BICAAC-Derived
Covalent and Cationic Ir(I) Complexes:
Application of Ir(BICAAC)Cl(COD) Complexes as Catalysts for Transfer
Hydrogenation and Hydrosilylation Reactions
posted on 2024-01-09, 07:44authored byMandeep Kaur, Manu Adhikari, Krishna K. Manar, Yuvraj Yogesh, Darsana Prakash, Sanjay Singh
The ambiphilic bicyclic (alkyl)(amino)carbenes (Me/iPrBICAAC) upon reaction with [IrCl(COD)]2 smoothly
afford
mononuclear Ir(I) complexes that have been spectroscopically and structurally
characterized. These complexes exhibit good catalytic activity for
transfer hydrogenation (TH) of 4-chlorobenzaldehyde using isopropyl
alcohol (iPrOH), with turnover frequency values ranging between 6269
and 8093 h–1. Choosing the covalent complex Ir(MeBICAAC)Cl(COD) as a catalyst, a wide array of carbonyls and
imines functionalized with electron-withdrawing and electron-donating
substituents have been surveyed and afforded their reduced products
in moderate-to-good yields. No detachment of the BICAAC unit from
the Ir center was observed upon prolonged heating of Ir(MeBICAAC)Cl(COD) in toluene-d8 or isopropyl
alcohol-d8, which evidenced good thermal
stability of the catalyst. Complex Ir(MeBICAAC)Cl(COD)
was also found to be catalytically active for the hydrosilylation
of a variety of aldehydes using triethylsilane (Et3SiH).