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Synthesis of new octakis(benzylthio)tetraazaporphyrin complexes with bivalent transition metal ions and an investigation of their spectral, redox and catalytic properties
| Content Provider | Semantic Scholar |
|---|---|
| Author | Prasad, Rajendra Kumar, Ajay |
| Copyright Year | 2004 |
| Abstract | Transition metals in the +2 oxidation state form complexes with octakis(benzylthio)tetraazaporphyrin [M{TAP(SBn)8}] (M=Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and 2H+; Bn=CH2Ph; TAP=tetraazaporphyrin) and were prepared via demetallation of the template-synthesized complex [Mg{TAP(SBn)8}] in ClCH2COOH, followed by insertion of the metal ions in a PhCl–DMF mixture. All compounds were characterized by u.v–vis, 1H-n.m.r., e.s.r. and mass spectra, microanalyses and magnetic susceptibility data. PM3 geometry optimization showed near coplanar arrangement of five phenyl rings vis-à-vis the TAP ring plane, while the remaining three phenyl rings lie bent over it. The Mn2+, Co2+ and Cu2+ complexes exhibited reversible one electron oxidation waves, that were observed at E1/2 -0.33, -0.29 and 0.58 V versus Ag/AgCl respectively. They all exhibited an irreversible reduction wave at Ep -1.1 V versusAg/AgCl followed by appearance of an irreversible oxidation wave at Ep 1.1–1.2 V versus Ag/AgCl. This has been interpreted in terms of reductive dissociation, leading to removal of the benzyl substituents, and subsequent oxidation of thiolate products. The Mn2+, Co2+ and Cu2+complexes exhibited metal ion-based e.s.r. signals. The [Co{TAP(SBn)8}] complex in a homogeneous DMF solution was found to catalyze electro-reduction/oxidation of nitrite ions. In the presence of a 1/5 molar quantity of the complex [Co{TAP(SBn)8}], the nitrite reduction peak was observed to be shifted by 0.1 V towards the positive potential side and the peak current rose by a factor of 1.33. Similarly a sharp rise in the anodic current, corresponding to oxidation of nitrite ions, was observed in the presence of the complex. |
| Starting Page | 714 |
| Ending Page | 721 |
| Page Count | 8 |
| File Format | PDF HTM / HTML |
| DOI | 10.1007/s11243-004-0385-3 |
| Alternate Webpage(s) | https://page-one.springer.com/pdf/preview/10.1007/s11243-004-0385-3 |
| Alternate Webpage(s) | https://doi.org/10.1007/s11243-004-0385-3 |
| Volume Number | 29 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
