On the basis of voltammetric and spectroelectrochemical studies, <i>trans-cis</i> isomerisation at the level of Mn<sup>2+</sup> ion complexes and <i>cis-trans</i> isomerisation at the level of Mn<sup>3+</sup> ion complexes were demonstrated for complexes of ligands with free C positions. The <i>N</i>-substituted derivatives oxidise according to the EC mechanism, in which the follow-up reaction is a disproportionation reaction. The thermodynamic stabilisation of Mn<sup>3+</sup> ions was determined by comparing the formal potentials (<i>E<sub>f</sub></i><sup>0</sup>), the disproportionation constants (<i>k</i><sub>1</sub>) and the formation constants (<i>β<sup>III</sup></i>). The study showed the possibility of oxidation of mononuclear, pseudo-octahedral Mn<sup>3+</sup> ion complexes to dinuclear complexes and the greatest stabilisation of Mn<sup>3+</sup> ions, both in monomers and dimers of ligands with free <i>N</i> positions.
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spelling doaj-art-87ea4a90a1514bf09b191d46dc8452e32025-08-20T03:13:58ZengMDPI AGMolecules1420-30492025-04-01308186010.3390/molecules30081860Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode ProcessesDanuta Tomczyk0Sławomira Skrzypek1Piotr Seliger2University of Lodz, Faculty of Chemistry, Department of Inorganic and Analytical Chemistry, Tamka 12, 91-403 Lodz, PolandUniversity of Lodz, Faculty of Chemistry, Department of Inorganic and Analytical Chemistry, Tamka 12, 91-403 Lodz, PolandUniversity of Lodz, Faculty of Chemistry, Department of Inorganic and Analytical Chemistry, Tamka 12, 91-403 Lodz, PolandDinuclear di-<i>µ</i>-oxo complexes of Mn<sup>3+</sup> and Mn<sup>4+</sup> ions, and mononuclear complexes of Mn<sup>3+</sup> ions with tetraazamacrocycles ([12]aneN<sub>4</sub>, [14]aneN<sub>4</sub>, [15]aneN<sub>4</sub>) and <i>C</i>-substituted derivative (Me<sub>6</sub>[14]aneN<sub>4</sub>) as well as mononuclear complexes of Mn<sup>2+</sup> ions with <i>N</i>-substituted derivatives ((<i>N</i>-Me)<sub>2</sub>[14]aneN<sub>4</sub>, (<i>N</i>-Me)<sub>4</sub>[14]aneN<sub>4</sub>, (<i>N</i>-Me)Me<sub>2</sub>py [14]aneN<sub>4</sub>) and with oxo<sub>2</sub>[14]aneN<sub>4</sub> were studied. Based on spectroscopic (UV VIS and IR) and conductometric studies, the types of synthesised complexes (<i>cis</i> or <i>trans</i> isomers of mononuclear Mn<sup>3+</sup> complexes, oxygen bridges and class II according to Robin and Day classification for dinuclear complexes) were determined. On the basis of voltammetric and spectroelectrochemical studies, <i>trans-cis</i> isomerisation at the level of Mn<sup>2+</sup> ion complexes and <i>cis-trans</i> isomerisation at the level of Mn<sup>3+</sup> ion complexes were demonstrated for complexes of ligands with free C positions. The <i>N</i>-substituted derivatives oxidise according to the EC mechanism, in which the follow-up reaction is a disproportionation reaction. The thermodynamic stabilisation of Mn<sup>3+</sup> ions was determined by comparing the formal potentials (<i>E<sub>f</sub></i><sup>0</sup>), the disproportionation constants (<i>k</i><sub>1</sub>) and the formation constants (<i>β<sup>III</sup></i>). The study showed the possibility of oxidation of mononuclear, pseudo-octahedral Mn<sup>3+</sup> ion complexes to dinuclear complexes and the greatest stabilisation of Mn<sup>3+</sup> ions, both in monomers and dimers of ligands with free <i>N</i> positions.https://www.mdpi.com/1420-3049/30/8/1860manganese dinuclear complexcyclamcyclentetraazamacrocycledisproportionation constant
spellingShingle Danuta Tomczyk
Sławomira Skrzypek
Piotr Seliger
Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode Processes
Molecules
manganese dinuclear complex
cyclam
cyclen
tetraazamacrocycle
disproportionation constant
title Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode Processes
title_full Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode Processes
title_fullStr Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode Processes
title_full_unstemmed Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode Processes
title_short Influence of the Type of Macrocycle on the Stabilisation of the High Oxidation State of the Manganese Ion and Electrode Processes
title_sort influence of the type of macrocycle on the stabilisation of the high oxidation state of the manganese ion and electrode processes
topic manganese dinuclear complex
cyclam
cyclen
tetraazamacrocycle
disproportionation constant
url https://www.mdpi.com/1420-3049/30/8/1860
work_keys_str_mv AT danutatomczyk influenceofthetypeofmacrocycleonthestabilisationofthehighoxidationstateofthemanganeseionandelectrodeprocesses
AT sławomiraskrzypek influenceofthetypeofmacrocycleonthestabilisationofthehighoxidationstateofthemanganeseionandelectrodeprocesses
AT piotrseliger influenceofthetypeofmacrocycleonthestabilisationofthehighoxidationstateofthemanganeseionandelectrodeprocesses