First example of perfluoroalkylation of a quasi-aromatic encapsulating ligand: 2,5-Dithiahexane-assisted reaction of the iron(II) diiodoclathrochelate with trifluoromethylcopper(I)

Abstract

Perfluoroalkylation of an iron(II) diiodoclathrochelate precursor with trifluoromethyltrimethylsilane and copper(I) iodide in THF using 2,5-dithiahexane as a co-ligand and potassium fluoride as the base afforded mono- and bis-trifluoromethylated cage complexes in moderate yields. These complexes were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV–Vis, 1 H, 11 B, 19 F and 13 C{ 1 H} NMR spectroscopies, and by X-ray crystallography. The geometry of their FeN 6 -coordination polyhedra is intermediate between a trigonal prism and a trigonal antiprism, the encapsulated iron(II) ions are located almost in the center of these polyhedra. The average Fe–N distances (av. 1.91 Å), the distortion φ angles (approximately 26°) and the heights h of the coordination polyhedra (2.31 Å) are characteristic of the boron-capped iron(II) clathrochelates. The anodic ranges of the cyclic voltammograms for the trifluoromethylated iron(II) clathrochelates contain one-electron waves of an irreversible oxidation assigned to the metal-centered redox process Fe 2 +/3 + , while those in their cathodic ranges were assigned to the Fe 2 +/+ reduction. The ribbed functionalization of the iron clathrochelates with trifluoromethyl substituent(s) destabilizes both their oxidized and reduced forms. The perfluoroalkylation of iron(II) diiodoclathrochelate precursor with (CF 3 )Cu afforded mono- and bis-trifluoromethylated cage complexes in moderate yields, which were characterized using spectral methods and X-ray diffraction. According to cyclic voltammetry data, the ribbed functionalization of the iron clathrochelates with trifluoromethyl substituent(s) destabilizes both their oxidized and reduced forms. • The cage complexes with inherent trifluoromethyl group(s) were first obtained. • Reaction of iron diiodoclathrochelate with (CF3)Cu gave trifluoromethylated complexes. • Trifluoromethylation of iron complex destabilizes its oxidized and reduced forms. • The synthetic pathways to the perfluoroalkylated metal clathrochelates were developed.