Ru-arene complexes

A stoichiometric example of the combination of two reagents has recently been reported by O Connor in the context of the Bergman cycloaromatization. The generation of the aromatic diradical can be induced by [Cp Ru(CH3CN)3]PF6. Radical reduction occurs through HAT from CpW(CO)3H to provide a cationic Ru-arene complex as shown in Scheme 15 [35]. 

There is a wider general interest in understanding the oxidation of cysteine thiolates in proteins since they are involved in redox-sensing reactions [99], Therefore, such oxidation reactions of thiols induced by Ru coordination may also play a more general role in the pharmacological activity of Ru-arene complexes by coupling Ru coordinative binding to redox processes both outside and inside cells. 

Dinuclear Ru-arene, complexes based on maltol-derived ligands with a varying spacer length (Fig. 9) were shown to exhibit high in vitro anticancer activity [64,65], whereas the mononuclear analogue was inactive [66]. In another approach, two organometallic Ru-arene moieties were linked via a ferrocene unit (Fig. 10)... 

To allow a stable encapsulation of these two types of enzyme inhibitors into their organometallic cages, Therrien and coworkers connected them to pyrene derivatives (Figure 1.21). The encapsulation of the pyrenyl group into the cage is driven by hydrophobicity and n-n interactions. Of note, the successful encapsulation of the compounds was confirmed by diverse NMR, X-ray crystallography, and ESI-MS techniques. In the case of the Ru arene complexes, an increase in... 

The second one is a Ru-arene complex. The stable, commercially available dimeric Ru(II) complex ([RuCl2(p-cymene)]2) constitute good activity for the ROMP reaction. Just as the Shiff base modified complex, the Ru-arene complexes present a high functional group tolerance, which permits the polymerization of monomers bearing acetal, ether, ester and acid functionalities [10]. 

Over the last decade, our group has shown in multiple instances that monometallic Ru catalysts active in olefin metathesis could also be turned into efficient promoters for atom transfer radical reactions with only minor ligand tuning. Such a dual activity was evidenced, among others, for Grubbs catalyst Ru-arene complex 3, Herrmann bis-NHC or mixed-... 

Bimetallic Ru complexes nicely complement the ubiquitous Grubbs alkyli-dene catalysts and related species used as initiators for olefin metathesis. Compared to their monometallic counterparts, they often display a greater propensity at releasing coordinatively unsaturated species essential for the activation of alkene substrates toward metathesis. In the case of homobi-metalUc Ru-arene complexes, the choice of the ancillary ligand was found crucial to achieve high metathetical activities. Thus, complexes 16a and (to a lesser extent) 16b bearing NHC ligands were very efficient catalyst precursors for various types of olefin metathesis reactions, whereas phosphine-based... 

Orbisaglia S, Di Nicola C, Marchetti P, et al. New Ru"(arene) complexes with halogen-substituted bis- and tris(pyrazol-l-yl)borate Ugands. Chem Eur J. 2014 20 3689-3704. 

Noyori Asymmetric Transfer Hydrogenation Noyori s well-designed chiral Ru -arene complexes catalyze the asymmetric transfer hydrogenation of ketones and imines (not shown) with stable organic hydrogen donors such as 2-propanol [69]. The reaction is reversible, and the involved chiral ruthenium species and the proposed transition state are depicted in Scheme 2.140. 

---