Redox Potential - (Electronic) Structure Relationships in 18- and 17-Electron Mononitrile (or Monocarbonyl) Diphosphine Complexes of Re and Fe

[img]PDF - Authorized users only
Language: English
163Kb
Title:Redox Potential - (Electronic) Structure Relationships in 18- and 17-Electron Mononitrile (or Monocarbonyl) Diphosphine Complexes of Re and Fe
Creators:
Guedes Da Silva, M. Fátima C.
Martins, Luísa M. D. R. S.
Fraústo Da Silva, João J. R.
Pombeiro, Armando J. L.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 66, 1, pp. 139-154
Uncontrolled Keywords:Carbonyl complexes, Nitrile complexes, Cyclic voltammetry, Redox potential, Electrochemistry, Iron, Rhenium

Abstract

The organonitrile or carbonyl complexes <i>cis</i>-[ReCl(RCN)(dppe)<sub>2</sub>] (<strong>1</strong>) (R = 4-Et<sub>2</sub>NC<sub>6</sub>H<sub>4</sub> (<strong>1a</strong>), 4-MeOC<sub>6</sub>H<sub>4</sub> (<strong>1b</strong>), 4-MeC<sub>6</sub>H<sub>4</sub> (<strong>1c</strong>), C<sub>6</sub>H<sub>5</sub> (<strong>1d</strong>), 4-FC<sub>6</sub>H<sub>4</sub> (<strong>1e</strong>), 4-ClC<sub>6</sub>H<sub>4</sub> (<strong>1f</strong>), 4-O<sub>2</sub>NC<sub>6</sub>H<sub>4</sub> (<strong>1g</strong>), 4-ClC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub> (<strong>1h</strong>), <i>t</i>-Bu (<strong>1i</strong>); dppe = Ph<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>), or <i>cis</i>-[ReCl(CO)(dppe)<sub>2</sub>] (<strong>2</strong>), as well as <i>trans</i>-[FeBr(RCN)(depe)<sub>2</sub>]BF<sub>4</sub> (<strong>3</strong>) (R = 4-MeOC<sub>6</sub>H<sub>4</sub> (<strong>3a</strong>), 4-MeC<sub>6</sub>H<sub>4</sub> (<strong>3b</strong>), C<sub>6</sub>H<sub>5</sub> (<strong>3c</strong>), 4-FC<sub>6</sub>H<sub>4</sub> (<strong>3d</strong>), 4-O<sub>2</sub>NC<sub>6</sub>H<sub>4</sub> (<strong>3e</strong>), Me (<strong>3f</strong>), Et (<strong>3g</strong>), 4-MeOC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub> (<strong>3h</strong>); depe = Et<sub>2</sub>PCH<sub>2</sub>CH<sub>2</sub>PEt<sub>2</sub>), novel <i>trans</i>-[FeBr(CO)(depe)<sub>2</sub>]BF<sub>4</sub> (<strong>4</strong>) and <i>trans</i>-[FeBr<sub>2</sub>(depe)<sub>2</sub>] (<strong>5</strong>) undergo, as revealed by cyclic voltammetry at a Pt-electrode and in aprotic non-aqueous medium, two consecutive reversible or partly reversible one-electron oxidations assigned as Re<sup>I</sup> → Re<sup>II</sup> → Re<sup>III</sup> or Fe<sup>II</sup> → Fe<sup>III</sup>&nbsp;→ Fe<sup>IV</sup>. The corresponding values of the oxidation potentials <sup>I</sup><i>E</i><sub>1/2</sub><sup>ox</sup> and <sup>II</sup><i>E</i><sub>1/2</sub><sup>ox</sup> (waves I and II, respectively) correlate with the Pickett's and Lever's electrochemical ligand and metal site parameters. This allows to estimate these parameters for the various nitrile ligands, depe and binding sites (for the first time for a Fe<sup>III/IV</sup> couple). The electrochemical ligand parameter show dependence on the "electron-richness" of the metal centre. The values of <sup>I</sup><i>E</i><sub>1/2</sub><sup>ox</sup> for the Re<sup>I</sup> complexes provide some supporting for a curved overall relationship with the sum of Lever's electrochemical ligand parameter. The Pickett parametrization for closed-shell complexes is extended now also to 17-electron complexes, <i>i.e.</i> with the 15-electron Re<sup>II</sup> and Fe<sup>III</sup> centres in <i>cis</i>-{[ReCl(dppe)<sub>2</sub>]}<sup>+</sup> and <i>trans</i>-{FeBr(depe)<sub>2</sub>}<sup>2+</sup>, respectively. <p>

Title:Redox Potential - (Electronic) Structure Relationships in 18- and 17-Electron Mononitrile (or Monocarbonyl) Diphosphine Complexes of Re and Fe
Creators:
Guedes Da Silva, M. Fátima C.
Martins, Luísa M. D. R. S.
Fraústo Da Silva, João J. R.
Pombeiro, Armando J. L.
Uncontrolled Keywords:Carbonyl complexes, Nitrile complexes, Cyclic voltammetry, Redox potential, Electrochemistry, Iron, Rhenium
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:66
Number:1
Page Range:pp. 139-154
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20010139UNSPECIFIED
ID Code:1782
Item Type:Article
Deposited On:06 Feb 2009 17:12
Last Modified:06 Feb 2009 16:12

Citation

Guedes Da Silva, M. Fátima C.; Martins, Luísa M. D. R. S.; Fraústo Da Silva, João J. R.; Pombeiro, Armando J. L. (2001) Redox Potential - (Electronic) Structure Relationships in 18- and 17-Electron Mononitrile (or Monocarbonyl) Diphosphine Complexes of Re and Fe. Collection of Czechoslovak Chemical Communications, 66 (1). pp. 139-154. ISSN 0010-0765

Repository Staff Only: item control page