An η¹-Aldehyde Complex and the Role of Hydrogen Bonding in Its Conversion to an η¹-Imine Complex

Abstract

2-Pyridinecarboxaldehyde displaces Me 2 CO from [IrH 2 (Me 2 CO) 2 (PPh 3 ) 2 ] + to give a chelating N,O-bound product containing an η 1 -O-bound aldehyde group. This is converted to the η 1 -N-bound imine complex with a variety of substituted amines. When the amine contains a suitably positioned −OH group, intramolecular O−H···H−Ir dihydrogen bonds are detected in the products. This hydrogen bonding influences the relative rates of product formation from 2- and 4-aminophenol (rate ratio 6:1), where only the 2-isomer is capable of forming an intramolecular H-bond.