Tuning the Tetraarylcyclopentadienones from iron tricarbonyl complexes: effects in Transfer Hydrogenation and solubility

Abstract

The nature of the ligands coordinated to the metal in cyclopentadienone iron tricarbonyl (CIC) complexes is important for the activation or H transfer steps of Transfer Hydrogenation (TH) catalysis. Previous reports showed an existing correlation between the electron-donating or -withdrawing nature of substituents appended to phenyl groups at 3,4 positions of tetraarylcyclopentadienones and the catalytic efficiency of the related CICs. Here we extend these studies to phenyl groups at positions 2,5. Our results show that careful selection of the substituent groups apended to the different aryl groups of tetraarylcyclopentadienone improves the solubility of CIC complexes on protic solvents, or rescues the catalytic efficienty for TH reactions on complexes carrying electron-withdrawing groups in their arene.