Triruthenium dodecacarbonyl
Encyclopedia
Triruthenium dodecacarbonyl is the chemical compound
with the formula Ru3(CO)12. This orange-colored metal carbonyl cluster
is a precursor to other organoruthenium compounds.
, consisting of an equilateral triangle of Ru atoms, each of which bears two axial and two equatorial CO ligands. Os3(CO)12
has the same structure, whereas Fe3(CO)12
is different, with two bridging CO ligands, resulting in C2v symmetry.
Ru3(CO)12 is prepared by treating solutions of ruthenium trichloride
with carbon monoxide
, usually under high pressure. The stoichiometry of the reaction is uncertain, one possibility being the following:
The instability of Ru(CO)5 contrasts with the robustness of the corresponding Fe(CO)5
. The condensation
of Ru(CO)5 into Ru3(CO)12 proceeds via initial, rate-limiting loss of CO to give the unstable, coordinatively unsaturated species Ru(CO)4. This tetracarbonyl binds Ru(CO)5, initiating the condensation.
Upon warming under a pressure of hydrogen
, Ru3(CO)12 converts to the tetrahedral cluster H4Ru4(CO)12. Ru3(CO)12 undergoes substitution reactions with Lewis bases:
where L is a tertiary phosphine or an isocyanide
.
ligands. These include Ru6C(CO)17 and Ru5C(CO)15. Anionic carbido clusters are also known, including [Ru5C(CO)14]2- and the bioctahedral
cluster [Ru10C2(CO)24]2-.
Ru3(CO)12 -derived carbido compounds have been used to synthesize nanoparticles for catalysis. These particles consist of 6-7 atoms and thus are all surface, resulting in extraordinary activity.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the formula Ru3(CO)12. This orange-colored metal carbonyl cluster
Cluster chemistry
In chemistry, a cluster is an ensemble of bound atoms intermediate in size between a molecule and a bulk solid. Clusters exist of diverse stoichiometries and nuclearities. For example, carbon and boron atoms form fullerene and borane clusters, respectively. Transition metals and main group...
is a precursor to other organoruthenium compounds.
Structure and synthesis
The cluster has D3h symmetrySymmetry group
The symmetry group of an object is the group of all isometries under which it is invariant with composition as the operation...
, consisting of an equilateral triangle of Ru atoms, each of which bears two axial and two equatorial CO ligands. Os3(CO)12
Triosmium dodecacarbonyl
Triosmium dodecacarbonyl is a chemical compound with the formula Os312. This yellow-colored metal carbonyl cluster is an important precursor to organo-osmium compounds...
has the same structure, whereas Fe3(CO)12
Triiron dodecacarbonyl
Triiron dodecarbonyl is the chemical compound with the formula Fe312. It was one of the first metal carbonyl clusters synthesized. It is a more reactive source of iron than is iron pentacarbonyl.-General properties:...
is different, with two bridging CO ligands, resulting in C2v symmetry.
Ru3(CO)12 is prepared by treating solutions of ruthenium trichloride
Ruthenium(III) chloride
Ruthenium chloride is the chemical compound with the formula RuCl3. "Ruthenium chloride" more commonly refers to the hydrate RuCl3·xH2O. Both the anhydrous and hydrated species are dark brown or black solids...
with carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
, usually under high pressure. The stoichiometry of the reaction is uncertain, one possibility being the following:
- 6 RuCl3 + 33 CO + 18 CH3OH → 2 Ru3(CO)12 + 9 CO(OCH3)2 + 18 HCl
Reactions
The chemical properties of Ru3(CO)12 have been widely studied, and the cluster has been converted to hundreds of derivatives. High pressures of CO convert the cluster to the monomeric pentacarbonyl, which reverts back to the parent cluster upon standing.- Ru3(CO)12 + 3 CO
3 Ru(CO)5 Keq = 3.3 x 10-7 mol dm–3 at room temperature
The instability of Ru(CO)5 contrasts with the robustness of the corresponding 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...
. The condensation
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....
of Ru(CO)5 into Ru3(CO)12 proceeds via initial, rate-limiting loss of CO to give the unstable, coordinatively unsaturated species Ru(CO)4. This tetracarbonyl binds Ru(CO)5, initiating the condensation.
Upon warming under a pressure of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
, Ru3(CO)12 converts to the tetrahedral cluster H4Ru4(CO)12. Ru3(CO)12 undergoes substitution reactions with Lewis bases:
- Ru3(CO)12 + n L → Ru3(CO)12-nLn + n CO (n = 1, 2, or 3)
where L is a tertiary phosphine or an isocyanide
Isocyanide
An isocyanide is an organic compound with the functional group -N≡C. It is the isomer of the related cyanide , hence the prefix iso....
.
Ru-carbido clusters
At high temperatures, Ru3(CO)12 converts to a series of clusters that contain interstitial carbidoCarbide
In chemistry, a carbide is a compound composed of carbon and a less electronegative element. Carbides can be generally classified by chemical bonding type as follows: salt-like, covalent compounds, interstitial compounds, and "intermediate" transition metal carbides...
ligands. These include Ru6C(CO)17 and Ru5C(CO)15. Anionic carbido clusters are also known, including [Ru5C(CO)14]2- and the bioctahedral
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...
cluster [Ru10C2(CO)24]2-.
Ru3(CO)12 -derived carbido compounds have been used to synthesize nanoparticles for catalysis. These particles consist of 6-7 atoms and thus are all surface, resulting in extraordinary activity.