Extension of an Encapsulating Macrobicyclic Ligand Using the Palladium-Catalyzed Suzuki–Miyaura Reaction of a Diiodoclathrochelate Iron(II) Tris-Glyoximate with Reactive Halogen Atoms in Its Apical Substituents

Abstract

The ability to extend the apical substituents at a macrobicyclic tris-glyoximate framework using a palladium-catalyzed Suzuki–Miyaura C–C-cross-coupling was tested. The reaction of an iron(II) diiodoclathrochelate with phenylboronic acid was successfully performed in toluene using the catalytic system Pd(CH3COO)2/SPhos and CsF as inorganic base. The reflux at 110°C gave a macrobicyclic iron(II) complex with two apical biphenyl substituents, characterized using the spectral methods and by the single crystal X-ray diffraction. Asymmetric unit of its crystal consists of two symmetrically independent clathrochelate molecules. Their FeN6-coordination polyhedra with heights h of 2.37 A, Fe–N distances of 1.903(3)–1.916(2) A, and the bite (chelate) angles α of 78.4°–78.6° possess a distorted trigonal prismatic–trigonal-antiprismatic geometry with the distortion angles φ of 18.5° and 18.0°, respectively; the encapsulated iron(II) ion is situated almost in their centers. The crystal packing is mainly governed by the intermolecular hydrophobic H···H, H···C, and C···C interactions and by the H···O, and H···N hydrogen bonds as well.