ruthenium dichloride dimer is the organometallic compound 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....

 [(cymene)RuCl₂]₂. This red-coloured, diamagnetic solid is a reagent

Reagent

A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...

 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 homogeneous catalysis

Homogeneous catalysis

In chemistry, homogeneous catalysis is a sequence of reactions that involve a catalyst in the same phase as the reactants. Most commonly, a homogeneous catalyst is codissolved in a solvent with the reactants.-Acid catalysis:...

.

Preparation and reactions

The dimer is prepared by the reaction of the phellandrene

Phellandrene

Phellandrene is the name for a pair of organic compounds that have a similar molecular structure and similar chemical properties. α-Phellandrene and β-phellandrene are cyclic monoterpenes and are double-bond isomers. In α-phellandrene, both double bonds are endocyclic and in β-phellandrene, one...

 with hydrated ruthenium trichloride. Upon heating, [(cymene)RuCl₂]₂ undergoes exchange with other arene

Arene

Arene or Arênê or Arène may refer to:*an aromatic hydrocarbon*Arene , a genus of marine snails in the family Areneidae*Arene , the wife of Aphareus and mother of Idas and Lynceus in Greek mythology...

s, releasing free p-cymene. This dimeric molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 cleaves easily in the presence of Lewis bases to give monomeric adduct

Adduct

An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...

s:

[(cymene)RuCl₂]₂ + 2 PPh₃

Triphenylphosphine

Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...

  → 2 (cymene)RuCl₂(PPh₃)

Such monomers adopt pseudo-octahedral piano-stool structures.

Treatment of [(cymene)RuCl₂]₂ with the chelating anionic ligand precursor TsDPENH gives (cymene)Ru(TsDPEN-H), a catalyst for asymmetric transfer hydrogenation

Transfer hydrogenation

Transfer hydrogenation is the addition of hydrogen to a molecule from a source other than gaseous H2. It is applied in industry and in organic synthesis, in part because of the inconvenience and expense of using gaseous H2...

.

New catalysts

[(cymene)RuCl₂]₂ is also used to prepare catalysts (by monomerization with dppf) used in borrowing hydrogen

Borrowing hydrogen

Borrowing hydrogen catalysis is an important catalytic concept that is based on the intermediate oxidation of an alcohol substrate to the corresponding aldehyde by the catalyst ; the intermediate aldehyde then reacts with e.g. a secondary amine in a condensation reaction to produce e.g...

 catalysis, a catalytic reaction that is based on the activation of alcohols towards nucleophilic attack.