Methylthioirontricarbonyl dimer, also known as methanethiolatoirontricarbonyl dimer, is an
organometallic compound
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...
with the formula Fe
2(SCH
3)
2(CO)
6. It is a red volatile solid that is classified as a
transition metal thiolate complex. It exists as air-stable red crystals with two
isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Iso ...
s, where the methyl groups are either ''anti'' (isomer A) or ''syn'' (isomer B) with respect to each other.
Synthesis
It was first synthesized 1940 with the discovery of isomers in 1962. Synthesis involves treating
triiron dodecacarbonyl
Triiron dodecarbonyl is the organoiron compound with the formula Fe3(CO)12. It is a dark green solid that sublimes under vacuum. It is soluble in nonpolar organic solvents to give intensely green solutions. Most low-nuclearity clusters are pale ...
with
dimethyl disulfide
Dimethyl disulfide (DMDS) is an organic chemical compound with the molecular formula which is the simplest disulfide. It is a flammable liquid with an unpleasant, garlic-like odor.
Occurrence
Dimethyl disulfide is a widespread natural odorifero ...
:
:2 Fe
3(CO)
12 + 3 (CH
3)
2S
2 → 3
e(CO)3SCH3sub>2 + 6 CO
It can be purified by
recrystallization or by
sublimation. The isomers can be separated by
chromatography
In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system (a ...
.
Structure
The methylthioirontricarbonyl dimer is a
butterfly cluster compound, consisting of two iron atoms with distorted
square pyramidal
In molecular geometry, square pyramidal geometry describes the shape of certain Chemical compound, compounds with the formula where L is a ligand. If the ligand atoms were connected, the resulting shape would be that of a Square pyramid, pyram ...
coordination geometry. The geometry is
octahedral
In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...
if the Fe-Fe bond is included. Each iron has three terminal carbon monoxide ligands and two bridging methylthiolate ligands. The Fe-Fe distance is 2.537 Å with an average Fe-S bond length of 2.259 Å. The average Fe-S-Fe bond angle is relatively small at 68.33°. Three isomers are possible but only the diequatorial and axial-equatorial isomers are seen. The diaxial isomer is disfavored due to
steric hindrance
Steric effects arise from the spatial arrangement of atoms. When atoms come close together there is a rise in the energy of the molecule. Steric effects are nonbonding interactions that influence the shape ( conformation) and reactivity of ions ...
.
The structurally related compound
e(CO)3Ssub>2 has idealized C
2v symmetry
Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definit ...
.
References
{{Iron compounds
Carbonyl complexes
Iron compounds
Thiolates