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Electronic Supplementary Information  

Aryl Appended Neutral and Cationic Half-sandwich Ruthenium(II)-NHC Complexes: Synthesis, Characterisation and Catalytic Applications

 

Mambattakkara Viji,a,b Nidhi Tyagi,a Neeraj Naithanic and Danaboyina Ramaiah*d

aPhotosciences and Photonics, Chemical Sciences and Technology Division CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, 695 019, India

bAcademy of Scientific and Innovative Research (AcSIR), CSIR-NIIST Campus cAnalytical and Spectroscopy Division, Vikram Sarabhai Space Centre, Trivandrum 695 022, India

dCSIR-North East Institute of Science and Technology, Jorhat 785 006, Assam

E-mail: rama@neist.res.in or d.ramaiah@gmail.com

Si. No Contents Page

1

Figures S1-S12 show 1H and 13C NMR spectra of the complexes 1-6

S2-S13

2 Figure S13 shows the electrochemical properties of the complexes 1-6 S14

3 Figure S14 shows the thermograms of the complexes 1, 2, 4 and 5 S15

4 Figure S15 shows the GC traces of the transfer hydrogenation products S16-S17

5 Figures S16-S24 show the 1H NMR spectra of the products isolated S18-S26

6 Characterization of the transfer hydrogenation products S27-S29

7 Table S1 shows the crystallographic data and processing parameters for the complexes 1-4

S30

8 Table S2 shows the selected bond lengths and bond angles for the complexes 1-4

S31

9 Table S3 shows the comparative efficiency of transfer hydrogenation of acetophenone using various catalysts

S32

10 Table S4 shows the optimized energy levels of intermediates and molecules involved in the mechanism.

S32

11 Scheme S1 shows the possible mechanism for TH reactions S33

Electronic Supplementary Material (ESI) for New Journal of Chemistry.This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2017

S2

 

 

Figure S1. 1H NMR spectrum of the complex 1 in CDCl3.

S3

 

Figure S2. 13C NMR spectrum of the complex 1 in DMSO.

S4

 

  

Figure S3. 1H NMR spectrum of the complex 2 in CDCl3.

S5

 

 

 

Figure S4. 13C NMR spectrum of the complex 2 in DMSO.

S6

 

 

Figure S5. 1H NMR spectrum of the complex 3 in CD3CN.

S7

 

 

Figure S6. 13C NMR spectrum of the complex 3 in CD3CN. 

S8

 

Figure S7. 1H NMR spectrum of the complex 4 in CD3CN.

S9

 

Figure S8. 13C NMR spectrum of the complex 4 in CD3CN.

S10

 

Figure S9. 1H NMR spectrum of the complex 5 in CD3CN.

S11

 

Figure S10. 13C NMR spectrum of the complex 5 in CD3CN.

S12

 

Figure S11. 1H NMR spectrum of the complex 6 in CD3CN.

S13

 

Figure S12. 13C NMR spectrum of the complex 6 in CD3CN.

S14

 

1.6 1.2 0.8 0.4 0.0

‐8.0x10‐6

‐4.0x10‐6

0.0Current(A)

Potential(V)

A)

1.6 1.2 0.8 0.4 0.0

‐1.2x10‐5

‐8.0x10‐6

‐4.0x10‐6

0.0

Current(A)

Potential(V)

B)

1.6 1.2 0.8 0.4‐1.0x10‐5

0.0

1.0x10‐5

2.0x10‐5

Current(A)

Potential(V)

C)

1.6 1.2 0.8 0.4‐2.0x10‐5

0.0

2.0x10‐5

4.0x10‐5

6.0x10‐5

Current(A)

Potential(V)

D)

1.6 1.2 0.8 0.4

‐1.0x10‐5

0.0

1.0x10‐5

2.0x10‐5

Current(A)

Potential(V)

E)

1.6 1.2 0.8 0.4‐2.0x10‐5

0.0

2.0x10‐5

Current(A)

Potential(V)

F)

Figure S13. Square-wave voltammograms of the complexes (1 mM each), A) 1 and B) 2 in

dichloromethane and cyclic voltammograms of the complexes, C) 3, D) 4, E) 5 and F) 6 in

acetonitrile at a scan rate of 100 mV/s.

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0 200 400 600 8000

50

100

0 200 400 600 8000

50

100C) D)

Weight(%)

Temperature(oC)

Weight(%)

Temperature(oC)

 

0 200 400 600 8000

50

100

0 200 400 600 8000

50

100

Weight(%)

Temperature(oC)

A)

Weight(%)

Temperature(oC)

B)

Figure S14. Theromograms of the complexes, A) 1, B) 2, C) 4 and D) 5.

S16

 

A) 1-Phenylethanol

3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 5.75 6.00 6.25 6.50 6.75

0.5

1.0

1.5

(x10,000,000)TIC

40 50 60 70 80 90 100 110 1200

50

100

%

79107

7712243 51

10853 63 12391 10241 938768

B) 1-(4-Chlorophenyl)ethanol

5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5

1.0

2.0

(x10,000,000)TIC

50.0 75.0 100.0 125.0 150.0 175.0 200.00.0

25.0

50.0

%77 141

43113

15651 103 1217563 91 155127 219

C) 1-(4-Iodophenyl)ethanol

7.50 7.75 8.00 8.25 8.50 8.75 9.00 9.25 9.50 9.75 10.00 10.25

1.0

2.0

(x10,000,000)TIC

50.0 75.0 100.0 125.0 150.0 175.0 200.0 225.0 250.00

50

100

%

78

23343

24812151 103 205 23463 91 127 217152 176165

D) Diphenylmethanol

7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0

1.0

2.0

(x10,000,000)TIC

50.0 75.0 100.0 125.0 150.0 175.0 200.0 225.00

50

100

%

105

77 184

51 1651528263 115 1391289140 243

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E) (4-Bromophenyl)(phenyl)methanol

13.25 13.50 13.75 14.00 14.25 14.50 14.75 15.00 15.25 15.50 15.75 16.00 16.25 16.50

0.5

1.0

(x10,000,000)TIC

50.0 75.0 100.0 125.0 150.0 175.0 200.0 225.0 250.00.0

25.0

%10577

183

51 165 26215563 89 139115 247127 16840 233195

F) 1-(p-Tolyl)ethanol

4.75 5.00 5.25 5.50 5.75 6.00 6.25 6.50 6.75 7.00

0.5

1.0

1.5

2.0

(x10,000,000)TIC

50.0 75.0 100.0 125.0 150.0 175.0 200.00

50

100

%

12193

43 1367765 11551 10367 134 219

G) Di-p-tolylmethanol

10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5 16.0 16.5 17.0

0.5

1.0

1.5

(x10,000,000)TIC

50.0 75.0 100.0 125.0 150.0 175.0 200.0 225.0 250.0 275.0 300.0 325.0 350.0 375.0 400.00.0

25.0

50.0

%119

91

21219765 77

16515241 128 388

H) 1-(3,4-Dimethoxyphenyl)ethanol

8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5

0.5

1.0

1.5

(x10,000,000)TIC

40 50 60 70 80 90 100 110 120 130 140 150 160 170 1800

50

100

%

164

14991 13977103 18212143 6551 89 108 14041 75

 

Figure S15. GC traces A-H of the hydrogenation products.

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Figure S16. 1H NMR spectrum of 1-phenylethanol in CD3CN.

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Figure S17. 1H NMR spectrum of 1-(4-iodophenyl)ethanol in CD3CN.

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Figure S18. 1H NMR spectrum of diphenylmethanol in CD3CN.

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Figure S19. 1H NMR spectrum of (4-bromophenyl)(phenyl)methanol in CD3CN.

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Figure S20. 1H NMR spectrum of 1-(4-chlorophenyl)ethanol in CD3CN.

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Figure S21. 1H NMR spectrum of 1-(p-tolyl)ethanol in CD3CN.

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Figure S22. 1H NMR spectrum of 1-(4-methoxyphenyl)ethanol in CD3CN.

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Figure S23. 1H NMR spectrum of 1-(3,4,5-trimethoxyphenyl)ethanol in CD3CN.

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Figure S24. 1H NMR spectrum of di-p-tolylmethanol in CD3CN.

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Characterization data for isolated transfer hydrogenation products obtained in the presence of complex 1 as a representative example.

1-Phenylethanol[1]: Using the general procedure the transfer hydrogenation of 1-phenylethanone

was carried out in the presence of complex 1 at 80 oC for 2 h. Product obtained as colourless oily

liquid, Isolated yield (11 mg, 96%); 1H NMR (CD3CN, TMS, 500 MHz) δ (ppm) 1.36-1.38 (d,

3H), 3.24 (s, 1H), 4.76-4.81 (q, 1H), 7.21-7.22 (t, 1H), 7.30-7.36 (m, 4H); HRMS (ESI), m/z

Calcd for C8H10O 122.073; Found 123.081 (M +1).

1-(4-Chlorophenyl)ethanol[2]: Using the general procedure the transfer hydrogenation of 1-(4-

Chlorophenyl)ethanone was carried out in the presence of complex 1 at 80 oC for 2 h. Product

obtained as yellow oily liquid, Isolated yield (15.4 mg, 98%); 1H NMR (CD3CN, TMS, 500

MHz) δ (ppm) 1.35-1.36 (d, 3H), 3.28 (s, 1H), 4.76-4.81 (q, 1H), 7.33 (m, 4H); HRMS (ESI),

m/z Calcd for C8H9ClO 156.034; Found 156.015 (M+).

1-(4-Iodophenyl)ethanol[3]: Using the general procedure the transfer hydrogenation of 1-(4-

Iodophenyl)ethanone was carried out in the presence of complex 1 at 80 oC for 2 h. Product

obtained as off-white solid, Isolated yield (24 mg, 97%); 1H NMR (CD3CN, TMS, 500 MHz) δ

1.34-1.35 (d, 3H), 3.27 (s, 1H), 4.74-4.76 (q, 1H), 7.14-7.16 (d, 2H), 7.67-7.68 (d, 2H); HRMS

(ESI), m/z Calcd for C8H9IO 247.979; Found 248.061 (M+).

Diphenylmethanol[1]: Using the general procedure the transfer hydrogenation of benzophenone

was carried out in the presence of complex 1 at 80 oC for 2 h. Product obtained as white solid,

Isolated yield (17.3 mg, 94%); 1H NMR (CD3CN, TMS, 500 MHz) δ (ppm) 3.82 (s, 1H), 5.77 (d,

1H), 7.20-7.23 (t, 2H), 7.29-7.32 (t, 4H), 7.36-7.38 (d, 4H); HRMS (ESI), m/z Calcd for C13H12O

184.088; Found 184.943 (M+).

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(4-Bromophenyl)(phenyl)methanol[4]: Using the general procedure the transfer hydrogenation

of (4-Bromophenyl)(penyl)methanone was carried out in the presence of complex 1 at 80 oC for

2 h. Product obtained as off-white solid, Isolated yield (23.5 mg, 89%); 1H NMR (CD3CN, TMS,

500 MHz) δ 3.88 (s, 1H), 5.74 (d, 1H), 7.29-7.36 (m, 7H), 7.46-7.47 (d, 2H); HRMS (ESI), m/z

Calcd for C13H11BrO 261.999 and 263.997; Found 262.989 (M+1) and 263.992.

1-(p-Tolyl)ethanol[1]: Using the general procedure the transfer hydrogenation of 1-(p-

Tolyl)ethanone was carried out in the presence of complex 1 at 80 oC for 3 h. Product obtained as

light yellow oily liquid, Isolated yield (12.6 mg, 92%); 1H NMR (CD3CN, TMS, 500 MHz) δ

(ppm) 1.34-1.35 (d, 3H), 2.30 (s, 3H), 3.1 (s, 1H), 4.74-4.76 (q, 1H), 7.13-7.14 (d, 2H), 7.22-7.24

(d, 2H); HRMS (ESI), m/z Calcd for C9H12O 136.088; Found 136.064 (M+).

1-(4-Methoxyphenyl)ethanol[5]: Using the general procedure the transfer hydrogenation of 1-(4-

Methoxyphenyl)ethanone was carried out in the presence of complex 1 at 80 oC for 3 h. Product

obtained as light brown oil, Isolated yield (13.4 mg, 88%); 1H NMR (CD3CN, TMS, 500 MHz) δ

(ppm) 1.36-1.37 (d, 3H), 3.07-3.08 (d 1H), 3.76 (s, 3H), 4.71-4.76 (q, 1H), 6.86-6.88 (m, 2H),

7.26-7.27 (m, 2H); HRMS (ESI), m/z Calcd for C9H12O2 152.083; Found 152.076 (M+).

Di-p-tolylmethanol[6]: Using the general procedure the transfer hydrogenation of Di-p-

tolylmethanone was carried out in the presence of complex 1 at 80 oC for 3 h. Product obtained

as off-white solid, Isolated yield (19.5 mg, 91%); 1H NMR (CD3CN, TMS, 500 MHz) δ 2.28 (s,

6H), 3.66 (s, 1H), 5.67-5.68 (d, 1H), 7.10-7.12 (d, 4H), 7.21-7.23 (d, 4H); HRMS (ESI), m/z

Calcd for C15H16O 212.120; Found 212.113 (M+).

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Transfer hydrogenation of 1-(4-Chlorophenyl)ethanone in the presence of complex 1

 

A solution of complex 1(19.4 mg, 0.02 mmol, 2 mol%) in 20 mL of 2-propanol was

sonicated for 10-15 minutes. Then NaOH was (40 mg, 1 mmol) was added and preheated the

solution for 10 minutes. The substrate 1-(4-Chlorophenyl)ethanone (154 mg, 1 mmol) was then

added slowly and allowed the reaction mixture to reflux at 80 oC for 2 h. After completing the

reaction, the reaction mixture was passed through a small pad of silica and elute with hexane.

The solvent was evaporated to dryness to yield yellow oily liquid (142 mg, 91%), 1-(4-

Chlorophenyl)ethanol as the product. The product was characterized by spectral and analytical

techniques. 1H NMR (CD3CN, TMS, 500 MHz) δ (ppm) 1.35-1.36 (d, 3H), 3.28 (s, 1H), 4.76-

4.81 (q, 1H), 7.33 (m, 4H); 13C NMR (CD3CN, 125 MHz) δ (ppm) 24.5, 68.1, 126.7, 127.8,

131.5, 145.5.

REFERENCES

[1]. P. N. Liu, K. D. Ju and C. P. Lau, Adv. Synth. Catal., 2011, 353, 275.

[2]. Y. Xu, G. C. Clarkson, G. Docherty, C. L. North, G. Woodward and M. Wills,

J. Org. Chem., 2005, 70, 8079.

[3]. T. Saito, Y. Nishimoto, M. Yasuda and A. Baba, J. Org. Chem., 2006, 71, 8516.

[4]. F. Zhou and C.-J. Li, Nat. Commun., 2014, 5, 4254.

[5]. H. L. Ngo and W. Lin, J. Org. Chem., 2005, 70, 1177.

[6]. B. Denegri and O. Kronja, J. Org. Chem., 2007, 72, 8427.

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Table S1. X-ray crystal structure refinement data of the complexes 1-4.

Complex 1 Complex 2 Complex 3 Complex 4

Crystal system Triclinic Monoclinic Monoclinic Monoclinic

Space group P -1 P 21/c P 21/c C 2/c

a (Å) 8.201(6) 16.376(11) 13.3979(7) 29.1612(11)

b (Å) 9.946(7) 10.424(7) 10.3168(5) 12.5438(5)

c (Å) 21.325(15) 20.145(10) 19.7429(9) 16.5284(6)

(˚) 81.89(3) 90 90 90

γ (˚) 87.42(2) 90 90 90

β (˚) 84.71(2) 127.64(4) 101.468(2) 103.261(2)

V (Å3) 1714(2) 2723(3) 2674.45 5884.75

Z 1 2 4 8

Temperature /K 150(2) 150(2) 150(2) 296(2)

λ (Å) (Mo-Kα) 0.71073 0.71073 0.71073 0.71073

Crystal size (mm) 0.4x0.2x0.1 0.1x0.1x0.1 0.2x0.15x0.1 0.2x0.15x0.1

F(000) 846 1356 1312 2752

Theta range for data

collection

3.0-27.4 3.14-26.35 2.24-28.22 3.00-26.25

Data/restraints/parameters 7351/0/ 354 5531/0/281 13667/0/799 15656/0/ 1025

GOF on F2 1.210 1.226 1.050 0.999

R1 [I > 2σ(I)] 0.0785 0.1139 0.0352 0.0577

wR2 [I > 2σ(I)] 0.2043 0.2066 0.0876 0.1840

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Table S2. Selected bond lengths (Å) and angles (deg) of the complexes 1-4.

SI.No. Bond Lengths (Å) Bond Angles (deg)

Complex 1 C4-Ru1 2.074(7) C4-Ru-Cl3 89.0(2)

Cl2-Ru1 2.457(2) C4-Ru1-Cl2 89.44(19)

Cl3-Ru1 2.470(2) C4-Ru1-Cl3 89.0(2)

Ru1-CAr 1.719(2)

Complex 2 C1-Ru1 2.056(11) C1-Ru1-Cl1 90.0(3)

Cl1-Ru1 2.452(3) C1-Ru1-Cl2 89.70(3)

Cl2-Ru1 2.441(2) Cl2-Ru1-Cl1 83.49(9)

Ru1-CAr 1.693(2)

Complex 3 C1-Ru1 2.017(3) Cl1-Ru1-C1 84.11(7)

N3-Ru1 2.095(2) N3-Ru1-C1 76.65(11)

Cl1-Ru1 2.405(7) Cl1-Ru1-N3 84.14(7)

Ru1-CAr 1.714(3)

Complex 4 C12-Ru1 2.025(5) Cl1-Ru1-C12 84.84(14)

N4-Ru1 2.106(4) N4-Ru1-C12 76.04(18)

Cl1-Ru1 2.414(13) Cl1-Ru1-N4 88.76(12)

Ru1-CAr 1.740(2)

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Table S3. Comparative efficiency of transfer hydrogenation of acetophenone in the presence of various catalysts.a

Entry Substrate Catalyst Conversion (%)

1

Complexes 1-2 90-100

2 ” Complexes 3-6 100

3 ” Ligands L1-L5 No reaction

4 ” [Ru(p-Cymene)Cl2]2 ~47

5 ” Hoveyda-Grubbs’ 2nd ~60 a Reaction conditions: acetophenone (0.1 mmol), catalysts entries 1, 3, 4 and 5 (2 mol%), catalyst entry 2 (0.5 mol%), NaOH (0.1 mmol), 2-propanol (2 mL), temperature (80 ± 2 °C) and reaction time, 1-5 h.

Table S4. Optimized energy levels of intermediates and molecules involved in the mechanism. a

 

Intermediate/Molecules Energy (a.u.)

(A) -1420.66

(B) -1227.47

(D) -1612.37

Acetone -193.13

Isopropanol -194.33

Acetophenone -384.84

1-Phenylethanol -386.04

aAverage of three independent calculations.

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Scheme S1. Possible mechanism for transfer hydrogenation of acetophenone using complex 3 as

a representative example.