Monoribbed-substituted mono- and dicyano-functionalized iron(II) macrobicycles were obtained for the first time by the reaction of iron(II) diiodoclathrochelate precursor with copper(I) cyanide–triphenylphosphine complex under mild conditions. The target dinitrile clathrochelate is a minor product of this reaction, whereas the major product contains only one cyano group. The clathrochelates obtained were characterized using elemental analysis, 1H and 13C{1H} NMR, IR and UV-vis spectroscopy, MALDI-TOF spectrometry and X-ray diffraction crystallography. The geometry of their FeN6-coordination polyhedra is intermediate between a trigonal prism (TP) and a trigonal antiprism (TAP); the distortion angles, φ, are 22.6–24.7°. In the molecule of the precursor, the Fe–N distances are close, whereas in the mononitrile macrobicycles those for their functionalized chelate fragments are substantially smaller than the corresponding distances in the α-benzyldioximate moieties. The heights, h, of the TP–TAP coordination polyhedra and the average bite angles, α, (2.33 Å and 39°, respectively) are the same for the X-rayed clathrochelates. The UV-vis spectra indicate a dramatic redistribution of the electron density in the π-conjugated clathrochelate framework caused by functionalization with inherent nitrile substituents. The proposed mechanism of the dehalogenation–reduction reaction of iron(II) diiodoclathrochelate resulting in substitution of their iodine atoms by a cyano group and hydrogen atom includes the anion-radical hydrodehalogenation of this precursor with acetonitrile as a source of hydrogen atom. Then, the monomethinemonoiodine macrobicyclic product underwent a substitution with a cyano group only. The copper(I) cyanide–triphenylphosphine–acetonitrile system is proposed as a tool for the synthesis of nitrile derivatives of electron-withdrawing heterocycles starting from their halogen-containing precursors.
You have access to this article
Please wait while we load your content...
Something went wrong. Try again?