Bond Activation with Low-Valent Nickel in Homogeneous Systems

作者：Arevalo Alma; Garcia Juventino J^*

来源：European Journal of Inorganic Chemistry, 2010, 2010(26): 4063-4074.

DOI：10.1002/ejic.201000621

• Homogeneous catalysis
• Nickel
• Isomerization
• Desulfurization
• Hydration
• Bond activation
• Nitriles
• Alkynes

The activation of unreactive bonds has been a topical issue for a number of years and still represents a challenge in organometallic chemistry and catalysis, particularly in research areas dealing with the functionalization of C-C, C-H, C-S, C-N, C-F, C-Cl and C-O bonds.([1]) The refractory, pseudo-halogen C-CN bonds are also considered among these. As an example, the C-CN bond in CH(3)CN is stronger than the related C-F bond in CH(3)F (122 vs. 108 kcal/mol).([2]) With the use of the right metal moiety however, the C-CN bond in several organic substrates can be cleaved and functionalized or isomerized effectively. Their activation is of major relevance in both industry and in laboratory scale, allowing the preparation of bulk chemicals, as well as fundamentally important organic and organometallic intermediates.
In industry, adiponitrile (AN) is synthesized by the catalytic double hydrocyanation of butadiene. As discussed below (vide infra) one of the key steps in the process consists on the isomerization of the branched 2-methyl-3-butene-nitrile (2M3BN) to the linear 3-pentenenitrile (3PN), a process that involves the cleavage and formation of a C-CN bond (Scheme 1). The AN is considered relevant for the industry being the precursor of 1,6-hexamethylenediamine, which is then used to obtain Nylon 6,6.([3])
Despite the relevance of this reaction, there are still many mechanistic details to be determined and fully understood, several of which remain buried in patents. Inspired on these facts, our group has been involved in the study of the isomerization reaction of nitriles. The latter study has been undertaken concertedly with other related useful transformations that involve alkyl and aromatic nitriles, as is the case of their catalytic hydration. The coordination mode of nitriles to low-valent nickel has been an invaluable tool to understand their reactivity and this been exhaustively examined. Finally, additional studies by the group concerning the reactivity of the nickel moieties assisting the catalytic desulfurization of refractory organic substrates is also addressed in the current review in the context of related studies by other research groups.

• 出版日期2010-9