Iridium arene containing

Finally, these aqueous suspensions of rhodium(O) and iridium(O) are the most efficient systems for the hydrogenation of a large variety of mono-, di-substituted and/or functionalized arene derivatives. Moreover, in our approach, the reaction mixture forms a typical two-phase system with an aqueous phase containing the nanoparticle catalyst able to be easily reused in a recycling process. 

More commonly encountered are the arene complexes also containing Cp or Cp ligands. Since [Cp IrCl2]2 (18) may be prepared so readily (see above), this provides a usefiil starting material for the formation of [Cp ( -arene)]+ compounds. (18) may be easily converted into [Cp Ir(acetone)3]+ by dissolution in acetone and treatment with Agppe]. Maiths has shown in a number of cases that this dication will then react with a variety of arenes including benzene, toluene, xylene, and naphthalene to yield arene complexes (27) by displacement of the acetones (equation 7). Maiths has also used [Cp Ir(OAc)2(OH2)] and [Cp Ir(NCCH3)3]+2 as sources of iridium. 

Heteroatom containing arenes have also been made to complex with transition metals, including iridium. For example, borabenzene has been shown to complex to iridium and iron in a single complex. ... 

Since the Run(arene) unit is isoelectronic with the Min(C5Me5) (M = Rh or Ir) moieties, studies have been performed in order to obtain ruthenium analogous complexes containing (/j-OH) or (/a-OR) groups as well as pyrazolate ligands but perhaps with new stoichiometries, which were not observed in rhodium or iridium chemistry (126). 

Reaction of TEMPO with [lr (TTP)(—CH2CH2CH2Ar)] species, desjnte the fact that these species also contain reactive benzyhc protons, only yields [(TTP)Ir Me]. This illustrates the importance of both the iridium center at the beta position and the arene at the alpha position to stabilize the carbon-centered... 

Intensive studies also showed that many transition metal complexes are able to catalyze aromatic C-H borylation of various arenes (Scheme 7), e.g., Cp Ir(H)(Bpin)(PMe3) [64,65], Cp Rh(Ti4-C6Me6) [65,66], ( 75-Ind)Ir(COD) [67], (776-mesitylene)Ir(Bpin)3 [67], [IrX(COD)]2/bpy (X = Cl, OH, OMe, OPh) [68-70]. A very recent study by Marder and his coworkers showed that [Ir(OMe)(COD)]2 can also catalyze borylation of C-H bonds in N-containing heterocycles [71]. For the Ir-catalyzed borylation reactions, it is now believed that tris(boryl)iridium(III) complexes [67,69], 40c, [72] are likely the reactive intermediates and a mechanism involving an Ir(III)-Ir(V) catalytic cycle is operative [67,69]. A recent theoretical study [73] provided further support for this hypothesis. A mechanism, shown in Scheme 8, was proposed. Interestingly, there are no cr-borane complexes involved in the Ir-catalyzed reactions. The very electropositive boryl and hydride ligands may play important roles in stabilizing the iridium(V) intermediates. 

More specifically, calculations have suggested that the ruthenium-alkyl complex in Equation 6.53 reacts with arene to exchange covalent ligands by a process closely related to a a-bond metathesis mechanism. Computational studies of the reactions of a simple iridium-alkyl and alkoxo complex with alkanes to generate new metal-alkyl complexes have also suggested that a mechanism is followed that involves many of the characteristics of a classic a-bond metathesis transition state. However, calculations of the mechanisms of these two processes imply that the transition state contains some degree of M-H bonding. 

B) [129]. In this case, the transformation could also be extended to olefins, giving P-disubstituted products containing either a benzene ring, a heterocycle, or an alkene. Li and co-workers reported a very complete study on the C-H alkynylation of arenes using TIPS-EBX 52 and either rhodium or iridium catalysts (Scheme 22,... 

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