Iron(II) chloride 1558629 217707719 2008-06-07T08:11:20Z LordAnubisBOT 2572294 robot Modifying: [[ru:Хлорид железа (II)]] {{Chembox new | Name = Iron(II) chloride | IUPACName = Iron(II) chloride<br /> | OtherNames = Ferrous chloride,<br />Rokühnite (dihydrate) | Section1 = {{Chembox Identifiers | CASOther ={{CASREF|CAS=7758-94-3}} (''anhydr.'')<br />{{CASREF|CAS=13478-10-9}} (tetrahydrate) | EINECS = }} | Section2 = {{Chembox Properties | Formula = FeCl<sub>2</sub> | MolarMass = 126.751 g/mol (anhydrous)<br />198.8102 g/mol ([[tetrahydrate]]) | Appearance = anhydrous: tan<br />tetrahydrate: pale green | Density = 3.16 g/mL g/cm<sup>3</sup>, solid | Solvent = [[THF]] | SolubleOther = soluble | Solubility = 64.4 g/100 mL (10°C),<br />105.7 g/100 mL (100°C) | Solvent2 = [[ethanol]] | SolubleOther2 = 100 g/100 mL | MeltingPt = 677 °C }} | Section3 = {{Chembox Structure | Coordination = octahedral at Fe | CrystalStruct = [[Monoclinic]] }} | Section8 = {{Chembox Related | OtherCpds = [[Cobalt(II) chloride]]<br />[[Manganese(II) chloride]]<br />[[Copper(II) chloride]] }} }} '''Iron(II) chloride''', also known as '''ferrous chloride''', is the [[chemical compound]] of formula FeCl<sub>2</sub>. It has a high melting point, [[paramagnetic]] solid, usually obtained as an off-white solid. FeCl<sub>2</sub> [[crystallizes]] from water as the greenish [[Water of crystallization|tetrahydrate]], which is how the salt is most commonly encountered in commerce and the laboratory. ==Synthesis== A classical synthesis of metal halides involves the action of hydrogen chloride on the metal. ::[[iron|Fe]] + 2 HCl → FeCl<sub>2</sub> + [[hydrogen|H<sub>2</sub>]] For FeCl<sub>2</sub>, the synthesis is more conveniently conducted using a [[methanol]] solution of concentrated [[hydrochloric acid]]. Reaction of this with iron gives the methanol solvate [Fe(MeOH)<sub>6</sub>]Cl<sub>2</sub>, which upon heating in a vacuum at ''ca.'' 160 °C gives pure FeCl<sub>2</sub>.<ref>G. Winter, Inorganic Synthesis, 1973, volume 14, pp. 101-104.</ref> FeBr<sub>2</sub> and FeI<sub>2</sub> can be prepared analogously. An alternative laboratory synthesis of FeCl<sub>2</sub> entails the reaction of [[ferric chloride|FeCl<sub>3</sub>]] with [[chlorobenzene]]:<ref>P. Kovacic and N. O. Brace, Inorganic Synthesis, 1960, volume 6, p. 172.</ref><ref> P. Kovacic and N. O. Brace, J. Am. Chem. Soc., 1954, volume 76, p. 5491.</ref> ::2FeCl<sub>3</sub> + C<sub>6</sub>H<sub>5</sub>Cl → 2FeCl<sub>2</sub> + C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> + [[hydrogen chloride|HCl]] FeCl<sub>2</sub> prepared in this way exhibits convenient solubility in [[tetrahydrofuran]], a common solvent for chemical reactions. For one of his two classic syntheses of [[ferrocene]], [[Geoffrey Wilkinson|Wilkinson]] generated FeCl<sub>2</sub> by heating FeCl<sub>3</sub> with iron powder.<ref>G. Wilkinson, "Ferrocene", Organic Syntheses, Coll. Vol. 4, p.473 (1963); Vol. 36, p.31 (1956).</ref> ==Hydrated and aqueous ferrous chloride== FeCl<sub>2</sub> forms complexes with many ligands. Its most common derivative is the hydrate, FeCl<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>. Hydrated forms of ferrous chloride are generated by treatment of wastes from steel production with [[hydrochloric acid]]. Such solutions are designated '''spent acid''', especially when the [[hydrochloric acid]] is not completely consumed. The spent acid requires treatment before its disposal. ==Reactions== FeCl<sub>2</sub> reacts with two molar equivalents of [(C<sub>2</sub>H<sub>5</sub>)<sub>4</sub>N]Cl to give the salt [(C<sub>2</sub>H<sub>5</sub>)<sub>4</sub>N]<sub>2</sub>[FeCl<sub>4</sub>]. Related compounds that can be prepared similarly include the [MnCl<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup>, [MnBr<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup>, [MnI<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup>, [FeBr<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup>, [CoCl<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup>, [CoBr<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup>, [NiCl<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup> and [CuCl<sub>4</sub>]<sup>2<nowiki>&minus;</nowiki></sup> salts.<ref>N. S. Gill & F. B. Taylor, Inorganic Synthesis, 1967, volume 9, pp. 136-142.</ref> ==References== <references/> ==See also== * [[Hydrochloric acid]] * [[Iron(III) chloride]] * [[Iron(II) sulfate]] [[Category:Chlorides]] [[Category:Inorganic compounds]] [[Category:Iron compounds]] [[Category:Metal halides]] [[ar:كلوريد حديد ثنائي]] [[de:Eisen(II)-chlorid]] [[es:Cloruro de hierro (II)]] [[fr:Chlorure de fer (II)]] [[ja:塩化鉄(II)]] [[pl:Chlorek żelaza(II)]] [[pt:Cloreto de ferro (II)]] [[ru:Хлорид железа (II)]] [[zh:氯化亚铁]]