The first monoribbed-functionalized tris-dioximate iron(II) clathrochelate with two inherent NH2-substituents, its reactivity, acid–base and coordination-chemical properties

The diamine bis-α-benzildioximate iron(II) clathrochelate with two inherent NH2-groups at one of the three ribbed fragments was obtained in a high yield by nucleophilic substitution of the dichlorine-containing macrobicyclic precursor with liquid ammonia. These amino-groups have an essential amide character and undergo deprotonation in the presence of strong bases. The resulted clathrochelate dianion behaves as an acido-ligand and coordinates to copper(II) ion giving the heteronuclear copper(II)–iron(II) complexes with the Cu(N−)4 coordination polyhedron. The reaction of this dianion with benzil afforded the clathrochelate product with annulated heterocyclic ribbed piperazinone fragment as a result of benzilic-type rearrangement with 1,2-shift of the phenyl substituent. mplexes obtained have been characterized using elemental analysis, MALDI-TOF, IR, UV–Vis, multinuclear NMR and EPR spectra, and X-ray crystallography. N6-coordination polyhedra of their encapsulated iron(II) ions possess a distorted trigonal-prismatic geometry.