Tetrakis(methylammonium) hexachloroferrate(III) chloride is a chemical compound with the formula (CH<sub>3</sub>NH<sub>3</sub>)<sub>4</sub>[FeCl<sub>6</sub>]Cl.
The compound has the form of hygroscopic orange crystals. The hexachloroferrate(III) anion is a coordination complex centred on an iron atom in the +3 oxidation state that is covalently bound to six chloride atoms arranged octahedrally around it. Interstitial chloride anions are each surrounded by four methylammonium cations, with hydrogen bond-like links between the ammonium cations and the ligands of the hexachloroferrate(III) moieties. Each [(CH<sub>3</sub>NH<sub>3</sub>)<sub>4</sub>Cl]<sup>3+</sup> unit balances a [FeCl<sub>6</sub>]<sup>3âÂÂ</sup>, analogous to how hexachloroferrate(III) forms stable compounds with various large triply-cationic atoms and other triply-cationic complexes.
The compound is synthesised by reacting methylammonium chloride, CH<sub>3</sub>NH<sub>3</sub>Cl, with anhydrous iron(III) chloride and adding hydrochloric acid with heating. Crystals of the product, which precipitate as the solvent evaporates, are collected and dried using vacuum desiccation.
There is a series of bands from 3129 to 2830 cm<sup>âÂÂ1</sup> that represent stretching modes of the nitrogenâÂÂhydrogen bonds. In addition, a distinct peak is found at 2517 cm<sup>âÂÂ1</sup>, whereas the corresponding signal for methylammonium chloride is at 2476 cm<sup>âÂÂ1</sup>. The 31 cm<sup>âÂÂ1</sup> shift is due to the coordination of an ammonium hydrogen with the hexachloroferrate(III).