The reactions of metal acetylacetonates with acids

Abstract

The reactions of a number of metal acetylacetonates with trifluoroacetic acid have been investigated using nmr. The initial reaction involves protonation on the carbon atom of the ligand. In the case of the aluminum compound in coordinating solvents there is further reaction to give cationic complexes. The results are used to reinterpret the kinetics of ligand exchange for this compound. It is argued that, contrary to previous suggestions, the slow step is the breaking of the first metal oxygen bond to form a dangling ligand intermediate. A consequence of this conclusion is that intramolecular rearrangements of Al(III) β diketonates must proceed by twisting rather than by bond rupture mechanisms.