Stereoisomerism of dihalodiaryl(acetylacetonato)-antimony(V) compounds

A series of dihalodiaryl(acetylacetonato)antimony(V) compounds, (p-Y-C₆H₄)₂SbX₂Acac (X=F, Cl, Br; Y=NO₂, Cl, H, CH₃, CH₃O), were prepared. All of these compounds are monomeric and exist in solution as a mixture of two isomers both with chelated hexacoordinate configurations. From the temperature- and solvent-dependent PMR spectra of these compounds, it is concluded that the two isomers are in equilibrium in solution. The assignments of the PMR signals to the isomers were made by considering the effects of solvent and the substituents X and Y on the spectra.