Bimetallic Substituted Ceria: An Alternative Approach to Ligand-Free Heck-Mizoroki Cross-Coupling Reactions

This work describes Ce(0.89)Zr(0.03)Pd(0.08)O(2-delta)as a heterogeneous catalyst for Heck-Mizoroki reactions. The material was synthesised by urea-assisted solution combustion to give a zirconium-stabilised cerium fluorite structure, with a fraction of palladium incorporated into the host structure. Characterisation techniques included ICP-OES, P-XRD and electron microscopy. The catalyst illustrated a high TOF of 1860 h(-1)for the cross-coupling of iodobenzene with methyl acrylate, when trimethylamine (TEA) was used as a base and dimethylformamide (DMF) as the solvent at 130 degrees C. To establish the activity of coupling pairs, screening was limited to aryliodobenzenes, with various electronic properties, to determine the influence of aryliodobenzene electronic density on the trans product yield. Electron-donating substituents showed good yields, while electron-withdrawing groups had lower yields. Furthermore, various classes of electron-deficient olefins were screened to determine any effect on the trans product yield. Electron-deficient olefins showed higher yields with regard to the trans product than neutral styrene.