A Ferrous Center as Reaction Site for Hydration of a Nitrile Group into a Carboxamide in Mild Conditions

Mild conversion of the nitrile substituent into an amide functional group is observed upon coordination of CNTPA [CNTPA = (6-cyano 2-pyridylmethyl)bis(2-pyridylmethyle)amine] to FeCl2 followed by reaction with water. The crystal structure of CNTPAFeCl2 is reported and reveals that the nitrile group does not coordinate but is activated in the vicinity of the ferrous center. Upon treatment with water under anaerobic conditions, CNTPAFeCl2 converts into H2NCOTPAFeCl2, [H2NCOTPA = (6-carboxamido 2-pyridylmethyl)bis(2-pyridylmethyle)amine], the X-ray crystal structure of which is reported. The new ligand H2NCOTPA can easily be obtained upon decomplexation.