Ferrocene

Description

The synthesis of ferrocene, an organometallic iron complex, has become a very popular experiment for inorganic laboratory courses.

Description

Ferrocene, a metallocene, is a bright orangesalt-like crystals from alcohol with a camphor odor.Molecular weight = 186.05; Boiling point = 249 C (sublimes); Freezing/Melting point = 173 C. Decomposes at465 C. Hazard Identification (based on NFPA-704 MRating System): Health 2, Flammability 2, Reactivity 1.Insoluble in water.

Chemical properties

Orange, crystalline solid; camphor-like odor. Insoluble in water; soluble in benzene, ether, and alcohol. Iron content 29.4–30.6%.

Chemical properties

Ferrocene, a metallocene, is a bright orange salt-like crystals from alcohol. Camphor odor.

Physical properties

Orange crystals; camphor-like odor; melts at 172.5°C; vaporizes at 249°C; sublimes above 100°C; thermally stable above 500°C; insoluble in water; soluble in alcohol, ether and benzene; also soluble in dilute nitric acid and concentrated sulfuric acid forming a deep red solution that fluoresces.

The Uses of Ferrocene

Ferrocene is used as a catalyst for vulcanization, acceleration, and polymerization, as a chemical intermediate for polymeric compounds such as high temperature polymers, as an antiknock additive for gasoline, as a coating for missiles and satellites, and as a high-temperature lubricant.

The Uses of Ferrocene

Antiknock additive for gasoline; catalyst.

The Uses of Ferrocene

In ultraviolet stabilizers and smoke depressants for polymers; to increase the burn rate of rocket propellants; to prevent erosion of space capsule shields; to improve the viscosity of lubricants; to catalyze polymerization reactions; to catalyze combustion; some derivatives used as hematinic agents

What are the applications of Application

Ferrocene is a source of ferrocene derivatives; the derived ferrocenium salts find use as mild oxidants

Definition

A coordination compound of ferrous iron and two molecules of cyclopentadiene in which the organic portions have typically aromatic chemical properties. Its activity is intermediate between phenol and anisole. The first compound shown to have the “sandwich

Definition

ferrocene: An orange-red crystallinesolid, Fe(C₅H₅)₂; m.p. 173°C. Itcan be made by adding the ioniccompound Na₊C₅H₅^- (cyclopentadienylsodium, made from sodium andcyclopentadiene) to iron(III) chloride.In ferrocene, the two rings are parallel,with the iron ion sandwiched betweenthem (hence the namesandwich compound: see formula).The bonding is between pi orbitalson the rings and d-orbitals on theFe²⁺ ion. The compound can undergoelectrophilic substitution on theC₅H₅rings (they have some aromatic character).It can also be oxidized to theblue ion (C₅H₅)₂Fe⁺. Ferrocene is the first of a class of similar complexescalled sandwich compounds. Its systematicname is di-π-cyclopentadienyliron(II).

Production Methods

Ferrocene is produced from the reaction of cyclopentadiene with reduced iron in the presence of metal oxides. There is also a two-stage production process in which produced iron (II)oxide (stage 1) is reacted with cyclopentadiene.

Preparation

Dicyclopentadienyliron may be obtained in a single-step synthetic route by heating cyclopentadiene with iron or iron pentacarbonyl at 300°C:
2C₅H₅ + Fe → (C₅H₅)₂Fe
Also, it can be prepared by the reaction of iron(II) chloride with cyclopentadiene in the presence of an alkyl amine or a similar base.
Another convenient method of preparing this π-complex of iron is a twostep process in which the first step involves preparation of cyclopentadienyl Grignard reagent, such as 2,4-cyclopentadienylmagnesium bromide C5H5MgBr which may then be combined with ferric chloride to yield dicyclopentadienyl iron:
3C₅H₅MgBr + FeCl₃ → (C₅H₅)₂Fe + 3MgBrCl
Another general method of preparation involves the reaction of cyclopentadiene with sodium metal or sodium hydride in tetrahydrofuran (THF). Addition of iron(II) chloride to this solution forms the complex dicyclopentadienyliron:
2C₅H₆ + 2Na → 2C₅H₅ˉ + 2Na+ + H₂
In 3:2 molar ratio of cyclopentadiene to sodium cyclopentene is obtained along with cyclopentadienidide (C₅H₅ˉ ) anion:
3C₅H₆ + 2Na → 2C5H5¯ + 2Na+ + C₅H₈
FeCl₂ + 2C5H₆Na → (C5H5)₂Fe + 2NaCl

General Description

Orange crystalline solid or orange-yellow powder. Sublimes above 212°F. Camphor odor.

Air & Water Reactions

Sensitive to prolonged exposure to air and may be sensitive to light. Insoluble in water.

Reactivity Profile

Ferrocene reacts violently with tetranitromethane. . Contact of tetranitromethane with Ferrocene under various conditions leads to violent explosion, [Trans. Met. Chem., 1979, 4, 207-208].

Hazard

Moderate fire risk. Evolves toxic products on decomposition and heating.

Health Hazard

Dicyclopentadienyl iron causes changes in blood parameters and hepatic cirrhosis.
The toxicological properties of dicyclopentadienyl iron have not been extensively investigated. However, it has been used as a preventive and therapeutic iron deficiency drug, and its utilization is listed as tolerable.

Fire Hazard

Flash point data for Ferrocene are not available. Ferrocene is probably combustible.

Flammability and Explosibility

Highly flammable

Safety Profile

Poison by intraperitoneal and intravenous routes. Moderately toxic by ingestion. Questionable carcinogen with experimental tumorigenic data. Mutation data reported. Flammable; reacts violently with NH4ClO4. When heated to decomposition it emits acrid smoke and irritating fumes.

Potential Exposure

Used as additive in fuel oil; antiknock agent in gasoline fuel; used in making rubber, silicone resins, high-temperature polymers and lubricants; interme diate for high-temperature polymers; as a smoke suppres sant and catalyst

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.

Carcinogenicity

Ferrocene was administered by intramuscular injection at a dose of 5175 mg/kg/2 years. By the criterion established by the Registry of Toxic Effects of Chemical Substances (RTECS), ferrocene was an equivocal tumorigenic agent and tumors were most evident at the site of multiple injections.

storage

Color Code—Red: Flammability Hazard: Store ina flammable materials storage area. Prior to working withthis chemical you should be trained on its proper handlingand storage. Store in tightly closed containers in a cool,well-ventilated area away from oxidizers, ammonium perchlorate, tetranitromethane, mercury(II) nitrate, and heat.Sources of ignition, such as smoking and open flames, areprohibited where this chemical is used, handled, or stored ina manner that could create a potential fire or explosionhazard.

Shipping

UN1325 Flammable solids, organic, n.o.s., Hazard Class: 4.1; Labels: 4.1-Flammable solid.

Purification Methods

Purify it by crystallisation from pentane or cyclohexane (also *C6H6 or MeOH can be used). It is moderately soluble in Et2O and sublimes readily above 100o. Crystallisation from EtOH gave material m 172.5-173o. [Wilkinson Org Synth Coll Vol IV 473 1963, Miller J Chem Soc 632 1952.] It has also been crystallised from methanol and sublimed in vacuo. [Saltiel et al. J Am Chem Soc 109 1209 1987, Beilstein 16 IV 1783.]

Structure and conformation

X-ray diffraction studies show that in crystalline ferrocene (and in its substituted derivatives) the iron atom is "sandwiched" between the two cyclopentadienyl rings, these rings having the staggered configuration relative to each other (Fig. 16). The rings are parallel plane regular pentagons, all the C-C and Fe-C distances being equal. Electron diffraction studies show, however, that ferrocene has the eclipsed configuration in the vapour state.

Incompatibilities

Violent reaction with ammonium per chlorate, tetranitromethane, mercury(II) nitrate. Incompa tible with oxidizers (chlorates, nitrates, peroxides, perman ganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides.
Peroxomonosulfuric acid. Decomposes @≧465 ℃.