Well-Defined Ir/Pd Complexes with a Triazolyl-diylidene Bridge as Catalysts for Multiple Tandem Reactions

Abstract

The ligand 1,2,4-trimethyl-triazolyl-diylidene has been used for the preparation of a series of three iridium/palladium heterometallic complexes that have been fully characterized. The presence of the two different metals allows tandem processes to be designed by combining reactions that are typically catalyzed by Ir and Pd. Three tandem reactions have been studied: dehalogenation/transfer hydrogenation of haloacetophenones, Suzuki-coupling/transfer hydrogenation of p-bromoacetophenone, and Suzuki-coupling/alpha-alkylation of p-bromoacetophenone. All three reactions yielded excellent outcomes to the corresponding final products, with the relevant feature that the heterodimetallic complexes are more active than the sum of the corresponding homodimetallic species. All three catalytic reactions reported here constitute unprecedented examples of tandem approaches to complex organic molecules.

Hydrodefluorination of carbon–fluorine bonds by the synergistic action of a ruthenium–palladium catalyst

“…Figure 2 shows the complexes under study in this work. All three complexes were obtained from 1,2,4-trimethyl-triazolium tetrafluoroborate, following similar synthetic procedures as those that we have previously reported [33][34][35][36][37][38][39] . The preparation of the Pd-Ru heterodimetallic complex 3 was achieved by the stepwise deprotonation of the triazolium salt, followed by the subsequent addition of the corresponding metal source, as schematically shown in Fig.…”

“…1) [33][34][35][36][37][38][39] . The preparation of such types of heterodimetallic complexes allowed us to study several catalytic processes in which each metal fragment facilitated a mechanistically different cycle 33,35,36,40 . We also confirmed that the presence of the two different metals furnish catalytic benefits compared with the cases in which mixtures of homodimetallic species are used.…”

Iridium, ruthenium, and palladium complexes containing a mesoionic fused imidazolylidene ligand

“…complexes in hydrogen transfer catalysis [81][82][83][84][85][86][87], the catalytic activity of complex 2a was investigated in transfer hydrogenation using iPrOH as sacrificial hydrogen donor. In a representative reaction, benzophenone was used as model substrate (Scheme 3).…”

Recent Developments in the Applications of Palladium Complexes Bearing N-Heterocyclic Carbene Ligands

“…Recently, a series of iridiumpalladium complexes have been described. 117 The synthetic strategy for the preparation of the heterobimetallic Ir/Pd complexes consist of the monofunctionalization of the dicationic salt 1,2,4-trimethyltriazolium bis(tetrafluoroborate) to obtain the cationic iridium complex 42. In complex 42, the ditz ligand acts as a monocarbene and still has other acidic proton that can be activated to generate a second heterobimetallic complex.…”