A thermogravimetric, single crystal X-ray, and spectroscopic study of several iron (III) halide adducts with crown ethers

• Published in: Inorganica Chimica Acta 1995-11, Vol.239 (1), p.67-75
• Main Authors: Russo, Umberto, Zarli, Bruno, Favero, Giancarlo, Valle, Giovanni, Long, Gary J.
• Format: Article
• Language: English
• Subjects: Crown ether complexes; Crystal structures; Iron complexes; Mössbauer spectroscopy; Thermogravimetry
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/0020-1693(95)04714-X

The interaction of iron(III) halides with 18-crown-6 or 15-crown-5 ethers has led to the isolation of several complexes, two of which, [FeCl 3(H 2O) 2] (15-crown-5) and H(FeBr 4) (15-crown-5) 2(H 2O) 2, yielded crystals suitable for single crystal X-ray structural analysis. The chloro complex crystallizes in the monoclinic P2 1 (No. 4) space group with Z = 2, a = 8.574(1), b = 13.714(2), c = 8.223(1) A ̊ , β = 107.9 (1)°. The crystals contain trigonal bipyramidal [FeCl 3(H 2O) 2] moieties hydrogen bonded to a partially disordered 15-crown-5 ether to form a polymeric chain oriented along the crystallographic c-axis. The bromo complex crystallizes in the cubic Fd 3 (No. 203) space group with Z = 8, a = 19.500(2) A ̊ . The compound contains tetrahedral FeBr 4 − anions which have no bonding interaction with the 15-crown-5 ether, which simply acts as a dielectric medium to separate the anions. A study of the thermal decomposition of the compounds was performed by thermogravimetric analysis. IR and Mössbauer spectral measurements indicate that the decomposition products are water, acetaldehyde, dioxane, chlorine or bromine, carbon dioxide, carbon monoxide, and mixtures of hydrated iron(II) halides and iron oxides.