C-H Activation Reactions of Ruthenium N-Heterocyclic Carbene. Complexes: Application in a Catalytic Tandem Reaction Involving C-C

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1 SUPPORTING INFORMATION C-H Activation Reactions of Ruthenium N-Heterocyclic Carbene Complexes: Application in a Catalytic Tandem Reaction Involving C-C Bond Formation from Alcohols Suzanne Burling, Belinda M. Paine, Devendrababu Nama, Victoria S. Brown, Mary F. Mahon, Timothy J. Prior, Paul S. Pregosin, Michael K. Whittlesey and Jonathan M. J. Williams Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK, Down, Bath BA2 7AY, UK Laboratory of Inorganic Chemistry, ETHZ, Honggerberg, CH-8093 Zurich, Switzerland Station 16.2 SMX, CLRC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD, UK I. Molecular structures of complexes 4, 5, 6 and 7 S-2 II. Selected Bond Lengths (Å) and Angles (deg) for complexes 4-7 S-4 III. Crystal data and structure refinement for 6, 7, 9 and 11 S-5 IV. Tables of catalytic performance S-6 V. NMR Studies of 1 S-10 VI. Synthesis and characterisation of organic precursors S-13 S-1

2 I. Molecular structures of complexes 4, 5, 6 and 7. Molecular structure of compound 4. Thermal ellipsoids are represented at 30% probability. Carbon bound hydrogens have been omitted for clarity. Molecular structure of compound 5. Thermal ellipsoids are represented at 30% probability. Carbon bound hydrogens have been omitted for clarity. S-2

3 Molecular structure of compound 6. Thermal ellipsoids are represented at 30% probability. Carbon bound hydrogens have been omitted for clarity. Molecular structure of compound 7. Thermal ellipsoids are represented at 30% probability. Carbon bound hydrogens have been omitted for clarity. S-3

4 II. Table S-1. Selected Bond Lengths (Å) and Angles (deg) for complexes Ru-C NHC 2.171(3) 2.140(4) (19) 2.142(6) Ru-C CO 1.880(4) 1.883(6) 1.900(2) 1.864(3) Ru-P (13) (14) (5) (10) Ru-P (13) (14) (5) (10) C NHC -Ru-C CO 99.7(2) 100.8(2) (8) 99.1(2) P-Ru-P (4) (6) (19) (3) S-4

5 III. Table S-2. Crystal data and structure refinement for 6, 7, 9 and 11. Compound no Empirical formula C46 H48 N2 O P2 Ru C 46 H46 N2 O P2 Ru C 48 H50 N2 O P2 Ru C 46 H46 N2 O P2 Ru Formula weight Temperature 150(2) K 100(2) 150(2) 150(2) Crystal system Monoclinic Monoclinic Monoclinic Monoclinic Space group P21/n Cc P21/n P21/c a / Å (1) (3) (2) (17) b / Å (3) (1) (2) (3) c / Å (1) (3) (2) (5) α / o β / o (1) (1) (1) (3) γ / o U / Å (6) (9) (9) (12) Z Dc / g cm µ /mm F(000) Crystal size / mm 0.20 x 0.08 x x 0.30 x x 0.10 x x 0.03 x 0.03 Theta min./max. for data 3.70, , , , collection / o Index ranges -12<=h<=12; -43<=k<=43; -17<=l<=17-31<=h<=31; -11<=k<=11; -25<=l<=25-21<=h<=21; -23<=k<=23; -23<=l<=23-10<=h<=10; -17<=k<=16; -26<=l<=21 Reflections collected Independent reflections, R(int) 8809, , , , Reflections observed (>2σ) Max. and min. transmission 0.95 and , and , Data / restraints / parameters 8809 / 2 / / 5 / / 3 / / 18 / 506 Goodness-of-fit on F Final R indices [I>2σ(I)] , , , , R indices (all data) , , , , Largest diff. peak and hole / 0.411, , , , eå 3 S-5

6 IV. Tables of catalytic performance Entry Catalyst Alcohol Oxidation * (% Conversion into Ketone) Alkene Reduction * (% Conversion into Alkane) 1 h 12 h 6 h 12 h 1 Ru(PPh 3 ) 3 (CO)H Ru(ICy) 2 (PPh 3 )(CO)H * Reaction conditions: ([Ru] 2 mol%, C 6 D 6, 50 ºC). Table S-3. Catalytic data for (a) the oxidation of 4-fluoro-α-methylbenzylalcohol with acetone and (b) the reduction of trimethylvinylsilane with i PrOH. Conversions (%) are based on integration of 1 H NMR signals. S-6

7 Entry Catalyst Total Conversion (%) Alkene (%) Alkane (%) 1 Ru(PPh 3 ) 3 (CO)H Ru(ICy) 2 (PPh 3 )(CO)H Table S-4. Activity of various ruthenium complexes for the indirect Wittig reaction of benzyl alcohol and Ph 3 P=CHCN over 24 h at 80 ºC (1 ml toluene, 5 mol% Ru catalyst). S-7

8 Entry Catalyst Total Conversion (%) Alkene (%) Alkane (%) 1 Ru(PPh 3 ) 3 (CO)H Ru(ICy) 2 (PPh 3 )(CO)H Table S-5. Catalytic activity of ruthenium NHC complexes for reaction of benzyl alcohol and Ph 3 P=CHCN over 3 h at 70 ºC (1 ml toluene, 5 mol% Ru catalyst). S-8

9 Entry Catalyst Precursor Additive Alkene (%) Alkane (%) Total Conversion (%) 1 Ru(PPh 3 ) 3 (CO)H 2 None Ru(PPh 3 ) 3 (CO)H 2 IMes 1: Ru(PPh 3 ) 3 (CO)H 2 IMes 3: Ru(PPh 3 ) 3 (CO)H 2 IEt 2 Me 2 1: Ru(PPh 3 ) 3 (CO)H 2 IEt 2 Me 2 3: Ru(PPh 3 ) 3 (CO)H 2 I i Pr 2 Me 2 1: Ru(PPh 3 ) 3 (CO)H 2 I i Pr 2 Me 2 3: Table S-6. Activity for in situ catalysts in the indirect Wittig reaction of benzyl alcohol and Ph 3 P=CHCN (5 mol% Ru(PPh 3 ) 3 (CO)H 2, toluene, 70 ºC, 20 h). 100 Alkane Alkene 80 Conversion (%) None IMes 1:1 IMes 3:1 I i Pr 2 Me 2 1:1 I i Pr 2 Me 2 3:1 NHC equivalents to Ru(PPh 3 ) 3 (CO)H 2 Activity for in situ catalysts in the indirect Wittig reaction of benzyl alcohol and Ph 3 P=CHCN data from table S-6 S-9

10 V. NMR Studies of 1 The ambient temperature 1 H spectrum for 1 shows only two poorly resolved methyl signals (Fig. S-1). A series of variable temperature spectra eventually afford a 1 H spectrum at 233K that contains six non-equivalent methyl resonances. This result is consistent with restricted rotation around both the Ru-C IMes and N-C mesityl bonds. One of the two p-mesityl methyl groups is found at relatively low frequency, ca 1.2 ppm, which is assigned to a methyl group which is close to one or more of the phenyl groups of a PPh 3 ligand. A line shape analysis using the data from Figure S-xxx gave the following kinetic data: H =52.3 kj/mol, S =-3.6 J/K mol and G = 51.2 kj/mol. The rate constants derived from the variable temperature data are extracted by fitting the calculated line shape to the experiment. This was done by manual iteration and visual comparison. The iterative program MEXICO (version 3) was used. Line shape analysis over the temperature range 298 K to 223 K gave a set of rate constants, and the resulting plot of ln (k/t) Vs 1/T afforded the activation parameter E A from the Arrhenius equation Fig. S-2). Between 240 K and 255 K, the CH 3 signals at ca 2.5 ppm, ca 1.8 ppm and ca 1.2 ppm all appear to broaden at the same rate, even though these represent rather different methyl signals. Consequently, it is proposed that there is a single mechanism contributing to these exchange processes, perahps loss of phosphine, e.g., trans to the hydride ligand, followed by rapid rotation around both of the Ru-C IMes and N-C mesityl. The ambient temperature 1 H NOESY for 1 in the hydride region indicates exchange between the hydride ligands (see Fig. S-3). S-10

11 Fig. S-1. 1 H NMR spectra (methyl region) of complex 1 at different temperatures (pmesityl methyl groups are indicated by *). S-11

12 T(K) k(s -1 ) ln(k/t) y = x /T K-1 Fig. S-2. Rate constants for the internal exchange of the p-mesityl methyl of IMes ligand in 1 as a function of temperature and graph showing ln(k/t) vs 1/T for the same. Fig. S-3. Hydride region of 1 H- 1 H NOESY of 1 showing exchange between the two hydride resonances. S-12

13 VI. Synthesis and characterisation of organic precursors 1,3-Diisopropylimidazolium chloride Paraformaldehyde (3.0 g, 0.1 mol) was added under intense stirring to a toluene solution (100 ml) of isopropylamine (8.5 ml, 0.1 mol). After 30 min at room temperature, the mixture was cooled to 0 C and another equivalent of isopropylamine (8.5 ml, 0.1 mol) was added. The solution was stirred at 0 C for a further 10 min followed by dropwise addition of 4 M HCl in dioxane (25 ml, 0.1 mol) After warming to room temperature, 40 % aqueous glyoxal (14.5 ml, 0.1 mol) was added and the resulting cloudy mixture stirred at 37 C for 48 h. After cooling to room temperature, Et 2 O (100 ml) and a saturated Na 2 CO 3 solution (50 ml) were added, and the layers separated. The phase between the organic and aqueous layers was kept with the organic phase and the aqueous layer washed with Et 2 O (3 x 100 ml). The volatiles were removed in vacuo from the combined organic portions, and the residue extracted with dry CH 2 Cl 2 (50 ml), dried over MgSO 4 and filtered. After removal of the solvents, the solid residue was broken down to a pale brown hygroscopic powder by treatment with Et 2 O (50 ml). Yield: 10.1 g (54%). 1 H NMR (CDCl 3, 400 MHz): δ (br s, 1H, im-ch), 7.55 (s, 1H, HC=CH), 7.54 (s, 1H, HC=CH), 4.83 (sept, J HH = 6.7 Hz, 2H, CH(CH 3 ) 2 ), 1.50 (d, J HH = 6.7 Hz, 12H, CH(CH 3 ) 2 ). 13 C{ 1 H} NMR: δ (s, im- CH), (s, CH), 52.8 (s, CH(CH 3 ) 2 ), 22.8 (s, CH(CH 3 ) 2 ). 1,3-Bis(n-propyl)imidazolium chloride. The same procedure outlined above for the imidazolium salt was used, but n-propylamine was employed. The product was isolated as a pale yellow hygroscopic solid. Yield: 10.9 g (58%). 1 H NMR (CD 2 Cl 2, 400 MHz): δ (s, 1H, NCHN), 7.42 (s, 2H, im-ch), 4.29 (t, 4H, J HH = 7.3 Hz, N-CH 2 ), S-13

14 1.93 (m, 4H, CH 3 -CH 2 ), 0.97 (t, 6H, J HH = 7.3 Hz, CH 3 ). 13 C{ 1 H} NMR: δ (s, NCHN), (s, im-ch), 52.1 (s, N-CH 2 ), 24.4 (s, CH 3 -CH 2 ), 11.2 (s, CH 3 ). 1,3-Diisopropylimidazol-2-ylidene (I i Pr 2 ) A THF solution (15 ml) of 1,3- diisopropylimidazolium chloride (1.0 g, 5.3 mmol) and KO t Bu (0.7 g, 6.8 mmol) was stirred at -78 C for 1 h. The mixture was allowed to warm to room temperature before removing the volatiles in vacuo. The resulting oily residue was re-dissolved in toluene (15 ml), filtered through celite under argon and the volatiles removed. Hexane (20 ml) was added, the mixture filtered and the solvent removed in vacuo producing I i Pr 2 as a yellow oil. Yield: 0.66 g (81%). 1 H NMR (C 6 D 6, 400 MHz): δ 6.57 (s, 2H, HC=CH), 4.40 (sept, J HH = 6.7 Hz, 2H, CH(CH 3 ) 2 ), 1.26 (d, J HH = 6.7 Hz, CH(CH 3 ) 2 ). 13 C{ 1 H} NMR: δ (s, C:), (s, C=C), 52.8 (s, CH(CH 3 ) 2 ), 24.9 (s, CH(CH 3 ) 2 ). 1,3-Bis(n-propyl)imidazol-2-ylidene (I n Pr) A solution of 1,3-bis(npropyl)imidazolium chloride (1.0 g, 5.3 mmol) and KO t Bu (0.7 g, 6.8 mmol) in THF (15 ml) was stirred at -78 C for 30 min then allowed to warm to room temperature for 30 min. The solvent was removed in vacuo and the resulting oily residue redissolved in toluene (15 ml) and filtered through celite under argon. The solvent was removed in vacuo to give I n Pr as a yellow oil. Yield: 0.38 g (47%); 1 H NMR (C 6 D 6, 400 MHz): δ 6.45 (s, 2H, im-ch), 3.79 (t, 4H, J HH = 7.2 Hz, N-CH 2 ), 1.62 (m, 4H, CH 3 -CH 2 ), 0.73 (t, 6H, J HH = 7.2 Hz, CH 2 -CH 2 ). 13 C{ 1 H} NMR: δ (s, NCN), (s, im-ch), 53.3 (s, N-CH 2 ), 25.9 (s, CH 3 -CH 2 ), 11.9 (s, CH 3 ). (Cyanomethyl)triphenylphosphonium bromide To a solution of bromoacetonitrile (10.0 g, mmol) in toluene (150 ml) was added a solution of triphenylphosphine (21.9 g, mmol) in toluene (50 ml). The reaction flask was S-14

15 stoppered and set aside for 3 days at room temperature. The white precipitate obtained was collected via filtration and washed thoroughly with toluene (2 x 50 ml) and hexane (3 x 50 ml). Drying under vacuum afforded the title compound as a white powder. Yield: 29.6 g (93%). 1 H NMR (CDCl 3, 300 MHz): δ (m, 6H, CH), 7.80 (t, J HH = 7.1 Hz, 3H, CH), (m, 6H, CH), 6.42 (d, J PH = 15.4 Hz, 2H, CH 2 ). 31 P{ 1 H} NMR: δ 23.1 (s, PPh 3 ). (Triphenylphosphoranylidene)acetonitrile (Cyanomethyl)triphenylphosphonium bromide (5.0 g, 13.1 mmol) was dissolved in CH 2 Cl 2 (100 ml) and then extracted with KOH solution (2M, 2 x 50 ml). The collected aqueous extract was then extracted with further dichloromethane (25 ml). The combined organic fractions were then washed with brine (100 ml), dried (MgSO 4 ), filtered and concentrated in vacuo to afford the crude product as a cream solid. The title compound was obtained as colorless cubes following recrystallisation from the minimum volume of boiling benzene. Yield: 3.9 g (98%). 1 H NMR (CDCl 3, 300 MHz): δ (m, 9H, CH), (m, 7H, CH). 31 P{ 1 H} NMR: δ 24.2 (s, PPh 3 ). S-15