Metall‐π1‐Komplexe von Benzolderivaten, XLI. Bis(η 6 1‐anilin)chrom: Synthese, Redoxverhalten und Brønsted‐Basizität
| Autor: | Christoph Elschenbroich, Stefan Hoppe, Bernhard Metz |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Trimethylsilyl
Inorganic chemistry chemistry.chemical_element Medicinal chemistry Redox Acid dissociation constant law.invention Inorganic Chemistry Metal chemistry.chemical_compound Chromium Aniline chemistry Sandwich compound law visual_art visual_art.visual_art_medium Electron paramagnetic resonance |
| Zdroj: | Chemische Berichte. 126:399-404 |
| ISSN: | 0009-2940 |
| Popis: | Metal π Complexes of Benzene Derivatives, XLI[1]. — Bis(η61-aniline)chromium: Synthesis, Redox Properties and Bronsted Basicity Bis(η61-aniline)chromium (6) has been prepared by protodesilylation of its N,N,N′,N′1-tetrakis(trimethylsilyl) derivative 5, which is accessible by metal-atom ligand-vapor cocondensation (cc). Bis(η61-dimethylaniline)chromium (3) is obtained directly from cc. The couples 3+/0 and 6+/0 feature the most negative redox potentials E1/2 ever reported for bis(arene)1-metal complexes. According to EPR spectroscopy, applied to the radical cations 3+· and 6+· the site of oxidation is largely localized on the metal. The pH dependence of E1/2 is cast in Nerst-Clark plots, whose breaks supply the pKs values of the mono-and diprotonated forms of 3 and 6. η61-Coordination to CrI increases the basicity of aniline by three pK units, whereas η61-coordination to Cr1 effects a decrease by more than seven pK units. The first and second dissociation constants of the organometallic bis(ammonium) ions 3(H+)2 and 6(H+)2 differ by 2.7 pK units. This interval reflects the interaction of the two basic centers in 3 and 6 which approaches that of p1-phenylenediamine. Thus, conjugation across the bis(η61-arene)chromium unit is virtually uninhibited. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text