Oxygen ligands metallic mixtures

In a recent review it was argued that such additives of copper, benzoquinone, and HPMOV are not really needed all that is needed is the presence of oxidation-resistant ligands that prevent palladium metal formation [15]. Indeed, activation of the C-H bond is not as slow as, for example, the Wacker reaction of ethene in which reoxidation of palladium must be performed by copper oxidation, although in this catalytic system the additives may still play a role in stabilizing the intermediate low-valent palladium species and thus prevent catalyst decomposition. This thesis was corroborated by the work of de Vos and Jacobs, who showed that addition of benzoic acid to the oxidative arylation reaction in the presence of oxygen led to superior results in the coupling of a variety of substituted arenes with acrylates, cinnamates, and ,/f-unsaturated ketones. Very good yields and TON up to 762 were obtained at 90 °C. A mixture of the o, m, and p isomers is obtained if substituted arenes are used [16]. 

Alkylated rare-earth metal complexes with rare-earth metal centers surrounded exclusively by oxygen donor ligands were reported from facile ligand redistribution processes in 2,6-dimethylphenolate/trialkylaluminum mixtures. As shown in Scheme 29 for the yttrium derivatives Y(0ArMe,II)2[(//-OArMe>H)2AlR2](THF)2 (R= Me, Et), heterobimetallic 1 1-species were ac-... 

---