An Electron‐Deficient Cp^E Iridium(III) Catalyst: Synthesis, Characterization, and Application to Ether‐Directed C−H Amidation

Abstract

The synthesis, characterization, and catalytic performance of an iridium(III) catalyst with an electron‐deficient cyclopentadienyl ligand ([CpEIrI2]2) are reported. The [CpEIrI2]2 catalyst was synthesized by complexation of a precursor of the CpE ligand with [Ir(cod)OAc]2, followed by oxidation, desilylation, and removal of the COD ligand. The electron‐deficient [CpEIrI2]2 catalyst enabled C−H amidation reactions assisted by a weakly coordinating ether directing group. Experimental mechanistic studies and DFT calculations suggested that the high catalytic performance of [CpEIrI2]2 is due to its electron‐deficient nature, which accelerates both C−H activation and IrV‐nitrenoid formation.

Cobalt-Catalyzed (3 + 2) Cycloaddition of Cyclopropene-Tethered Alkynes: Versatile Access to Bicyclic Cyclopentadienyl Systems and Their CpM Complexes

“…Overall, our methodology provides a direct, robust, and versatile entry into a broad variety of highly substituted bicyclic cyclopentadienes, which are difficult to obtain using alternative procedures . Among different applications, cyclopentadienes can be used for the synthesis of cyclopentadienyl metal complexes (“CpML n ”), a type of organometallic species that has found countless applications in catalysis. , It is well known that the electronic characteristics of these Cp ligands can have a significant influence on the reactivity of the derived Cp-metal catalyst, especially in the case of electron-deficient Cps . However, routes to prepare highly electronically deficient Cps are scarce and have low versatility.…”

“…Moreover, the bicyclic cyclopentadienyl products of type 2 can also be used to prepare related Cp-iridium counterparts. In this case, the Ir­(I) complex was prepared using [Ir­(cod)­OAc] 2 as the iridium­(I) source, and the resulting Ir­(III) complex was obtained following a two-step protocol through the carbon monoxide derivatives of type [CpIrI 2 (CO)] (Scheme b). , Remarkably, a comparison of the CO stretching frequencies of the carbonyl iridium precursors [ Cp 2p Ir­(CO)­I 2 ] (2064.9 cm –1 ) and [ Cp 2n Ir­(CO)­I 2 ] (2065.4 cm –1 ) with those of previously reported counterparts, confirmed that these are probably the ones with the highest electron-deficient character…”