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Interactions between the trianionic ligand-centred redox-active metalloligand [CrIII(perfluorocatecholato)3]3− and guest metal ions.
- Source :
- Dalton Transactions: An International Journal of Inorganic Chemistry; 8/28/2015, Vol. 44 Issue 32, p14304-14314, 11p
- Publication Year :
- 2015
-
Abstract
- The redox-active metalloligand (RML) (Et<subscript>3</subscript>NH)<subscript>3</subscript>[Cr<superscript>III</superscript>(F<subscript>4</subscript>Cat)<subscript>3</subscript>] (F<subscript>4</subscript>Cat = perfluorocatecholato) (1) was synthesized and its interactions with guest metal ions Li<superscript>+</superscript>, Mn<superscript>2+</superscript>, Fe<superscript>2+</superscript>, Co<superscript>2+</superscript>, Cu<superscript>2+</superscript>, and Zn<superscript>2+</superscript> were examined. Cyclic voltammetry measurements and spectroelectrochemical studies revealed that complex 1 shows three-step ligand-centred one-electron oxidation to consecutively generate [Cr<superscript>III</superscript>(F<subscript>4</subscript>Cat)<subscript>2</subscript>(F<subscript>4</subscript>SQ)]<superscript>2−</superscript> (F<subscript>4</subscript>SQ = perfluorosemiquinonato), [Cr<superscript>III</superscript>(F<subscript>4</subscript>Cat)(F<subscript>4</subscript>SQ)<subscript>2</subscript>]<superscript>−</superscript>, and [Cr<superscript>III</superscript>(F<subscript>4</subscript>SQ)<subscript>3</subscript>] at −0.12, 0.23, and 0.53 V vs. Ag/Ag<superscript>+</superscript> in dichloromethane, or at −0.21, 0.08, and 0.50 V in acetonitrile (MeCN), respectively. Titration experiments in MeCN revealed that treatment of 1 with Cu<superscript>2+</superscript> leads to the formation of [Cr<superscript>III</superscript>(F<subscript>4</subscript>Cat)<subscript>2</subscript>(F<subscript>4</subscript>SQ)]<superscript>2−</superscript> and Cu<superscript>+</superscript>via a redox reaction. However, when 1 was treated with Li<superscript>+</superscript>, Mn<superscript>2+</superscript>, Fe<superscript>2+</superscript>, Co<superscript>2+</superscript>, and Zn<superscript>2+</superscript>, further titration experiments revealed that these metal ions coordinated via the lone pairs on the coordinating oxygen atoms of the F<subscript>4</subscript>Cat<superscript>2−</superscript> moieties in a one-to-one ratio, and binding constants of 3.7 (±0.3) × 10<superscript>4</superscript> (Li<superscript>+</superscript>), 1.5 (±0.2) × 10<superscript>5</superscript> (Mn<superscript>2+</superscript>), 2.2 (±0.4) × 10<superscript>5</superscript> (Fe<superscript>2+</superscript>), 1.9 (±0.2) × 10<superscript>5</superscript> (Co<superscript>2+</superscript>), and 3.8 (±0.4) × 10<superscript>5</superscript> M<superscript>−1</superscript> (Zn<superscript>2+</superscript>) were established. Moreover, the oxidation potentials of 1 were positively shifted by 0.08–0.33 V upon addition of guest metal ions. Spectroelectrochemical studies of 1 in the presence of guest metal ions suggested that ligand-centred one- and two-electron oxidation of the RML occurred for Li<superscript>+</superscript>, Mn<superscript>2+</superscript>, Co<superscript>2+</superscript>, and Zn<superscript>2+</superscript>, respectively, while guest metal-centred one-electron oxidation was observed for Fe<superscript>2+</superscript>. Considering all the aforementioned results, this study demonstrated for the first time the ability of [Cr<superscript>III</superscript>(F<subscript>4</subscript>Cat)<subscript>3</subscript>]<superscript>3−</superscript> to act as a RML in solution. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14779226
- Volume :
- 44
- Issue :
- 32
- Database :
- Complementary Index
- Journal :
- Dalton Transactions: An International Journal of Inorganic Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 108725233
- Full Text :
- https://doi.org/10.1039/c5dt01963j