Palladium supported on zinc ferrite: an efficient catalyst for ligand free C-C and C-O cross coupling reactions

An efficient superparamagnetic Pd-ZnFe2O4 solid catalyst has been synthesized by loading Pd(0) species on zinc ferrite nanoparticles. Sonogashira cross couplings between terminal alkynes and aryl halides were achieved in the absence of any Cu co-catalyst. A Heck-Matsuda coupling reaction of structurally different aryldiazonium tetrafluoroborate substrates was preceded at 40 °C in water. Cyanation of aryl halides was successfully done using K4[Fe(CN)6] as the cyanide source over Pd-ZnFe2O4. The catalyst was also employed for Ullmann type cross coupling reactions. Excellent yield of the products, reusability, and uncomplicated work-up make this catalyst efficient for C-C and C-O coupling reactions. Good yield of products, easy separation, and negligible leaching of Pd from the catalyst surface confirm the true heterogeneity in these catalytic reactions.