Highly Efficient and Selective Methanol Production from Paraformaldehyde and Water at Room Temperature

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1 Supporting Information Highly Efficient and Selective Methanol Production from Paraformaldehyde and Water at Room Temperature Lin Wang, Mehmed Z. Ertem*, Kazuhisa Murata, James T. Muckerman, Etsuko Fujita and Yuichiro Himeda* Research Institute of Energy Frontier, Department of Energy and Environment National Institute of Advanced Industrial Science and Technology Tsukuba Central 5, Higashi, Tsukuba, Ibaraki, , Japan Chemistry Division, Brookhaven National Laboratory, Upton, NY , USA General experimental information...s2 Figure S1. Two selected results via high-performance liquid chromatography (HPLC)...S4 Figure S2. In situ analysis of the ph change of the reaction process under optimal conditions using catalyst 7...S5 Figure S3. Time course of methanol yields for catalysts 5, 6, and 7..S5 Figure S4. 1 H NMR spectrum of hydride species [Ir H] generated by the reaction of [Ir H] with sodium formate...s6 Figure S5. 1 H NMR spectra of (HCHO) n in D2O (A) and (DCDO) n in H2O (B) using S7 Figure S6. Reaction rate profiles for methanol production in the presence of catalyst S8 Table S1. The effect of paraformaldehyde concentration for methanol production with catalyst effect of paraformaldehyde concentration for methanol production with catalyst 7 in water...s8 Table S2. The effect of temperature for methanol production with catalyst 7...S8 S1

2 Table S3. Kinetic isotope effect for methanol production catalyzed by catalyst 7....S9 Table S4. Computed kinetic isotope effects for methanol production catalyzed by catalyst 7 S9 Computational Methods......S9 Table S5. Computed relative free energies ( G) in units of kcal/mol and pkas for hydrogen bonded structures of H2C(OH)2 and H2C(OH)O with water molecules s10 Figure S7. Computed relative free energies ( G) in units of kcal/mol at ph 12 for selected reaction intermediates and protonation states of complex 6 in reference to most stable protonation state shown in bold....s11 Table S6. Computed relative free energies ( G) in units of kcal/mol and pkas for hydrogen bonded structures of H2C(OH)2 and H2C(OH)O with water molecules s11 Table S7. Computed relative free energies ( G) in units of kcal/mol at ph 12 for selected reaction intermediates and protonation states of complex 6 in reference to most stable protonation state shown in bold s12 Table S8. Computed relative free energies ( G) in units of kcal/mol at ph 12 for selected reaction intermediates and protonation states of complex 7 in reference to most stable protonation state shown in bold s12 Scheme S1. Proposed mechanism for methanol production from a paraformaldehyde-water solution s12 Table S9. Computed free-energy changes ( Gs) and activation free energies ( G s) at ph 12 for the chemical steps in the proposed mechanism for the methanol production in Scheme S1 for selected protonation states of complexes 7 S13 References S13 Cartesian Coordinates of Optimized Structures at M06 Level of Theory..S15 General Information All manipulations were carried out under an Ar or N2 atmosphere using standard Schlenk techniques, and all the materials were purchased from commercial suppliers and used without further purification. Paraformaldehyde (white powder, 94.0+% as HCHO) was purchased from Wako Pure Chemical Industries Ltd. All aqueous solutions were degassed prior to use. 1 H NMR spectra were recorded on Bruker Avance 400 and 500 spectrometers using tetramethylsilane or sodium 3-(trimethylsilyl)-1-propanesulfonate as an internal standard. Elemental analyses were performed by a CE Instrument EA1110 elemental analyzer. ESI-MS data were collected on a Shimadzu LCMS The ph values were measured with an Orion 3-Star ph meter with a glass electrode after calibration with standard buffer solutions. The content of the generated gas S2

3 was analyzed by a GL Science GC-390 gas chromatograph. H2 was detected by a thermal conductivity detector (TCD) using an activated 60/80 carbon column; CO2 and/or CO were detected by using a flame ionization detector (FID) equipped with a methanizer using a Porapak Q 80/100 column at 50 ºC. Formaldehyde, methanol, and formate concentrations were monitored by an HPLC on an anion-exclusion column (Tosoh TSK gel SCX(H + )) using an aqueous H3PO4 solution (20 mm) as an eluent and a refractive index detector (RID). Water used in the reactions was obtained from a Simplicity water purification system. The methanol selectivities (yields) are given as a percentage relative to the maximum two thirds conversion from paraformaldehyde (one third is CO2), which are the average of at least two runs unless otherwise mentioned. Complexes 1-9 were prepared according to our previously reported procedures. 1-3 General procedure for catalytic methanol production from paraformaldehyde and water: In a 10 ml flask, paraformaldehyde (3 mmol), K2CO3 (10 mol%), and complexes (2.5 mol) were added in 5 ml water (degassed by three cycles of freeze-pump-thaw), then the mixture was stirred at the desired temperature under argon atmosphere. The concentration changes of formaldehyde, methanol, and formate were determined by an HPLC with a RID detector (as described in the Method). The reactions were generally carried out more than twice; and the average values of the yield (TOF and TON) were presented. Their errors were less than 5% under the same conditions. General Procedure for the formation of Ir H species in the catalytic cycle B ( 1 H NMR study): First of all, according to the reported work, 4 the hydroxy complex of 6 (denoted here as 6 OH that corresponds Ir OH in scheme 2) was synthesized. To a mixture of 6 OH (4.6 mg, 8.0 mol) and sodium formate (2.8 mg, 40.0 mol) under Ar atmosphere, a deaerated D2O (0.5 ml) was added at room temperature. After stirring 20 min, the mixture was transferred into a NMR tube, and then measured by a 1 H NMR spectrum. Similarly, in the presence of the newly synthesized hydroxyl complex of 7, 7 OH, with sodium formate, the Ir H species in the catalytic cycle B of scheme 2 was formed at ppm. However, the detection of Ir H species in the catalytic cycle A was difficult because of the rapid formation of methanol when Ir H species met methanediol. S3

4 (a) reaction time = 2 h 1 HCHO HCOOH CH 3OH (min) peak retention time (min) Area Area % total (b) reaction time = 16 h 3 CH 3OH HCHO HCOOH (min) peak retention time (min) Area Area % total Figure S1. Two selected results via high-performance liquid chromatography (HPLC) at 2 h (a) and 16 h (b) during the reaction. Conditions: paraformaldehyde (3 mmol), catalyst 7 (2.5 mol), H2O (5 ml), K2CO3 (10 mol%), 30 C, all the reactions were carried out under Ar atmosphere. S4

5 Figure S2. In situ analysis of the ph change of the reaction process under optimal conditions using catalyst 7 at 30 C. Figure S3. Time course of methanol yields for catalysts 5, 6, and 7. Conditions: paraformaldehyde (3 mmol, 90 mg), catalyst (2.5 mol), H2O (5 ml), K2CO3 (10 mol%), 30 C, All the data were determined by HPLC. S5

6 (a) Catalyst 6 (b) 6 OH (c) 6 OH+SF Ir-H Figure S4. 1 H NMR spectrum of hydride species [Ir H] generated by the reaction of hydroxo complex [Ir H] with sodium formate (SF). (a) Catalyst 6 in D2O, (b) 6 OH in D2O, (c) 6 OH with 5 eq. SF in D2O. S6

7 (A) CH3OD (B) Only CD3OH No CH3OH peak Internal standard: CH3CN Figure S5. 1 H NMR spectra of (HCHO)n in D2O (A) and (DCDO)n in H2O (B). Conditions: paraformaldehyde (3 mmol, 90 mg), catalyst 7 (2.5 mol), H2O or D2O (5 ml), K2CO3 (10 mol%), 30 C, 8 h, CH3CN as the internal standard. S7

8 Figure S6. Reaction rate profiles for methanol production in the presence of catalyst 7. Conditions: paraformaldehyde (3 mmol), catalyst 7 (0.2 mol), H2O (5 ml), K2CO3 (10 mol%), 30 C. All the data were determined by HPLC. Table S1. The effect of paraformaldehyde concentration for methanol production with catalyst 7 in water a entry H2O /ml conc. of (HCHO)n/M yield b /% c c c a Reaction conditions: paraformaldehyde (3 mmol, 90 mg), catalyst 7 (2.5 mol), K 2CO 3 (10 mol%), 30 C, 16 h, all the reactions were carried out under Ar atmosphere. b HPLC yield. c Run for 22 h Table S2. The effect of temperature for methanol production with catalyst 7 a entry T/ C Yield b /% c c d a Reaction conditions: paraformaldehyde (3 mmol, 90 mg), catalyst 7 (2.5 mol), H 2O (5 ml), K 2CO 3 (10 mol%), 22 h, all the reactions were carried out under Ar atmosphere. b HPLC yield. c Run for 8 h. d Run for 27 h. S8

9 Table S3. Kinetic isotope effect for methanol production catalyzed by catalyst 7. [a] Entry Substrate Solvent KIE [b] 1 (HCHO)n H2O 2 (HCHO)n D2O (DCDO)n H2O (DCDO)n D2O 1.7 [a] Reaction conditions: substrate (3 mmol), H 2O (5 ml), catalyst 7 (0.2 mol), K 2CO 3 (10 mol%), 30 C. [b] KIE = reaction rate(entry 1)/ reaction rate (entry n), (n = 2, 3, and 4), the reaction rates based on the slopes in Figure S6. Table S4. Computed kinetic isotope effects for methanol production catalyzed by catalyst 7. Entry Substrate Solvent β-hydride [Ir-H] 3- reaction with elimination [Ir-HOCH2OH] 2- H2CO H2C(OH)2 H2C(OH)O 1 (HCHO)n H2O 2 (HCHO)n D2O (DCDO)n H2O (DCDO)n D2O Computational Methods All geometries were fully optimized at the M06 level of density functional theory 5 with the SMD aqueous continuum solvation model 6 using the Stuttgart [8s7p6d2f 6s5p3d2f] ECP60MWB contracted pseudopotential basis set 7 on Ir and the 6-31G(d,p) basis set 8 on all other atoms. Non-analytical integrals were evaluated using the integral=grid=ultrafine option as implemented in the Gaussian 09 software package. 9 The nature of all stationary points was verified by analytic computation of vibrational frequencies, which were also used for the computation of zero-point vibrational energies, molecular partition functions, and for determining the reactants and products associated with each transition-state structure (by following the normal modes associated with imaginary frequencies). 10 Partition functions were used in the computation of 298 K thermal contributions to the free energy employing the usual ideal-gas, rigid-rotator, harmonic oscillator approximation. 10 Free-energy contributions were added to single-point, SMD-solvated M06 electronic energies computed at the optimized geometries obtained with the initial basis with the SDD basis set on Ir and the larger G(2d,p) basis set 8 on all other atoms to arrive at final, composite free energies. As mentioned above, solvation effects associated with water as the solvent were accounted for using the SMD aqueous S9

10 continuum solvation model. 6 For all non-gas species, a 1 M standard state was used for all species in solution, thus, an adjustment for the 1 atm to 1 M standard-state concentration change of RT ln(24.5), (1.89 kcal/mol at 298 K) was added to the computed free energies. In the case of the water solvent, the 1 atm gas-phase free energy is adjusted by the sum of a 1 atm to 1 M standard-state concentration change (1.89 kcal/mol), the experimental 1 M to 1 M self-solvation free energy ( 6.32 kcal/mol) and a 55.4 M to 1 M standard-state concentration change (2.38 kcal/mol) yielding an overall correction of 2.05 kcal/mol to the gas-phase free energy. The 1 M to 1 M solvation free energy of the proton was taken from experiment as kcal/mol. 11 The computed relative free energies ( G) of hydrogen bonded structures of H2C(OH)2 and H2C(OH)O with water molecules were tracked via including explicit solvent (H2O) molecules in geometry optimizations, results of which are summarized in Table S5. The computed Gs indicate that the H2C(OH)O anion is significantly stabilized by hydrogen bonding with explicit H2O molecules whereas the effect is negligible for the neutral H2C(OH)2 molecule, which are in line with the expected performance of continuum solvation models with anionic and neutral molecules. The computed pka decreases with inclusion of explicit solvent (H2O) molecules and is closest to the experimental value (pka = 13.3) with three explicit H2O molecules (pka calc = 15.0). Therefore, for the computation of activation free energies ( G ) associated with the reactions of [Ir H] species with H2C(OH)2 and H2C(OH)O, which also involves three explicit water molecules, free energies of H2C(OH)2 and H2C(OH)O with three explicit water molecules are employed. Table S5. Computed relative free energies ( G) in units of kcal/mol and pkas for hydrogen bonded structures of H2C(OH)2 and H2C(OH)O with water molecules. Number of explicit H2O molecules H2C(OH) H2C(OH)O pka We also tested the effect of inclusion of explicit solvent (H2O) molecules on the structures of optimized TSs and G s associated with the reactions of [Ir H] species with H2C(OH)2 and H2C(OH)O for complex 6 (Figure S7 and Table S6). S10

11 (a) (b) (c) (d) (e) (f) Figure S7. Optimized transition state structures of complex 6 for [Ir H] reaction with (a) H2C(OH)2, (b) H2C(OH)2 + H2O, (c) H2C(OH)2 + 2 H2O, (d) H2C(OH)2 + 3 H2O, (e) H2C(OH)O + 2 H2O, (f) H2C(OH)O + 3 H2O. Table S6. Computed activation free energies ( G ) with respect to separated reactants in units of kcal/mol of complex 6 for [Ir H] reaction with H2C(OH)2 and H2C(OH)O in the presence of explicit water molecules (see Figure S7) Number of explicit H2O molecules H2C(OH) H2C(OH)O S11

12 Table S7. Computed relative free energies ( G) in units of kcal/mol at ph 12 for selected reaction intermediates and protonation states of complex 6 in reference to most stable protonation state shown in bold. [Ir] [Ir OH2] [Ir OH] [Ir HOCH2OH] [Ir OCH2OH] [Ir H] Table S8. Computed relative free energies ( G) in units of kcal/mol at ph 12 for selected reaction intermediates and protonation states of complex 7 in reference to most stable protonation state shown in bold. [Ir] [Ir OH2] [Ir OH] [Ir HOCH2OH] [Ir OCH2OH] [Ir H] Scheme S1. Proposed mechanism for methanol production from a paraformaldehyde-water solution. S12

13 Table S9. Computed free-energy changes ( Gs) and activation free energies ( G s) at ph 12 for the chemical steps in the proposed mechanism for the methanol production in Scheme S1 for selected protonation states of complexes 7. Complex 7 G G G G G a (22.3) b 45.5 a (21.3) b 45.2 a (21.3) b G G G G G G G a The computed activation free energies are with respect to [Ir H] and [H2C(OH)2 H2O)3] complexes as reactants b The computed activation free energies are with respect to [Ir H] and [(H2C(OH)O ) H2O)3] complexes as reactants References (1) Himeda, Y.; Onozawa-Komatsuzaki, N.; Miyazawa, S.; Sugihara, H.; Hirose, T.; Kasuga, K. ph-dependent Catalytic Activity and Chemoselectivity in Transfer Hydrogenation Catalyzed by Iridium Complex with 4,4 -Dihydroxy-2,2 -bipyridine. Chem.-Eur. J. 2008, 14, (2) Himeda, Y. Highly Efficient Hydrogen Evolution by Decomposition of Formic Acid Using an Iridium Catalyst with 4,4 -Dihydroxy-2,2 -bipyridine. Green Chem. 2009, 11, (3) Wang, W. -H.; Muckerman, J. T.; Fujita, E.; Himeda, Y. Mechanistic Insight through Factors Controlling Effective Hydrogenation of CO2 Catalyzed by Bioinspired Proton-Responsive Iridium(III) Complexes. ACS Catal. 2013, 3, (4) Fujita, K. -I.; Kawahara, R.; Aikawa, T.; Yamaguchi, R. Hydrogen Production from a Methanol Water Solution Catalyzed by an Anionic Iridium Complex Bearing a Functional Bipyridonate Ligand under Weakly Basic Conditions. Angew. Chem. Int. Ed. 2015, 54, (5) (a) Y. Zhao, D. G. Truhlar, Density Functionals with Broad Applicability in Chemistry. Acc. Chem. Res. S13

14 2008, 41, ; (b) Y. Zhao, D. G. Truhlar, The M06 Suite of Density Functionals for Main Group Thermochemistry, Thermochemical kinetics, Noncovalent Interactions, Excited States, and Transition Elements: Two New Functionals and Systematic Testing of Four M06-Class Functionals and 12 Other Functionals. Theor. Chem. Acta 2008, 120, ; (c) Y. Zhao, D. G. Truhlar, The Minnesota Density Functionals and their Applications to Problems in Mineralogy and Geochemistry. Rev. Mineral. & Geochem. 2010, 71, (6) A. V. Marenich, C. J. Cramer, D. G. Truhlar, Universal Solvation Model Based on Solute Electron Density and on a Continuum Model of the Solvent Defined by the Bulk Dielectric Constant and Atomic Surface Tensions. J. Phys. Chem. B 2009, 113, (7) D. Andrae, U. Haußermann, M. Dolg, H. Stoll, H. Preuß, Energy-Adjustedab initio Pseudopotentials for the Second and Third Row Transition Elements. Theor. Chem. Acta 1990, 77, (8) W. J. Hehre, L. Radom, P. V. R. Schleyer, J. A. Pople, Ab Initio Molecular Orbital Theory, Wiley: New York, (9) M. J. T. Frisch, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J., Revision A.02. ed., Gaussian, Inc.: Wallingford, CT, (10) C. J. Cramer, Essence of Coputational Chemistry: Theories and Models. 2nd ed., John Wiley & Sons: Chichester, (11) (a) M. D. Tissandier, K. A. Cowen, W. Y. Feng, E. Gundlach, M. H. Cohen, A. D. Earhart, J. V. Coe, J. Thomas R. Tuttle, The Proton's Absolute Aqueous Enthalpy and Gibbs Free Energy of Solvation from Cluster-Ion Solvation Data. J. Phys. Chem. A 1998, 102, ; (b) D. M. Camaioni, C. A. Schwerdtfeger, Comment on Accurate Experimental Values for the Free Energies of Hydration of H +, OH -, and H3O +. J. Phys. Chem. A 2005, 109, ; (c) C. P. Kelly, C. J. Cramer, D. G. Truhlar, Aqueous Solvation Free Energies of Ions and Ion Water Clusters Based on an Accurate Value for the Absolute Aqueous Solvation Free Energy of the Proton. J. Phys. Chem. B 2006, 110, ; (d) V. S. Bryantsev, M. S. Diallo, W. A. G. III, Calculation of Solvation Free Energies of Charged Solutes Using Mixed Cluster/Continuum Models. J. Phys. Chem. B 2008, 112, S14

15 Cartesian Coordinates of Optimized Structures at M06 Level of Theory Small Molecules H2O O H H CO2 C O O H3COH C H H O H H OCH2 C H H O HCOO C H O O H2C(OH)2 C H H O H O H H2C(OH)2 (H2O) C H H O H O H O H H H2C(OH)2 (H2O)2 C H H O H O H O H H O H H H2C(OH)2 (H2O)3 C H H O H O H O H H O H H O H H H2C(OH)(O ) C H H O H O H2C(OH)(O ) (H2O) C H H O O H O H H S15

16 H2C(OH)(O ) (H2O)2 C H H O O H O H H O H H H2C(OH)(O ) (H2O)3 C H H O O H O H H O H H O H H (Cp*Ir(Bpy)) [Ir] 2+ Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N H H [Ir OH2] 2+ Ir C C C C C C H H H C H H H C H H H C H H S16

17 H C H H H C C C C C C C C C C H H H H H H N N O H H H H [Ir OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O H H H [Ir HOCH2OH] 2+ Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C S17

18 C C C C C C C C H H H H H H N N O H H C H H O H H [Ir HOCH2OH] 2+ β-hydride elimination TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O C H H O H H H H [Ir OCH2OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H S18

19 C C C C C C C C C C H H H H H H N N O H H C H H O H [Ir OCHO] + β-hydride elimination TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O C O H H H [Ir H] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C S19

20 C C C C C C C C H H H H H H N N H H H [Ir H] + attack to H2C(OH)2 (H2O)3 TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N C H H H O H O H O H H O H H O H H H H [Ir OCH3] + Ir C C C C C C H H H C H H H C H H H C H H H S20

21 C H H H C C C C C C C C C C H H H H H H N N O H H C H H H (Cp*Ir(DHBP)) H H C H H H C H H H C C C C C C C C C C H H H H H H N N O H O H [Ir] 2+ Ir C C C C C C H H H C H H H C H [Ir OH2] 2+ Ir C C C C C C H H H C H H H C H H H C H S21

22 H H C H H H C C C C C C C C C C H H H H H H N N O H H O H O H [Ir OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O H O H O H [Ir HOCH2OH] 2+ Ir C C C C C C H H H C H H H C H H H C H H H C S22

23 H H H C C C C C C C C C C H H H H H H N N O C H H O H H O H O H [Ir OCH2OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O C H H O H O H O H [Ir H] + Ir C C C C C C H H H C H H H C H H H S23

24 C H H H C H H H C C C C C C C C C C H H H H H H N N O H H O H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O O H [(Ir-H + )] + Ir C C C C C C H H H C H H H [(Ir-H + ) OH2] + Ir C C C C C C H H H C H H H C H H H C S24

25 H H H C H H H C C C C C C C C C C H H H H H H N N O H H O O H [(Ir-H + ) OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O H O O H [(Ir-H + ) HOCH2OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H S25

26 H H C C C C C C C C C C H H H H H H N N O C H H O H H O O H [(Ir-H + ) OCH2OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O C H H O H O O H [(Ir-H + ) OCHO] Ir C C C C C C H H H C H H H C H H H C H H S26

27 H C H H H C C C C C C C C C C H H H H H H N N O O O H C H O [(Ir-H + ) H] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O O H H [(Ir-H + ) OCH3] Ir C C C C C C H H H C H H H C H H H C H H H C H H H S27

28 C C C C C C C C C C H H H H H H N N O O O H C H H H H H H C H H H C C C C C C C C C C H H H H H H N N O O [(Ir-2H + )] Ir C C C C C C H H H C H H H C H H H C [(Ir-2H + ) OH2] Ir C C C C C C H H H C H H H C H H H C H H H C H H S28

29 H C C C C C C C C C C H H H H H H N N O H H O O [(Ir-2H + ) OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O H O O [(Ir-2H + ) HOCH2OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C S29

30 C C C C H H H H H H N N O C H H O H H O O [(Ir-2H + ) HOCH2OH] β-hydride elimination TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O C H H O H H O O [(Ir-2H + ) OCH2OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C S30

31 C C C C C C H H H H H H N N O C H H O H O O [(Ir-2H + ) OCHO] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O O O C H O [(Ir-2H + ) OCHO] β-hydride elimination TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C S31

32 C C C C H H H H H H N N O O O C O H [(Ir-2H + ) H] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O O H [(Ir-2H + ) H] attack to H2C(OH)2 TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H S32

33 H H H N N C H H H O O O H O H [(Ir-2H + ) H] attack to H2C(OH)2 (H2O) TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N C H H H O O O H O H O H H [(Ir-2H + ) H] attack to H2C(OH)2 (H2O)2 TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C S33

34 C C C C C C H H H H H H N N C H H H O O O H O H O H H O H H [(Ir-2H + ) H] attack to H2C(OH)2 (H2O)3 TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N C H H H O O O H O H O H H O H H O H H [(Ir-2H + ) H] attack to H2C(OH)O (H2O)2 TS Ir C C C C C C H H H C H S34

35 H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N C H H H O O O H O H O H O H H [(Ir-2H + ) H] attack to H2C(OH)O (H2O)3 TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N C H H H O O O H O H O H O H H S35

36 O H H [(Ir-2H + ) H] attack to OCH2 TS Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N C H H H O O O [(Ir-2H + ) OCH3] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C C C H H H H H H N N O O O C H H S36

37 H (Cp*Ir(THBPM)) O H N N [Ir] 2+ Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O H O H O H [Ir OH2] 2+ Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O H O H O H O H N N S37

38 O H H [Ir OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O H O H O H O H N N O H [Ir HOCH2OH] 2+ Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O H O H O H O H N N O H C S38

39 H H O H [Ir OCH2OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O H O H O H O H N N O C H H O H [Ir H] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O H O H O H O H S39

40 N N H H N N [Ir-H + ] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O H O [(Ir-H + ) OH2] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O H O H N N O H S40

41 H [(Ir-H + ) OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O H O H N N O H [(Ir-H + ) HOCH2OH] + Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O H O H N N O H C H H O H S41

42 [(Ir-H + ) OCH2OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O H O H N N O C H H O H [(Ir-H + ) H] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O H O H N N H S42

43 [Ir-2H + ] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O O H N N [(Ir-2H + ) OH2] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O O H N N O H H [(Ir-2H + ) OH] Ir C S43

44 C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O O H N N O H [(Ir-2H + ) HOCH2OH] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O O H N N O H C H H O H [(Ir-2H + ) OCH2OH] Ir C C C C S44

45 C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O O H N N O C H H O H [(Ir-2H + ) H] Ir C C C C C C H H H C H H H C H H H C H H H C H H H C C C C C C C C H H N N O O H O O H N N H [Ir-2H + ] Ir C C C C C C S45