Disodium tetracarbonylferrate is the

organoiron compound Organoiron chemistry is the chemistry of iron compounds containing a carbon-to-iron chemical bond. Organoiron compounds are relevant in organic synthesis as reagents such as iron pentacarbonyl, diiron nonacarbonyl and disodium tetracarbonylferrat ...

with the formula Na₂ e(CO)₄ It is always used as a solvate, e.g., with

tetrahydrofuran Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...

dimethoxyethane Dimethoxyethane, also known as glyme, monoglyme, dimethyl glycol, ethylene glycol dimethyl ether, dimethyl cellosolve, and DME, is a colorless, aprotic, and liquid ether that is used as a solvent, especially in batteries. Dimethoxyethane is mi ...

, which bind to the sodium cation. An

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

-sensitive colourless solid, it is a reagent in organometallic and organic chemical research. The dioxane solvated sodium salt is known as Collman's reagent, in recognition of James P. Collman, an early popularizer of its use.

Structure

The dianion e(CO)₄sup>2− is isoelectronic with Ni(CO)₄. The iron center is tetrahedral, with Na⁺---OCFe interactions. It is commonly used with

dioxane 1,4-Dioxane () is a heterocyclic organic compound, classified as an ether. It is a colorless liquid with a faint sweet odor similar to that of diethyl ether. The compound is often called simply dioxane because the other dioxane isomers ( 1,2- ...

complexed to the sodium cation.

Synthesis

The reagent was originally generated in situ by reducing

iron pentacarbonyl Iron pentacarbonyl, also known as iron carbonyl, is the compound with formula . Under standard conditions Fe( CO)5 is a free-flowing, straw-colored liquid with a pungent odour. Older samples appear darker. This compound is a common precursor to ...

with sodium amalgam. Modern synthesis use

sodium naphthalene Sodium naphthalene is an organic salt with the chemical formula Na+. In the research laboratory, it is used as a reductant in the synthesis of organic, organometallic, and inorganic chemistry. It is usually generated in situ. When isolated, it ...

or sodium benzophenone ketyls as the reducants: :Fe(CO)₅ + 2 Na → Na₂ e(CO)₄ + CO When a deficiency of sodium is used, the reduction affords deep yellow octacarbonyl ''di''ferrate: :2 Fe(CO)₅ + 2 Na → Na₂ e₂(CO)₈ + 2 CO Some specialized methods do not start with iron carbonyl.

Reactions

It is used to synthesise

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

s from alkyl halides. The reagent was originally described for the conversion of primary alkyl bromides to the corresponding aldehydes in a two-step, "one-pot" reaction: :Na₂ e(CO)₄ + RBr → Na Fe(CO)₄ + NaBr This solution is then treated sequentially with PPh₃ and then acetic acid to give the aldehyde, RCHO. Disodium tetracarbonylferrate can be used to convert

acid chloride In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example o ...

s to aldehydes. This reaction proceeds via the intermediacy of iron

acyl In chemistry, an acyl group is a moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an alkyl group (). In organic chemistry, the acyl group (IUPAC ...

complex. :Na₂ e(CO)₄ + RCOCl → Na C(O)Fe(CO)₄ + NaCl :Na C(O)Fe(CO)₄ + HCl → RCHO + "Fe(CO)₄" + NaCl Disodium tetracarbonylferrate reacts with

alkyl halides The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely us ...

(RX) to produce alkyl complexes: :Na₂ e(CO)₄ + RX → Na Fe(CO)₄ + NaX Such iron alkyls can be converted to the corresponding carboxylic acid and

acid halide In organic chemistry, an acyl halide (also known as an acid halide) is a chemical compound derived from an oxoacid by replacing a hydroxyl group () with a halide group (, where X is a halogen). If the acid is a carboxylic acid (), the compound c ...

s: :Na Fe(CO)₄ + O₂, H⁺ →→ RCO₂H + Fe... :Na Fe(CO)₄ + 2 X₂ → RC(O)X + FeX₂ + 3 CO + NaX

Structure

Synthesis

Reactions

References

Further reading