Addition of O–H, N–H, and F–H Bonds across a Boryl–Iridium Unit

Abstract

(PBP)Ir(CO)2 possesses a Lewis acidic boryl center and a basic monovalent Ir center. Heterolytic cleavage of O–H, N–H, and F–H bonds by this molecule was examined. (PBP)Ir(CO)2 reacted with water, methanol, ethanol, cyclohexanol, phenols, benzoic acid, and triethylamine trihydrofluoride to add the O–H and F–H units across the B–Ir bond with preservation of both carbonyl ligands. For the benzoate adduct, one of the CO ligands is lost upon thermolysis with the benzoate bridging B and Ir. Thermolysis of (PBP)Ir(CO)2 with nBuNH2 ultimately resulted in a monocarbonyl product of the N–H cleavage with the resultant amido group bridging B and Ir. Dicarbonyl intermediates were observed in this reaction. Structures of the X–H cleavage products and the possible mechanistic pathways are discussed. Mechanistic experiments indicate that the reaction with ROH substrates proceeds by initial protonation of Ir, consistent with slower reactions with less acidic ROH substrates (and no reaction with tBuOH). For amines, the re...