The kinetics and mechanism of the substitution of benzylideneacetone by azadienes in the irontricarbonylbenzylideneacetone complex

Abstract

The kinetics of the substitution reactions of benzylideneacetone (bda) by the azadienes 2,2'-bipyridine (bipy), 2-acetylpyridineanil (apa), and diacetyldianil (dad), in the Fe(bda)(CO)(3) complex was performed in toluene in the temperature range between 40 and 55 degrees C. The results of this study showed that the mechanism of the reactions with bipy and dad - which are symmetric ligands, aromatic and aliphatic, respectively - involves two parallel reaction paths, one being dissociative and the other associative. In the case of apa - a asymmetric ligand - only the dissociative path is operative, leading to a half-bonded intermediate. The next step leads to the formation of two different new intermediates, depending on whether the incoming ligand nitrogen atom is aliphatic or aromatic.