Dichloro[1,3-bis(2,4,6-trimethylphenyl-2H-imidazol-2-ylidene](tricyclohexylphosphine) (phenylalkylidene)ruthenium

Abstract

[223415-64-3] C46H64Cl2N2PRu (MW 847.96) InChI = 1S/C21H25N2.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;;;/h7-13H,1-6H3;16-18H,1-15H2;1-6H;2*1H;/q;;;;;+2/p-2 InChIKey = HOZCKNNRTFBZSB-UHFFFAOYSA-L (catalyst for olefin metathesis) Alternate Name: second generation Grubbs' catalyst; Nolan's ruthenium catalyst. Physical Data: soluble in tetrahydrofuran, acetone, dichloromethane, diethyl ether, and hydrocarbon solvents. Analysis of Reagent Purity: NMR spectroscopy: 1H NMR (500 MHz, C6D6): δ 19.91 (s, 1H, RuCH), 7.14 (m, 2H, o-H of C6H5), 6.97 (br m, 1H, p-H of C6H5), 6.89 (s, 4H, m-H of mesityl), 6.19 (s, 2H, NCHCHN), 6.15 (m, 2H, m-H of C6H5), 2.17 (s, 12H, o-CH3 of mesityl), 1.81 (s, 6H, p-CH3 of mesityl), 2.63, 2.51–2.48, 1.65, 1.53, 1.12 (all m, 33H, PCy3). 31P NMR (202.4 MHz, C6D6): δ 34.89 (s); elemental microanalysis. Preparative Methods: synthesis of RuCl2(CHPh)(IMes)(PCy3).2 Under inert atmosphere,3 using dry solvents, a 200 mL Schlenk flask is charged with RuCl2(CHPh)(PCy3)2, Grubbs' catalyst4 (5.0 g, 6.05 mmol), IMes·HCl5 (commercially available from Strem and Aldrich) (3.1 g, 9.1 mmol), KOtBu (1.55 g, 13.65 mmol), and dry hexanes (50 mL). The reaction mixture is then heated to 50 °C for 5 h and then allowed to cool to room temperature. The suspension is collected on a frit, washed with dry hexanes, and dried in vacuo to yield 78% (4.0 g) of 1 (pink-brown powdery solid). Another improved synthetic procedure is as follows:6 In a glove box a 200 mL Schlenk flask was charged with IMes·HCl5 (3.1 g, 9.10 mmol), potassium tert-amylate (1.26 g, 10.0 mmol), and dry hexanes (40 mL). The slightly turbid yellow reaction mixture was stirred at room temperature for 1 h. RuCl2(= CHPh)(PCy3)24 (5.0 g, 6.1 mmol) was added to the reaction mixture as a solid over 30 min to give a purple reaction mixture. The flask was removed from the glove box and stirred under 1 atm argon3 for 12 h. During the course of the reaction, the color of the mixture changed to pinkish-brown (the color of the precipitating product). The product was collected on a Schlenk frit and washed with hexanes (3 × 10 mL) then methanol (3 × 10 mL) and dried in vacuo to afford 4.8 g (92%) of 1. Purification: extract into benzene; remove solvent in vacuo. Handling, Storage, and Precautions: air stable complex, water tolerant. Glove box stable for 5 + months. Bench stable for up to 6 + weeks. Stable in toluene solution for > 21 d at 60 °C under inert conditions. Incompatible with acids Disposal: metal waste.