ISSN:
1572-901X
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Summary The formation of complexes between Fe3+ and 2,4-dinitrophenol, 4-nitrophenol and 4-methylphenol is studied in dimethylsulphoxide solution. The reaction proceeds almost to completion and the occurrence, in solution, of complexes with higher stoichiometry than 1∶1 is reported for the first time. The following stability constants are determined (25 °C, 0.1 M KClO4): FeIII-2,4-dinitrophenolate β1=1.8×103, β2=4.4×105; FeIII-4-nitrophenolate β1=1.10×107, β2=2.5×1012 β3=3.9×1016; FeIII-4-methylphenolate β=1.7×1012. The binding of a phenolate ligand to iron(III) strongly decreases its affinity for other phenolate ligands. The superior σ-donor, 4-methylphenolate (OC6H4Me)−, only forms a 1∶1 complex, Fe(OC6H4Me)2+. The e.s.r. spectrum of this species clearly prove it is a true iron(III) complex and does not contain iron(II), in opposition to recent claims. However, the complex Fe(OC6H4Me)2+ easily undergoes a ligand-to-metal electron transference. Addition of an excess of 1,10 phenanthroline yields the iron(II) complex [Fe(o-phen)3]2+ instantaneously.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00618167
Permalink