Tris(triphenylphosphine)ruthenium(II) chloride
[CAS# 15529-49-4]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic ruthenium
• Name: Tris(triphenylphosphine)ruthenium(II) chloride
• Synonyms: Dichlorotris(triphenylphosphine)ruthenium(II)
• Molecular Formula: C₅₄H₄₅Cl₂P₃Ru
• Molecular Weight: 958.84
• CAS Registry Number: 15529-49-4
• EC Number: 239-569-7
• SMILES: C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.Cl[Ru]Cl

Properties

• Melting point: 132 - 134 °C (Expl.)
• Solubility: Very slightly soluble ( acetone, alcohol, chloroform, ethyl acetate, and toluene) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H312-H332
• Safety Statements: P261-P264-P270-P271-P280-P301+P317-P302+P352-P304+P340-P317-P321-P330-P362+P364-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H302

Discovery and Applications

Tris(triphenylphosphine)ruthenium(II) chloride is a coordination complex with the formula RuCl₂(PPh₃)₃, where Ru represents ruthenium in the +2 oxidation state, Cl is chloride, and PPh₃ stands for triphenylphosphine ligands. The complex is characterized by a ruthenium center coordinated to two chloride ions and three triphenylphosphine molecules, resulting in an octahedral geometry typical for d⁶ metal centers.

This complex is typically synthesized by reacting ruthenium(III) chloride hydrate or ruthenium(III) chloride with an excess of triphenylphosphine under reflux in an appropriate solvent such as ethanol, acetone, or toluene. During the reaction, ruthenium is reduced from the +3 to the +2 oxidation state, while triphenylphosphine acts as both ligand and reducing agent. The product is usually isolated as red or dark red crystals.

Tris(triphenylphosphine)ruthenium(II) chloride is an important precursor in homogeneous catalysis and organometallic synthesis. Its stability and solubility in common organic solvents make it a versatile starting material for preparing other ruthenium complexes by ligand substitution reactions. For example, one or more of the triphenylphosphine ligands can be replaced with nitrogen-based ligands, carbonyls, or olefins to tailor the catalytic and electronic properties of the metal center.

In catalysis, this ruthenium complex is employed in various organic transformations, including hydrogenation, transfer hydrogenation, oxidation, and C–C bond-forming reactions. Its ability to activate molecular hydrogen and other substrates under mild conditions contributes to its widespread use in both academic research and industrial processes. Moreover, it serves as a precursor to catalysts used in asymmetric synthesis, where chiral ligands can be introduced to induce enantioselectivity.

The complex also finds application in the synthesis of organometallic compounds, where it facilitates the formation of Ru–C bonds and participates in catalytic cycles involving oxidative addition, migratory insertion, and reductive elimination steps. These features enable its use in carbonylation, olefin metathesis, and cross-coupling reactions.

From a structural viewpoint, RuCl₂(PPh₃)₃ exhibits octahedral geometry with the chloride ligands positioned cis to each other and the bulky triphenylphosphine ligands occupying the remaining coordination sites. The complex is diamagnetic and diametrically symmetric in solution, which has been confirmed by spectroscopic methods such as NMR and IR spectroscopy.

Handling of tris(triphenylphosphine)ruthenium(II) chloride requires standard laboratory precautions. The compound is generally stable under air but should be stored in a dry, cool place protected from light to prevent degradation. It can be sensitive to moisture and should be handled under inert atmosphere when high purity or reactivity is required.

In summary, tris(triphenylphosphine)ruthenium(II) chloride is a well-defined octahedral ruthenium(II) complex widely used as a catalyst precursor and synthetic intermediate in organometallic and catalytic chemistry. Its versatility, stability, and reactivity make it an essential compound in the development of ruthenium-based catalytic systems and homogeneous catalysis applications.

References

2023. Current State-of-Art in the Guerbet-Type β-Alkylation of Secondary Alcohols with Primary Alcohols Catalyzed by Complexes Based on 3d Metals. Dehydrogenation Reactions with 3d Metals.
DOI: 10.1007/3418_2023_112

2023. Benzothiazole and benzoxazole promoted cleavage of Ru − C(aryl) bond in a four-membered ortho-metalated ruthenium(II) organometallics. Structural Chemistry, 34(2).
DOI: 10.1007/s11224-023-02137-9

2023. Pincer Ru with a single stereogenic identity for highly efficient asymmetric transfer hydrogenation of ketones. Science China Chemistry, 66(4).
DOI: 10.1007/s11426-022-1535-7