Supporting Information

Unprecedent Formation of Methylsilylcarbonates from Ir-

Catalyzed Reduction of CO2 with Hydrosilanes

Jefferson Guzmán, Pilar García-Orduña, Fernando J. Lahoz and Francisco J. Fernández-Alvarez*

Departamento de Química Inorgánica – Instituto de Síntesis Química y Catálisis Homogénea (ISQCH).

Universidad de Zaragoza. Facultad de Ciencias 50009, Zaragoza – Spain.

e-mail: paco@unizar.es.

Table of Contents

1. General information and experimental details .......................................................................2

2. NMR Characterization of complex 3 .....................................................................................3

3. NMR characterization of the methyl-silyl-carbonates species...............................................6

4. Control Experiment ..............................................................................................................14

5. Crystal Structure Determination of Complex 3 ....................................................................15

Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2020

1. General information and experimental details

All manipulations were carried out under an argon atmosphere by Schlenk-type techniques or in a Glovebox MBraun Unilab. Organic solvents were dried by standard procedures and distilled under argon prior to use or obtained oxygen- and water-free from a solvent purification system (Innovative Technologies). 1H, 13C, 29Si and 19F NMR spectra were obtained on a Bruker AV-300, AV-400 or AV-500 spectrometer. Chemical shifts (δ), reported in ppm, are referenced to the residual solvent peaks and coupling constants (J) are reported in Hz.

Synthesis of [Ir(NSiMe)2(CF3SO3)]2 (3). Toluene (10 mL) was added to a light-protected Schlenk containing [Ir(NSiMe)2(Cl)]2 (300 mg, 0.268 mmol) and silver triflate (151 mg, 0.590 mmol). The mixture was stirred at room temperature for 5 hours and then filtered through Celite. Solvent was removed under reduced pressure and the solid was washed with pentane (3 x 8 mL) to afford a white solid. Yield: 320 mg (89%). 1H NMR (300 MHz, C6D6, 298K): δ 8.73 (d, JH-H = 6.2 Hz, 2H, py), 6.32 (s, 2H, py), 6.02 (d, J H-H = 6.3 Hz, 2H, py), 1.51 (s, 6H, Me-py), 0.72 (s, 6H, Si-Me), 0.41 (s, 6H, Si-Me). 13C NMR (75 MHz, C6D6, 298K): δ 168.7 (s, py), 152.6 (s, py), 148.7(s, py), 118.4 (s, py), 111.9 (s, py), 20.6 (s, CH3-py), 3.8 (s, CH3-Si), 2.4 (s, CH3-Si). 29Si{1H} NMR plus 1H–29Si HMBC (60 MHz, C6D6, 298 K): δ 38.2 (Si-Ir). 19F NMR (282 MHz, C6D6, 298K): δ -76.97 (CF3SO3). High resolution mass spectrometry (ESI+): calc. m/z = 525.1006; found m/z = 525.1004 (M+-CF3SO3).

Catalytic Reactions with 1 mol% of 3. A Young cap NMR tube was charged with 1 mol% of 3 (2.83 mg, 0.0042 mmol), 0.42 mmol of the corresponding silane (114 µL, HSiMe(OSiMe3)2; 64.4 µL, HSiMe2Ph; 83.7 µL, HSiMePh2) and 0.5 mL of C6D6. Argon gas was evacuated by three freeze-pump-thaw cycles. Then the tube was pressurized with CO2 (3 bar) or 13CO2 (2.7 bar) and heated at 323 K.

Selected data for 13CH3O13CO2SiMe(OSiMe3)2. 1H NMR plus HSQC 1H–13C (300 MHz, C6D6, 298 K): δ 3.33 (dd, JH-C = 146.9, 4.1 Hz, 3H, CH3OCO2). 13C{1H} plus HSQC and HMBC 1H–13C (75 MHz, C6D6, 298 K): δ 153.0 (d, 2JC-C = 1.7 Hz, CO3), 54.1 (d, 2JC-C = 1.7 Hz, CH3O). 29Si{1H} DEPT-45 NMR plus 1H–29Si HMBC (60 MHz, C6D6, 298 K): −55.8 (br, CH3OCO2SiMe(OSiMe3)2).

Selected data for 13CH3O13CO2SiMe2Ph. 1H NMR plus HSQC 1H–13C (300 MHz, C6D6, 298 K): δ 3.30 (dd, 1JH-C = 147.1 Hz, 3JH-C = 4.1 Hz, 3H, CH3OCO2). 13C{1H} plus HSQC and HMBC 1H–13C (75 MHz, C6D6, 298 K): δ 154.1 (d, 2JC-C = 1.7 Hz, CO3), 54.2 (d, 2JC-C = 1.7 Hz, CH3O). 29Si{1H} DEPT-45 NMR plus 1H–29Si HMBC (60 MHz, C6D6, 298 K): 14.3 (d, 2JSi-C = 0.9 Hz, CH3OCO2SiMe2Ph).Selected data for 13CH3O13CO2SiMePh2. 1H NMR plus HSQC 1H–13C (300 MHz, C6D6, 298 K): δ 3.23 (dd, 1JH-C = 147.1 Hz, 3JH-C = 4.1 Hz, 3H, CH3OCO2). 13C{1H} plus HSQC and HMBC 1H–13C (75 MHz, C6D6, 298 K): δ 153.9 (d, 2JC-C = 1.7 Hz, CO3), 54.3 (d, 2JC-C = 1.7 Hz, CH3O). 29Si{1H} DEPT-45 NMR plus 1H–29Si HMBC (60 MHz, C6D6, 298 K): 2.07 (d, 2JSi-C = 1.1 Hz, CH3OCO2SiMePh2).

2. NMR Characterization of complex 3

-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5ppm

5.85

5.87

6.00

2.02

1.80

2.00

0.41

0.72

1.51

6.03

6.04

6.05

6.06

6.32

8.73

8.75

Figure S1. 1H-NMR spectrum of complex 3

-100102030405060708090100110120130140150160170180190ppm

2.4

3.8

20.6

111.

9

118.

4

148.

715

2.6

168.

7

Figure S2. 13C APT NMR spectrum of complex 3

-4-3-2-101234567891011121314ppm

-20

0

20

40

60

80

100

120

140

160

180

200

ppm

Figure S3. 1H–13C HSQC spectrum of complex 3

-1.5-0.50.51.52.53.54.55.56.57.58.59.5ppm

-10

0

10

20

30

40

50

60

70

80

90

100

ppm

Figure S4. 1H–29Si HMBC spectrum of complex 3

-140-135-130-125-120-115-110-105-100-95-90-85-80-75-70-65-60-55-50-45-40-35-30-25-20ppm

-76.

97

Figure S5. 19F NMR spectrum of complex 3

Figure S6. HR-MS spectrum of complex 3

3. NMR characterization of the methyl-silyl-carbonates species

-4.0-3.0-2.0-1.00.01.02.03.04.05.06.07.08.09.010.011.0ppm

A (d)3.40

B (dd)3.33

C (d)7.68

1.84

91.

000

2.09

1

3.08

3.10

3.16

3.57

3.59

3.64

7.31

8.06

Figure S7. 1H NMR from the 3-catalyzed reaction of 13CO2 with HMTS after 12 hours

2.752.802.852.902.953.003.053.103.153.203.253.303.353.403.453.503.553.603.653.703.753.803.853.90ppm

A (d)3.40

B (dd)3.33

1.84

9

1.00

0

3.08

3.10

3.16

3.57

3.59

3.64

Figure S8. 1H NMR detail showing the 13CH3O- products. [A = 13CH3OSiMe(OSiMe3)2; B = 13CH3O13CO2SiMe(OSiMe3)2]

-20-100102030405060708090100110120130140150160170180190ppm

-2.7

-1.8

1.6

1.9

49.6

54.1

54.1

153.

015

3.1

159.

1

151.5152.0152.5153.0153.5154.0154.5ppm

153.

015

3.1

53.753.853.954.054.154.254.354.4ppm

54.1

54.1

Figure S9. 13C{1H} NMR from the 3-catalyzed reaction of 13CO2 with HMTS after 12 hours (with details showing the 13C-13C coupling in the 13CH3O13CO2SiMe(OSiMe3)2 compound)

0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.5ppm

-20

-10

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

ppm

Figure S10. 1H–13C HSQC spectrum from the 3-catalyzed reaction of 13CO2 with HMTS

-2-1012345678910ppm

-10

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

ppm

Figure S11. 1H–13C HMBC spectrum from the 3-catalyzed reaction of 13CO2 with HMTS

1.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.05.2ppm

100

110

120

130

140

150

160

170

180

190

200

ppm

Figure S12. Detail from 1H–13C HMBC spectrum showing multiple bond correlation of the CH3O protons with the carbonate

Figure S13. 29Si DEPT from the 3-catalyzed reaction of 13CO2 with HMTS

0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.0ppm

3.29

3.30

7.71

3.263.273.283.293.303.313.323.33ppm

3.29

3.30

Figure S14. 1H NMR from the 3-catalyzed reaction of 12CO2 with HSiMe2Ph

2.802.852.902.953.003.053.103.153.203.253.303.353.403.453.503.553.603.653.70ppm

A (d)3.27

B (dd)3.30

1.00

0

0.73

7

3.04

3.04

3.06

3.51

3.53

3.55

Figure S15. 1H NMR detail from the 3-catalyzed reaction of 13CO2 with HSiMe2Ph (A, 13CH3OSiMe2Ph; B, 13CH3O13CO2SiMe2Ph)

-100102030405060708090100110120130140150160170180190ppm

50.4

54.2

54.2

154.

115

4.1

160.

3

153.5153.7153.9154.1154.3154.5ppm

154.

115

4.1

53.653.854.054.254.454.6ppm

54.2

54.2

Figure S16. 13C{1H} NMR from the 3-catalyzed reaction of 13CO2 with HSiMe2Ph (with details showing the 13C-13C coupling in the 13CH3O13CO2SiMe2Ph compound)

-1.0-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5ppm

-10

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

ppm

Figure S17. 1H–13C HMBC spectrum from the 3-catalyzed reaction of 13CO2 with HSiMe2Ph

Figure S18. 29Si DEPT from the 3-catalyzed reaction of 13CO2 with HSiMe2Ph

-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.0ppm

3.24

3.35

7.72

Figure S19. 1H NMR from the 3-catalyzed reaction of 12CO2 with HSiMePh2

2.22.32.42.52.62.72.82.93.03.13.23.33.43.53.63.73.83.94.04.14.24.3ppm

A (dd)3.23

B (d)3.35

1.05

3

0.40

2

2.98

2.99

3.11

3.47

3.48

3.59

Figure S20. 1H NMR detail from the 3-catalyzed reaction of 13CO2 with HSiMePh2 (A, 13CH3O13CO2SiMePh2; B, 13CH3OSiMePh2)

-100102030405060708090100110120130140150160170180ppm

51.0

54.3

54.3

153.

915

3.9

160.

1

153.70153.80153.90154.00154.10ppm

153.

915

3.9

53.954.154.354.554.7ppm

54.3

54.3

Figure S21. 13C{1H} NMR from the 3-catalyzed reaction of 13CO2 with HSiMePh2 (with details showing the 13C-13C coupling in the 13CH3O13CO2SiMePh2 compound)

1.81.92.02.12.22.32.42.52.62.72.82.93.03.13.23.33.43.53.63.73.83.94.04.14.24.34.44.54.6ppm

135

140

145

150

155

160

165

170

175

ppm

Figure S22. 1H–13C HMBC spectrum from the 3-catalyzed reaction of 13CO2 with HSiMePh2

Figure S23. 29Si DEPT from the 3-catalyzed reaction of 13CO2 with HSiMePh2

4. Control Experiment

-1.0-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.0ppm

Figure S24. 1H NMR from the mixture of CO2 and HSiMe(OSiMe3)2 in absence of 3 in C6D6

after 24h at 323K

5. Crystal Structure Determination of Complex 3

Single crystal X-ray diffraction data were collected at 100(2) K with graphite-monochromated Mo Kα radiation (λ=0.71072 Å) using narrow frame rotation (Δω=0.3°) on a Bruker Smart APEX diffractometer. Measured intensities were integrated and corrected for absorption effects with SAINT+S1 and SABABSS2 programs, included in APEX2 package. The structure was solved with direct methods with SHELXS-2013S3 and refined by full-matrix least-squares refinement on F2 with SHELXL-2018S4 program, included in WingX package.S5 The disordered solvent region has been analyzed with SQUEEZE program.S6

CCDC 1972218 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures.

Crystal data compound 3. C34H48F6Ir2N4O10S2Si4·0.5(H2O); M = 1364.65; colourless prism 0.140 x 0.240 x 0.330 mm3; triclinic , a = 9.0468(5), b = 12.0453(6), c = 12.0619(7) Å, 𝑃1̅

α=66.4720(10), β=88.5460(10), γ = 88.7690(10)°, V = 1204.65(11) Å3; Z = 1; Dc = 1.881 g/cm3; μ = 5.783 mm-1; Tmin/Tmax: 0.1676/0.5996; 23425/5849 reflections measured/unique (Rint = 0.0179), number of data/restraint /parameters 5849/0/286, R1(F2) = 0.0131 (5771 reflections, I> 2σ(I)) and wR(F2) = 0.0324 (all data), final GoF = 1.034, largest difference peak: 0.988 e.Å-3.

Crystallographic references

S1 SAINT+, version 6.01: Area-Detector Integration Software, Bruker AXS, Madison 2001.

S2 SADABS 2016/02. L. Krause, R. Herbst-Irmer, G. M. Sheldrick, D. Stalke, J. Appl. Crystallogr. 2015, 48, 3-10.

S2 (a) G. M. Sheldrick, Acta Crystallogr. A 1990, 46, 467-473; (b) G. M. Sheldrick, Acta Crystallogr. A 2008, 64, 112-122.

S3 G. M. Sheldrick, Acta Crystallogr. C 2015, 71, 3-8.

S4 L. J. Farrugia, J. Appl. Crystallogr. 2012, 45, 849-854.

S5 P. van der Sluis, A. L. Spek, Acta Crystalogr. 1990, A46, 194−201.

.