Disodium tetracarbonylferrate is the
organoiron compound with the formula Na
2 e(CO)4 It is always used as a solvate, e.g., with
tetrahydrofuran or
dimethoxyethane, which bind to the sodium cation.
An
oxygen-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
James P. Collman (born 1932) is an American chemist who is the George A. and Hilda M. Daubert Professor of Chemistry, emeritus at Stanford University. Collman's research focused on organometallic bioinorganic chemistry. Collman is a member of t ...
, 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
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...
was originally generated in situ by reducing
iron pentacarbonyl with sodium amalgam.
Modern synthesis use
sodium naphthalene 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 aldehydes from alkyl halides.[
:Na2 e(CO)4 + RBr → Na Fe(CO)4 + NaBr
This solution is then treated sequentially with PPh3 and then ]acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...
to give the aldehyde, RCHO.
Disodium tetracarbonylferrate can be used to convert acid chlorides to aldehydes. This reaction proceeds via the intermediacy of iron acyl complex.
:Na2 e(CO)4 + RCOCl → Na C(O)Fe(CO)4 + NaCl
:Na C(O)Fe(CO)4 + HCl HCL may refer to:
Science and medicine
* Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia
* Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development
* Hollow-cathode lamp, a spe ...
→ RCHO + "Fe(CO)4" + NaCl
Disodium tetracarbonylferrate reacts with alkyl halides (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
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...
and acid halides:
:Na Fe(CO)4 + O2, H+ →→ RCO2H + Fe...
:Na Fe(CO)4 + 2 X2 → RC(O)X + FeX2 + 3 CO + NaX
References
Further reading
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{{iron compounds
Carbonyl complexes
Iron complexes
Sodium compounds
Ferrates