Aromatic para-functionalized NCN pincer compounds

• Published in: Journal of organometallic chemistry Vol. 845; pp. 229 - 257
• Main Authors: Valdés, Hugo, González-Sebastián, Lucero, Morales-Morales, David
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2017
• Subjects: Bioorganometallic chemistry; Catalysis; Dendrimers; Metallopincer; Pincer compounds; Polymer supported; Bioorganometallic chemistry; Pincer compounds; Dendrimers; Metallopincer; Catalysis; Polymer supported
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2017.05.034

The initial virtues of pincer compounds of robustness and high reactivities, and thus their potential applications of these species in homogenous catalysis, have lead to research involving the potential recovery and recycling of these catalysts. The simplest idea, the supporting of the pincer complexes on different platforms that span form dendrimers to solid supports to polymers, etc. has in turn lead to the development of experimental procedures designed for the functionalization of the aromatic ring of the main backbone of the pincer compounds, mainly on the para position. This privilege position has allowed the functionalization of a number of pincer complexes, without compromising their reactivities. These discoveries, indirectly have opened new areas of research in which pincer compounds have impacted in the last 30 years by the mere change of the substituent on the 4-position (para position) of the aromatic ring on the basic backbone of pincers. This chemistry has been especially prolific in the case of NCN pincer ligands and their complexes, since synthetic methods to produce para-functionalized SCS, PCP, POCOP and so on, are often long and tedious and usually afford the compounds of interest in low yields. Nevertheless, this has not discouraged the research on these pincer species, on the contrary, has motivated the generation of experimental procedures that, nowadays produce some of these species in a single step in high yields, opening an exciting avenue of opportunities. Thus, this paper comprehensively reviews some of the most relevant advances and applications of aromatic para-functionalized NCN pincer compounds, as well as selected examples of other pincer systems (i.e. SCS, PCP, POCOP, etcetera). The development of experimental procedures for the functionalization of the aromatic ring of the main backbone of pincer compounds, mainly at the para position, has allowed the synthesis of a number of pincer complexes, without compromising their reactivities. This being particularly true in the case of NCN pincer systems. This, “Teaching old dogs new tricks” has opened new areas of opportunity such as biology, medicine and material science in which pincer compounds may have a strong impact. [Display omitted] •The state of the art on the functionalization of aromatic pincer compounds is reviewed.•The diverse applications of para-substituted aromatic pincer compounds are revised.•The various procedures for the synthesis of para-functionalized aromatic pincer compounds are reviewed.