Transition metal catalysis nickel complexes

In this context, homogeneous catalysis has been increasingly used since it can offer valuable advantages, notably in terms of selectivity and efficiency. Indeed, low-valent complexes of transition metals like nickel, palladium, or cobalt can react with many functionalities, thus allowing numerous C,C-bond forming reactions. 

Our synthetic method for CO2 fixation was based on the use of transition-metal catalysis combined with electrochemical techniques [10]. Within this methodology, the electrochemical CO2 fixation into some alkenes has been reported to afford carbo lic acids in a reductive hydrocarboxylation-tjqje reaction catalyzed by nickel complexes, under mild conditions [11]. The electrocarboxylation of organic halides to the corresponding carboxylic acids has also been reported [12], yields and efficiency of the reaction being strongly dependent on the reaction conditions. 

The nickel complex displays a strong coordination of silylene chelate ligand to the nickel center. The COD and TMS groups at the nickel and bridging phosphorus atom provide sufficient steric stability to the complex. The nickel complex can be promising toward transition metal catalysis toward C—C bond coupling reactions. 

The catalytic cyclo-oligomerization of 1,3-butadiene mediated by transition-metal complexes is one of the key reactions in homogeneous catalysis.1 Several transition metal complexes and Ziegler-Natta catalyst systems have been established that actively catalyze the stereoselective cyclooligomerization of 1,3-dienes.2 Nickel complexes, in particular, have been demonstrated to be the most versatile catalysts.3... 

After that, studies on the palladium-catalyzed reactions of conjugated dienes attracted little attention. They have only been reexamined since the late 1960 s. The scope of the reaction of butadiene catalyzed by palladium complexes has gradually been established. The catalysis by palladium is different from those of other transition metals. Although palladium is located below nickel in the periodic table, the catalytic... 

Carbon-carbon bond-forming reactions are one of the most basic, but important, transformations in organic chemistry. In addition to conventional organic reactions, the use of transition metal-catalyzed reactions to construct new carbon-carbon bonds has also been a topic of great interest. Such transformations to create chiral molecules enantioselectively is therefore very valuable. While various carbon-carbon bond-forming asymmetric catalyses have been described in the literature, this chapter focuses mainly on the asymmetric 1,4-addition reactions under copper or rhodium catalysis and on the asymmetric cross-coupling reactions catalyzed by nickel or palladium complexes. 

The NiY zeolite was also shown to be active for the cyclotrimerization of propyne with 1,2,4-trimethylbenzene being the main product. The activities of the above-mentioned transition metal ions for acetylene trimerization are not so surprising since simple salts and complexes of these metals have been known for some time to catalyze this reaction (161, 162). However, the tetramer, cyclooctatetraene, is the principal product in homogeneous catalysis, particularly when simple salts such as nickel formate and acetate are used as catalysts (161). The predominance of the trimer product, benzene, for the zeolite Y catalysts might be indicative of a stereoselective effect on product distribution, possibly due to the spatial restrictions imposed on the reaction transition-state complex inside the zeolite cages. 

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