title: Synthesis and structure of the first clathrochelate iron(II) tris-dioximates with inherent nitrile substituent(s) and new dehalogenation--reduction reaction at a quasi-aromatic macrobicyclic framework.
abstract: 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, (1)H and (13)C{(1)H} NMR, IR and UV-vis spectroscopy, MALDI-TOF spectrometry and X-ray diffraction crystallography. The geometry of their FeN(6)-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.
authors.affiliation: A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 119991, Moscow, Russian Federation. voloshin@ineos.ac.ru
authors.forename: Yan Z
authors.initials: YZ
authors.lastname: Voloshin
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Belov
authors.forename: Oleg A
authors.initials: OA
authors.lastname: Varzatskii
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Shul'ga
authors.forename: Pavel A
authors.initials: PA
authors.lastname: Stuzhin
authors.forename: Zoya A
authors.initials: ZA
authors.lastname: Starikova
authors.forename: Ekaterina G
authors.initials: EG
authors.lastname: Lebed
authors.forename: Yurii N
authors.initials: YN
authors.lastname: Bubnov