1,3-Bis-(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorophenyl-methylene)(tricyclohexylphosphine)ruthenium (II)

Synonyms Grubbs 2nd Generation Catalyst; Grubbs Second Generation Catalyst; Grubbs Catalyst; Benzylidene-1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolin-2-ylidene)(tricyclohexylphosphine)dichlororuthenium; GRUBBS II; Grubbs Catalyst

English Synonyms GRUBBS II; Grubbs 2nd; Grubbs catalyst II; Grubbs Gen 2nd; 2nd generation Grubbs catalyst; (1,3-Dimesitylimidazolin-2-ylidene)(tricyclohexylphosphine)ruthenium dichloride; Benzylidene(dichloro)(1,3-dimesityl-2-imidazolidinylidene)ruthenium – tricyclohexylphosphine (1:1); Tricyclohexylphosphine[1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene]ruthenium(IV)dichloride

CAS Number 246047-72-3

EINECS Number 688-322-3

Chemical Formula C₄₆H₆₅Cl₂N₂PRu

Molecular Weight 848.97 / 848.98

InChI InChI=1S/C₂₁H₂₆N₂.C₁₈H₃₃P.C₇H₆.2ClH.Ru/c1-14-9-16(3)20(17(4)10-14)22-7-8-23(13-22)21-18(5)11-15(2)12-19(21)6;1-4-10-16(11-5-1)19(17-12-6-2-7-13-17)18-14-8-3-9-15-18;1-7-5-3-2-4-6-7;;;/h9-12H,7-8H2,1-6H3;16-18H,1-15H2;1-6H;2*1H;/q;;;;;+2/p-2

Flash Point 103 °C

Storage Conditions Store at 2-8°C, protected from light, under nitrogen/argon atmosphere

Sensitivity Sensitive to air and moisture; sensitive to light

Appearance Pink to red-purple crystals or powder; dark red to deep brown solid

Color Brown to deep brown to deep dark red

MDL Number MFCD03453237

Hazard Symbols F (Flammable solid); GHS02

Risk Phrases R11 (Highly flammable); R36/37/38 (Irritating to eyes, respiratory system and skin)

Safety Phrases S26 (In case of contact with eyes, rinse immediately with plenty of water and seek medical advice); S36/37/39 (Wear suitable protective clothing, gloves and eye/face protection)

I. Properties

Grubbs 2nd Generation Catalyst is a ruthenium carbene complex with ruthenium(II) as the central metal. The ligands include: one N-heterocyclic carbene (NHC) ligand (1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene), one tricyclohexylphosphine ligand, two chloride ions, and one benzylidene (carbene) ligand. This catalyst is a pink to red-purple crystal or powder with a melting point of 143.5-148.5 °C. Compared to the first generation, the second generation Grubbs catalyst exhibits higher catalytic activity, better stability, and a broader substrate scope, showing good activity even for sterically hindered or electron-deficient olefins. The catalyst is stable under recommended storage conditions but is sensitive to air and moisture, requiring protection under inert atmosphere.

II. Applications

Grubbs 2nd Generation Catalyst is mainly used for olefin metathesis reactions, including:

In the pharmaceutical industry, it is used for the synthesis of macrocyclic drugs (such as hepatitis C therapeutics) and peptide stapling. In materials science, it is used for the polymerization of functionalized cyclopentenes such as norbornene.

III. Preparation

Grubbs and co-workers reported a direct synthesis method: by introducing a saturated N-heterocyclic carbene (SIMes) ligand into the first generation Grubbs catalyst to replace one of the phosphine ligands, thereby obtaining the second generation catalyst. Specifically, it is usually prepared by reacting the first generation Grubbs catalyst (benzylidene dichloro(tricyclohexylphosphine)ruthenium) with 1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene. This method shows higher reaction activity, better stability, and improved functional group tolerance compared to the previous generation catalyst.

IV. Safety Information

GHS Classification: Flammable solid (Category 2), Signal word: “Warning”

Hazard Statement: H228 (Flammable solid)

Precautionary Statements:

UN Number: UN 1325

Hazard Class: 4.1 (Flammable solid)

Packing Group: PG II

WGK Germany: 3 (Hazardous to water)

Incompatible Materials: Acids, acid chlorides, acid anhydrides, oxidizing agents

Personal Protection: Wear safety goggles, protective gloves, and protective clothing; use N95 or P1 type respirator when necessary

Storage: Store in a cool, dry, well-ventilated warehouse, away from sources of ignition, protected by inert atmosphere (nitrogen or argon), and protected from light.