Palladium nickel-containing synthetic

Raffinate Hydrocracking with Palladium-Nickel— Containing Synthetic Mica-Montmorillonite Catalysts... 

Subsequent work reported some improvements on this chanistry when nickel catalysts were used, particularly for the formation of silyl aryl ethers. However, another tQ)proach was the use of phosphines that are weaker donors than standard triarylphosphine ligands. Use of a palladium catalyst containing a DPPF analog bearing p-CFj groups on each phaiyl ring led to improved yields as part of the first examples of Pd-catalyzed formation of diaryl ethers from aryl haUdes (Eq. A)P Nonetheless, neither of these changes in catalyst composition led to the formation of aryl ethers from unactivated aryl hahdes in a synthetically valuable fashion. 

The catalyst for the second stage is also a bifimctional catalyst containing hydrogenating and acidic components. Metals such as nickel, molybdenum, tungsten, or palladium are used in various combinations and dispersed on sofid acidic supports such as synthetic amorphous or crystalline sihca—alumina, eg, zeofites. These supports contain strongly acidic sites and sometimes are enhanced by the incorporation of a small amount of fluorine. 

N-containing, in cobalt(III) complexes, 7, 28 in nickel complexes, 8, 120 palladium complexes, 8, 276 synthetic applications corroles, 1, 70... 

A number of nickel(O) catalysts have been synthesized since the initial report of Arduengo et al. containing nickel and palladium NHC catalysts [10]. The work of Matsubara et al. [11] shows the ability to access similar nickel(O) and nickel(II) catalysts from commercially available Ni(acac)2 (Figure 13.2). This synthetic route, which employs sodium hydride to reduce Ni(II) to Ni(0), circumvents the need to use air-sensitive and flammable Ni(COD)2. One other catalyst of note is the 18 e complex synthesized by Spicer and coworkers [12]. The unique structure of the tetradentate NHC ligand serves to stabilize the catalyst as well as facilitate the reduction of several organic structural motifs. 

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