First “Click” Synthesis of the Ribbed‐Functionalized Metal Clathrochelates: Cycloaddition of Benzyl Azide to Propargylamine Iron(II) Macrobicycle and the Unexpected Transformations of the Resulting Cage Complex

Abstract

AbstractA bis(propargylamine) iron(II) cage complex was obtained in high yield by nucleophilic substitution of reactive chlorine atoms of its dichloroclathrochelate precursor with an excess of propargylamine in acetonitrile. The macrobicyclic product undergoes copper(I)‐catalyzed “click” reaction with benzyl azide giving the copper(II)‐containing complex of the bis(benzyl‐1,2,3‐triazolylmethylamine) clathrochelate ligand: the Cu2+ ion coordinates two deprotonated amino groups and two donor azaheterocyclic fragments of the ribbed substituents of the macrobicyclic ligand. Demetallation of this copper(II) complex with potassium cyanide gave target clathrochelate as a minor product. The major macrobicyclic product of this demetallation containing one inherent amino group and one benzyl‐1,2,3‐triazolylmethylamine ribbed substituent resulted from the side dealkylation reaction. The complexes obtained were characterized using elemental analysis, MALDI‐TOF mass spectrometry, IR, UV/Vis, 1H and 13C{1H} NMR spectroscopy, and by X‐ray diffraction. The geometry of their FeN6 coordination polyhedra is intermediate between a trigonal prism and a trigonal antiprism.