Diiron nonacarbonyl
Encyclopedia
Diiron nonacarbonyl is an inorganic compound
with the formula
Fe2(CO)9. This metal carbonyl
is an important reagent in organometallic chemistry
and of occasional use in organic synthesis
. It is a more reactive source of Fe(0) than Fe(CO)5
and less dangerous to handle because it is nonvolatile. This micaceous orange solid is virtually insoluble in all common solvents.
Fe2(CO)9 consists of a pair of Fe(CO)3 centers linked by three bridging CO ligands. The iron atoms are equivalent and octahedral molecular geometry
. Elucidation of the structure of Fe2(CO)9 proved to be challenging because its low solubility inhibits growth of crystals. The Mößbauer spectrum
reveals one quadrupole doublet, consistent with the D3h-symmetric structure.
solution. In these conversions, it is proposed that small amounts of Fe2(CO)9 dissolve according the following reaction:
Cyclobutadieneiron tricarbonyl
is prepared using Fe2(CO)9. Fe2(CO)9 has also been employed in the synthesis of cyclopentadienones via a net [2+3]-cycloaddition
from dibromoketones, known as the Noyori [3+2] reaction.
Low temperature UV/vis photolysis of Fe2(CO)9 yields the Fe2(CO)8 unsaturated complex, producing both CO-bridged and unbridged isomers.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
Fe2(CO)9. This metal carbonyl
Metal carbonyl
Metal carbonyls are coordination complexes of transition metals with carbon monoxide ligands. These complexes may be homoleptic, that is containing only CO ligands, such as nickel carbonyl , but more commonly metal carbonyls contain a mix of ligands, such as Re3Cl...
is an important reagent in organometallic chemistry
Organometallic chemistry
Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...
and of occasional use in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
. It is a more reactive source of Fe(0) than Fe(CO)5
Iron pentacarbonyl
Iron pentacarbonyl, also known as iron carbonyl, is the compound with formula 5. Under standard conditions Fe5 is a free-flowing, straw-colored liquid with a pungent odour. This compound is a common precursor to diverse iron compounds, including many that are useful in organic synthesis. Fe5 is...
and less dangerous to handle because it is nonvolatile. This micaceous orange solid is virtually insoluble in all common solvents.
Synthesis and structure
Following the original method, photolysis of an acetic acid solution of Fe(CO)5 produces Fe2(CO)9 in good yield:- 2 Fe(CO)5 → Fe2(CO)9 + CO
Fe2(CO)9 consists of a pair of Fe(CO)3 centers linked by three bridging CO ligands. The iron atoms are equivalent and octahedral molecular geometry
Octahedral molecular geometry
In chemistry, octahedral molecular geometry describes the shape of compounds where in six atoms or groups of atoms or ligands are symmetrically arranged around a central atom, defining the vertices of an octahedron...
. Elucidation of the structure of Fe2(CO)9 proved to be challenging because its low solubility inhibits growth of crystals. The Mößbauer spectrum
Mössbauer effect
The Mössbauer effect, or recoilless nuclear resonance fluorescence, is a physical phenomenon discovered by Rudolf Mössbauer in 1958. It involves the resonant and recoil-free emission and absorption of γ radiation by atomic nuclei bound in a solid...
reveals one quadrupole doublet, consistent with the D3h-symmetric structure.
Reactions
Fe2(CO)9 is a precursor to compounds of the type Fe(CO)4L and Fe(CO)3(diene). Such syntheses are typically conducted in THFThF
Follicular B helper T cells , are antigen-experienced CD4+ T cells found in the B cell follicles of secondary lymphoid organs such as lymph nodes, spleens and Peyer's patches, and are identified by their constitutive expression of the B cell follicle homing receptor CXCR5...
solution. In these conversions, it is proposed that small amounts of Fe2(CO)9 dissolve according the following reaction:
- Fe2(CO)9 → Fe(CO)5 + Fe(CO)4(THF)
Cyclobutadieneiron tricarbonyl
Cyclobutadieneiron tricarbonyl
Cyclobutadieneiron tricarbonyl or Fe3 is an organometallic complex of cyclobutadiene and an iron metal carbonyl. The chemical compound is used in organic chemistry as a precursor for cyclobutadiene...
is prepared using Fe2(CO)9. Fe2(CO)9 has also been employed in the synthesis of cyclopentadienones via a net [2+3]-cycloaddition
Cycloaddition
A cycloaddition is a pericyclic chemical reaction, in which "two or more unsaturated molecules combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity." The resulting reaction is a cyclization reaction.Cycloadditions are usually described by the...
from dibromoketones, known as the Noyori [3+2] reaction.
Low temperature UV/vis photolysis of Fe2(CO)9 yields the Fe2(CO)8 unsaturated complex, producing both CO-bridged and unbridged isomers.