Supporting Information

β-elimination Immune PC (carbene) P Iridium Complexes via Double C-H Activation: Ligand-Metal Cooperation in Hydrogen Activation. Richard J. Burford, Warren E. Piers* and Masood Parvez Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4. E-mail: wpiers@ucalgary.ca Supporting Information Experimental Details Scheme S1. Synthetic route for preparation of 1 ipr and 1 tbu. Figure S1. ORTEP illustration of 1 ipr Figure S2. Variable Temperature T 1 data for 7 ipr. Figure S3. 1 H NMR (400 MHz) spectra of 7 ipr plus D 2 Figure S4. 1 H NMR (400 MHz) spectra of 2 ipr and 2 ipr H 2 Figure S5. 13 C NMR (101 MHz) spectrum of 2 ipr. Figure S6. 1 H NMR (400 MHz) spectrum of 3 ipr. Figure S7. 13 C NMR (101 MHz) spectrum of 3 ipr. Figure S8. 1 H NMR (400 MHz) spectrum of 7 ipr. Figure S9. 1 H{ 31 P} (400 MHz) spectrum of 7 ipr (HD 3 ) C 6 D 6. Figure S10. Variable Temperature 31 P{ 1 H} (162 MHz) spectrum of 2 ipr. References S2 S10 S10 S11 S11 S12 S13 S13 S14 S14 S15 S16 S17 S 1

General Considerations. Storage and manipulation of all oxygen and moisture sensitive compounds was performed in an argon atmosphere in an IT glove box. All reactions were performed on a double manifold high vacuum line using standard techniques. 1 Passage of argon through a OxisorBW scrubber (Matheson Gas Products) removed any residual oxygen and moisture. Toluene, hexanes and tetrahydrofuran were dried and purified using a Grubbs/Dow solvent purification system, 2 and stored in 500 ml bombs over sodiumtetraglyme/benzophenone ketal. Benzene, diethylether and pentane were dried over activated sieves and subsequently vacuum transferred to 500 ml bombs containing sodium-tetraglyme/benzophenone ketal. Dichloromethane was dried over activated sieves and vacuum transferred for storage into a 500 ml bomb. d 6 -benzene was dried and stored over activated sieves and vacuum distilled prior to use. 1 H and 13 C chemical shifts were referenced to residual solvent protons and naturally abundant 13 C resonances for all deuterated solvents. Chemical shift assignments are based on 1 H, 13 C, 13 C{ 1 H}, 31 P, DQF-COSY, 1 H, 13 C-HSQC, 1 H, 13 C-HMBC NMR experiments performed on a Bruker UGI-400, DRY-400, DRX-400, RDQ-400 or CFI-600 spectrometers. NMR spectra were processed and analyzed with MestReNova (v6.0.4-5850) NMR software. X-ray crystallographic analyses were performed by Dr. Masood Parvez on a Nonius KappaCCD diffractometer with samples coated in Paratone 8277 oil (Exxon) and mounted on a glass fibre. Full crystallography details can be found in independently uploaded cif files. Iridium (III) chloride was purchased from Pressure Chemicals Inc. and used as received. [IrCl(C 8 H 14 ) 2 ] 2, 3 bis-(2-bromophenyl)methane, 4 di-tert-butylphosphine, 5 mesityl lithium etherate, 6 lithium 2,6-di-iso-propylanilide, 7 and sodium phenoxide 8 were prepared by literature methods. Ultra High Puritiy Hydrogen was purchased from Praxair and used as received. Experimental Synthesis of bis-(2-(di-iso-propylphosphino)phenyl)methane. (1 ipr ) To a flask charged with bis-(2-bromophenyl)methane (2.00g, 6.13 mmol), 120 ml of diethyl ether was added. The solution was cooled to -78 C and tert-butyllithium (1.7 M in hexane, 14.45 ml, 24.5 mmol) was added dropwise over 20 minutes. The S 2

mixture was left to stir for 3 hours and confirmed by GC-MS to be complete. Di-isopropylchlorophosphine (2.34 ml, 14.7 mmol) was then added quickly, and the solution was allowed to ward to room temperature with stirring overnight. The solution was filtered, and the solvent removed in vacuo. Acetonitrile (40 ml) and the crude product was triturated. The resulting solution was left at room temperature (2 hours) to recrystallize, then filtered. Colorless crystals were washed 3 times with acetonitrile. 1.466 g (4.49 mmol) of 1 was isolated (76% yield). 1 H NMR (400 MHz, C 6 D 6 ) δ 7.44 (m, 2H), 7.24 (s, 2H), 7.18 (m, 2H), 7.15 (m, 2H), 5.25 (t, J = 3.1 Hz, 2H), 2.06 (heptd, J = 7.0, 1.7 Hz, 4H), 1.19 (dd, J = 14.7, 7.0 Hz, 12H), 1.02 (dd, J = 11.4, 6.9 Hz, 12H). 13 C NMR (101 MHz, C 6 D 6 ): δ 149.67 (d, J = 27.8 Hz, C-P, Ar), 135.70 (d, J = 19.8 Hz, C-C-P, Ar), 133.06 (m, CH, Ar), 131.19 (m, CH, Ar), 129.19 (s, CH, Ar), 126.01 (s, CH, Ar), 39.87 (t, J = 25.9 Hz, CH 2 ), 24.92 (d, J = 13.9 Hz, CH, i Pr), 20.90 (d, J = 20.3 Hz, CH 3, i Pr), 20.02 (d, J = 11.2 Hz, CH 3, ipr). 31 P{ 1 H}-NMR (C 6 D 6 ) δ: -5 (s). HRMS (ESI) calculated for C 25 H 39 P 2 (M+) 401.25215, found 401.25334; elemental analysis calcd (%) for C 25 H 38 P 2 : C 74.97, H 9.56; found: C 74.82, H 9.34. Synthesis of bis-(2-(di-iso-propylphosphino)phenyl)methyl iridiumhydridochloride. (2 ipr ) To a flask charged with bis-(2-(di-iso-propylphosphino)phenyl)methane (0.68 g, 0.21 mmol) and chlorobis(cyclooctene)iridium(i) dimer (0.09 g, 0.10 mmol), THF (20 ml) was added. The solution was stirred for 10 minutes, then heated to reflux for 24 hours. The solvent was removed in vacuo from the resulting dark green solution, followed by addition of pentane and trituration. Filtration resulted in a beige solid in 40% yield (0.041 g, 0.066 mmol). The green filtrate from pentane was sublimed to afford 3 ipr. 1 H NMR (600 MHz, CD 2 Cl 2 ): δ 7.45 (s, 2H), 7.34 (d, J = 6.8 Hz, 2H), 7.17 (t, J = 6.8 Hz, 2H), 7.13 (d, J = 6.8 Hz, 2H), 5.75 (s, br, 1H), 2.93 (s, br, 2H), 2.77 (s, br, 2H), 1.37 (m, 6H), 1.29 (m, 12H), 0.87 (dd, J = 7.1 Hz, 6H), -28.50 (s, br, 1H). 13 C{ 1 H} NMR (151 MHz, CD 2 Cl 2 ): δ 162.55 (s, br, C-P, Ar), 137.26 (s, br, C-C-P, Ar), 130.92 (s, CH, Ar), 129.04 (s, br, CH, Ar), 126.14 (s, CH, Ar), 125.16 (s, br, CH, Ar), 28.32 (s, CH, i Pr), 26.86 (t, J = 15.7 Hz, CH, i Pr), 24.14 (s, br, CH-Ir), 19.63 (s, CH 3, i Pr), 19.52 (s, CH 3, i Pr), 19.28 (s, CH 3, i Pr), 18.91 (s, CH 3, i Pr). 31 P{ 1 H}-NMR (CD 2 Cl 2 ): δ 41 (s, br). HRMS (ESI) results show displacement of chloride by CH 3 CN, calculated for C 27 H 41 P 2 IrN (M+) S 3

632.23147, found 632.22872; elemental analysis calcd (%) for C 25 H 38 P 2 ClIr: C 47.80, H 6.10; found: C 46.99, H 5.90. Synthesis of bis-(2-(di-iso-propylphosphino)phenyl)methylidene iridium chloride. (3 ipr ) To a bomb charged with bis-(2-(di-iso-propylphosphino)phenyl)methane (0.100g, 0.306 mmol) and chlorobis(cyclooctene)iridium(i) dimer (0.105g, 0.117 mmol), 30 ml of THF was added. The initially clear orange solution was then heated to 120 C for 40 hours to afford a dark green solution. The solvent was removed under vacuum followed by addition of pentane and trituration. Filtration and subsequent washes with pentane afforded a dark green solid (0.055g, 0.089 mmol). Purification can be achieved through sublimation. 3 ipr is also produced through sublimation of solid 2 at 220 C under dynamic vacuum in 77% isolated yield. 1 H NMR (400 MHz, C 6 D 6 ) δ 8.02 (d, J = 7.8 Hz, 2H), 7.91 (t, J = 7.3 Hz, 2H), 7.02 (dt, J = 6.7, 3.1 Hz, 2H), 6.39 (t, J = 7.6 Hz, 2H), 3.03 (ttd, J = 11.7, 6.8, 6.0, 2.4 Hz, 4H), 1.52 (dd, J = 7.2 Hz, 12H), 1.24 (dd, J = 7.2 Hz, 6H). 13 C{ 1 H} NMR (101 MHz, C 6 D 6 ): δ 199.70 (t, J = 3.9 Hz, C=Ir), 177.44 (app. t, J = 17.6 Hz, C-C-P, Ar), 137.90 (app. t, J = 18.8 Hz, C-P, Ar), 134.88 (s, CH, Ar), 133.09 (s, CH, Ar), 127.84 (s, CH, Ar), 123.74 (app. t, J = 6.6 Hz, CH, Ar), 24.97 (app. t, J = 13.6 Hz, CH, i Pr), 20.40 (s, CH 3, i Pr), 19.58 (s, CH 3, i Pr). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ): δ 46 (s); HRMS (ESI) calculated for C 25 H 36 P 2 ClIr (M+) 625.16594, found 625.1629; elemental analysis calcd (%) for C 25 H 36 P 2 ClIr: C47.95, H 5.79; found: C 47.62, H 5.76. Synthesis of bis-(2-(di-iso-propylphosphino)phenyl)methylidene iridium mesityl. (4 ipr ) To a THF solution of 3 ipr (0.011g, 0.017 mmol), a THF solution of mesityl lithium (0.003g, 0.024 mmol) was added dropwise and stirred under argon for 2 hours. The solution color changed from dark green to deep red over this time. The solvent was removed in vacuo and hexane was added. Lithium chloride was removed three successive triturations and solvent removal, followed by a final addition of hexane and filtration with subsequent solvent removal in vacuo. Product 4 ipr was isolated as a red semisolid in 90% yield. 1 H NMR (400 MHz, C 6 D 6 ): δ 8.00 (d, J = 7.9 Hz, 2H), 7.89 (t, J = 7.3 Hz, 2H), 6.97 (dd, J = 6.7, 3.2 Hz, 2H), 6.92 (s, 2H), 6.34 (t, J = 7.5 Hz, 2H), 2.97 (m, 4H), 2.43 (s, 3H), 2.00 (s, 6H), 1.22 (dd, J = 7.0 Hz, 12H), 1.07 (dd, J = 7.3 Hz, 12H). 13 C{ 1 H} S 4

NMR (101 MHz, C 6 D 6 ): δ 201.30 (t, J = 5.1 Hz C=Ir), 177.07 (app. t, J = 17.5 Hz, C-P, Ar), 158.47 (app. t, J = 8.2 Hz, C-C-P, Ar), 145.31 (app. t, J = 1.4 Hz, CCH 3, Mes), 140.23 (t, J = 19.2 Hz, C-Ir, Mes), 134.52 (d, J = 10.3 Hz, CH, Ar), 133.15 (d, J = 10.5 Hz, CH, Ar), 131.60 (s, CH, Mes), 129.38 (s, CH, Mes), 126.88 (s, CH, Ar), 124.26 (m, CH, Ar), 28.77 (s, CH 3, Mes), 25.04 (app. t, J = 13.8 Hz, CH, i Pr), 21.39 (s, CH 3, Mes), 20.01 (app. t, J = 2.0 Hz, CH 3, i Pr), 18.56 (s, CH 3, i Pr). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ): δ 43 (s). elemental analysis calcd (%) for C 34 H 47 P 2 Ir: C 57.52, H 6.67; found: C 57.96, H 6.36. Synthesis of bis-(2-(di-iso-propylphosphino)phenyl)methylidene iridium 2,6- diisopropylanilide. (5 ipr ) To a solution of 3 ipr (0.050g, 0.080 mmol) in 2 ml THF, cooled to -30 C over 0.5 hours, a solution of lithium-2,6-diisopropylanilide (0.017g, 0.093 mmol) in 2 ml THF at -30 C was added dropwise. The solution instantly displayed a deep magenta colour. The reaction was stirred under argon for 3 hours, followed by removal of THF in vacuo. Residue was dissolved in hexane, triturated and filtered. Removal of solvent in vacuo resulted in a pink semisolid in 84 % yield (0.052g). 1 H NMR (400 MHz, C 6 D 6 ): δ 8.06 (d, J = 7.9 Hz, 2H), 7.66 (t, J = 7.4 Hz, 2H), 7.24 (d, J = 7.6 Hz, 2H), 7.08 (dd, J = 7.6, 3.8 Hz, 2H), 7.03 (t, J = 7.9 Hz, 1H), 6.57 (t, J = 7.7 Hz, 2H), 5.91 (t, J = 4.6 Hz, 1H, NH), 3.88 (p, J = 6.7 Hz, 2H), 2.66 (ttd, J = 9.4, 6.6, 3.9 Hz, 4H), 1.27 (d, J = 6.8 Hz, 12H), 1.16 (m, 24H). 13 C NMR (101 MHz, C 6 D 6 ): δ 196.32 (t, J = 4.1 Hz, C=Ir), 176.65 (app. t, J = 17.8 Hz, C-P, Ar), 160.13 (app. t, J = 3.1 Hz, C-C-P, Ar), 140.73 (s, C- i Pr, Ar NHdipp), 136.36 (d, J = 21.4 Hz, C-N, Ar, NHdipp), 133.57 (s, CH, Ar), 132.22 (s, CH, Ar), 124.21 (app. t, J = 3.0 Hz, CH, Ar), 123.13 (s, CH, Ar, NHdipp), 122.48 (s, CH, Ar, NHdipp), 122.12 (s, CH, Ar, NHdipp), 121.51 (app. t, J = 6.8 Hz, CH, Ar), 28.19 (s, CH, i Pr, NHdipp), 28.07 (s, CH, i Pr, NHdipp), 24.03 (app. t, J = 12.9 Hz, CH, i Pr), 23.72 (s, CH 3, i Pr, NHdipp), 22.62 (s, CH 3, i Pr), 19.46 (s, CH 3, i Pr), 18.80 (s, CH 3, i Pr). 31 P NMR (162 MHz, C 6 D 6 ) δ 43.65 (s). elemental analysis calcd (%) for C 37 H 54 NP 2 Ir: C 57.94, H 7.10, N 1.83; found: C 58.40, H 7.25, N 1.78. Synthesis of bis-(2-(di-iso-propylphosphino)phenyl)methylidene iridium phenoxide. (6 ipr ) S 5

To a solution of 3 ipr (0.031g, 0.049 mmol) in 2ml THF, cooled to -30 C over 0.5 hours, a solution of sodium phenoxide (0.011 g, 0.095 mmol) in 2 ml THF at -30 C was added dropwise. The solution remained deep green in color. The reaction was cooled to - 78 C and allowed to warm to room temperature under a dynamic flow of argon over 12 hours. The solvent was removed in vacuo and pentane was added (10 ml). The pentane solution was stirred for 0.5 hours, and allowed to warm to room temperature, at which point, the solution was filtered. The off-white precipitate was washed three times with pentane and the solvent removed in vacuo to afford a green semisolid (0.020 g, 59% isolated yield). 1 H NMR (400 MHz, C 6 D 6 ): δ 7.97 (d, J = 7.9 Hz, 2H), 7.85 (t, J = 7.4 Hz, 2H), 7.25 (t, J = 7.6 Hz, 2H, OPh), 7.02 (dt, J = 6.5, 3.2 Hz, 2H), 6.73 (t, J = 7.3 Hz, 1H, OPh), 6.60 (s, br, 2H, OPh), 6.45 (t, J = 7.6 Hz, 2H), 2.77 (pt, J = 7.0, 2.1 Hz, 2H), 1.28 (dd, J = 7.6 Hz, 12H), 1.19 (dd, J = 7.2 Hz, 12H). 13 C NMR (101 MHz, C 6 D 6 ): δ 208.47 (t, J = 3.1 Hz, C=Ir), 178.06 (app. t, J = 17.1 Hz, C-C-P, Ar), 137.28 (app. t, J = 19.6 Hz, C-P, Ar), 134.90 (s, CH, Ar), 133.08 (s, CH, Ar), 129.45 (s, CH, OPh), 126.65 (m, CH, Ar), 122.79 (s, CH, OPh), 121.78 (app. t, J = 6.6 Hz, CH, Ar), 115.87 (s, CH, OPh), 24.71 (app. t, J = 13.2 Hz, CH, i Pr), 19.87 (app. t, J = 2.5 Hz, CH 3, i Pr), 19.38 (s, CH 3, i Pr). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ): δ 48 (s). elemental analysis calcd (%) for C 31 H 41 OP 2 Ir: C 54.45, H 6.04; found: C 55.30, H 6.37. Synthesis of bis-(2-(di-iso-propylphosphino)phenyl)methyl iridium bis dihydrogen. (7 ipr ) To a degassed C 6 D 6 solution of 4 ipr, (0.015 g, 0.02 mmol), 1 atmosphere of dihydrogen was added. The solution was mixed thoroughly and after 10 minutes the deep red solution had become pale orange, and mesitylene was observed in the 1 H-NMR spectrum. This complex is stable in solution, but decomposes upon removal of solvent. 1 H NMR (400 MHz, C 6 D 6 ) δ: 7.74 (d, J = 7.7 Hz, 2H), 7.10 (m, 4H), 6.92 (t, J = 7.4 Hz, 2H), 6.18 (s, br, 1H), 1.87 (m, 2H), 1.80 (m, 2H), 1.17 (dd, J = 7.5 Hz, 6H), 1.05 (dd, J = 7.7 Hz, 6H), 0.90 (dd, J = 7.2 Hz, 6H), 0.83 (dd, J = 7.4 Hz, 6H), -9.79 (t, J = 10.4 Hz, 4H). 13 C NMR (101 MHz, C 6 D 6 ) δ 163.77 (app. t, J = 13.5 Hz, C-C-P, Ar), 141.85 (app. t, J = 23.9 Hz, C-P, Ar), 130.87 (d, J = 10.6 Hz, CH, Ar), 127.05 (app. t, J = 6.6 Hz, CH, Ar), 124.52 (app. t, J = 3.6 Hz, CH, Ar), 28.52 (app. t, J = 15.2 Hz, CH, i Pr), 24.45 (app. S 6

t, J = 17.3 Hz, CH, i Pr), 20.39 (s, CH 3, i Pr), 19.99 (s, CH 3, i Pr), 18.64 (s, CH 3, i Pr). 31 P NMR (162 MHz, C 6 D 6 ) δ 54.57 (s). Synthesis of bis-(2-(di-tert-butylphosphino)phenyl)methane. (1 tbu ) This synthesis is a modified version of that reported by Stradiotto and coworkers, for the installation of aryl phosphines ortho in anilines. 9 Palladium (8.0 mg, 0.036 mmol) was placed in a vial and dissolved in toluene (1 ml). The solution was added to a 50 ml bomb charged with 1,1 -bis-(diphenylphosphino)ferrocene (DPPF) (20.0 mg, 0.036 mmol) and the mixture was stirred for 30 min. Independently, sodium tert-butoxide (100.0 mg, 1.4 mmol) was suspended in 1 ml of toluene and di-tert-butylphosphine (0.26 µl, 1.4 mmol) was added via syringe. Bis-(2-bromophenyl)methane (226.0 mg, 0.69 mmol) was dissolved in 1 ml toluene and added to the bomb, in addition to the palladium acetate/ DPPF solution. The bomb was sealed and heated to 110 C for 48 hours. The reaction was determined to be complete by removal of aliquots for 31 P NMR until all di-tert-butylphosphine had been consumed. The reaction mixture was cooled to room temperature and passed through a plug of silica followed by a wash with dichloromethane (10 ml). The solvent was removed from the filtrate to yield an orange oil. Purification was achieved through recrystalization in acetonitrile with addition of a small amount of lithium chloride (1 mg) in 72% yield. 1 H NMR (400 MHz, C 6 D 6 ): δ 7.79 (m, 2H), 7.08 (m, 6H), 5.29 (t, J = 3.0 Hz, 2H), 1.23 (d, J = 11.6 Hz, 36H). 13 C{ 1 H} NMR (101 MHz, C 6 D 6 ): δ 150.60 (dd, J = 29.7, 2.1 Hz, C-P, Ar), 137.04 (d, J = 26.2 Hz, C-C-P, Ar), 135.80 (d, J = 2.8 Hz, CH, Ar), 131.59 (d, J = 6.6 Hz, CH, Ar), 129.34 (s, CH, Ar), 125.21 (s, CH, Ar), 41.49 (t, J = 29.7 Hz, CH 2 ), 33.03 (d, J = 24.6 Hz, C(CH 3 ) 3, t Bu), 31.28 (d, J = 15.7 Hz, CH 3, t Bu). 31 P NMR (162 MHz, C 6 D 6 ): δ 15.97. HRMS (ESI) calculated for C 29 H 46 P 2 (M+) 457.31475, found 457.31952; elemental analysis calcd (%) for C 29 H 46 P 2 : C 76.28, H 10.15; found: C 76.08, H 9.97. Synthesis of bis-(2-(di-tert-butylphosphino)phenyl)methyl iridiumhydridochloride. (2 tbu ) To a flask charged with 1 tbu (0.68 g, 0.21 mmol) and chlorobis(cyclooctene)iridium(i) dimer (0.09 g, 0.10 mmol), THF (20 ml) was added. The solution was stirred for 10 minutes, then heated to reflux for 24 hours. The solvent S 7

was removed in vacuo from the resulting dark brown solution, followed by addition of pentane and trituration. Filtrate results in a brown solid in 32% yield (0.041 g, 0.066 mmol). The brown filtrate from pentane was sublimed to make 3 tbu, to which 1 atm of dihydrogen is added to afford pure 2 tbu. 1 H NMR (400 MHz, C 6 D 6 ): δ 7.67 (d, J = 7.9 Hz, 2H), 7.60 (dd, J = 6.7, 3.0 Hz, 2H), 7.01 (t, J = 7.5 Hz, 2H), 6.93 (t, J = 7.3 Hz, 2H), 6.20 (s, 1H), 1.51 (m, 18H), 1.40 (m, 18H), -36.80 (t, J = 12.0 Hz, 1H). 13 C{ 1 H} NMR (101 MHz, C 6 D 6 ): δ 163.45 (app. t, J = 14.1 Hz, C-CH-Ir, Ar), 137.53 (app. t, J = 20.1 Hz, C-P, Ar), 134.14 (s, CH, Ar), 128.89 (s, CH, Ar), 126.51 (app. t, J = 6.5 Hz, CH, Ar), 124.60 (app. t, J = 3.3 Hz, CH, Ar), 39.93 (app. t, J = 9.4 Hz, C(CH 3 ) 4, t Bu), 37.13 (app. t, J = 11.4 Hz, C(CH 3 ) 3, t Bu), 31.60 (app. t, J = 2.6 Hz, CH 3, t Bu), 30.50 (app. t, J = 2.8 Hz, CH 3, t Bu), 22.45 (s, CH-Ir). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ): δ 65.78 (s). HRMS (ESI) results show displacement of chloride by CH 3 CN, calculated for C 31 H 49 P 2 IrN (M+) 690.29712, found 690.29542; elemental analysis calcd (%) for C 29 H 46 P 2 ClIr: C 50.90, H 6.78; found: C 51.74, H 6.48. Synthesis of bis-(2-(di-tert-butylphosphino)phenyl)methylidene iridium chloride. (3 tbu ) A benzene solution of 2 tbu (103 mg, 0.15 mmol) was cooled to -78 C and pumped under dynamic vacuum and allowed to warm slowly. After 3 hours, a brown residue resulted which was heated to 220 C under dynamic vacuum overnight. The next day, the walls of the sublimation vessel were coated with green semisolid which was isolated in 80 % yield. 1 H NMR (400 MHz, C 6 D 6 ): δ 7.92 (t, J = 7.6 Hz, 4H), 7.44 (dd, J = 7.0, 3.4 Hz, 2H), 6.35 (t, J = 7.6 Hz, 2H), 1.63 (m, 36H). 13 C { 1 H} NMR (101 MHz, C 6 D 6 ): δ 197.54 (t, J = 2.9 Hz, C=Ir), 178.15 (app. t, J = 17.3 Hz, C-P, Ar), 136.84 (s, CH, Ar), 136.58 (app. t, J = 16.7 Hz, C-C-P, Ar), 132.51 (s, CH, Ar), 127.54 (app. t, J = 2.8 Hz, CH, Ar), 125.03 (app. t, J = 6.7 Hz, CH, Ar), 36.76 (t, J = 9.6 Hz, C(CH 3 ) 3, t Bu), 31.92 (app. t, J = 3.1 Hz, CH 3, t Bu). 31 P { 1 H} NMR (162 MHz, C 6 D 6 ): δ 58.32 (s). HRMS (ESI) results show displacement of chloride by CH 3 CN, calculated for C 31 H 47 P 2 IrN (M+) 686.27842, found 686.2758; calculated for C 29 H 44 IrP 2 (M+) 645.25187, found 645.2492; elemental analysis calcd (%) for C 29 H 44 P 2 ClIr: C 51.05, H 6.50; found: C 51.47, H 5.96. S 8

Synthesis of bis-(2-(di-tert-butylphosphino)phenyl)methylidene iridium phenoxide. (6 tbu ) To a flask charged with 3 tbu (45.0 mg, 0.066 mmol) 3 ml of basified, filtered, cooled to -30 C THF was added. In a separate vial, sodium phenoxide (9.0 mg, 0.078 mmol) was dissolved in the same THF (2 ml) and added dropwise to the flask. The resultant green solution was stirred under argon and allowed to warm to room temperature overnight. After 24 hours, the solvent was removed in vacuo, hexane was added and the solution was triturated. The solvent was removed in vacuo, and this process was repeated three times. Hexane was added a fourth time, and the solution was triturated and filtered. The precipitate was washed three times with hexane and the solvent was removed from the filtrate in vacuo. A green semisolid was isolated in 65 % yield. 1 H NMR (400 MHz, C 6 D 6 ): δ 7.87 (d, J = 8.0 Hz, 2H), 7.85 (t, J = 7.4 Hz, 2H), 7.42 (dt, J = 6.6, 3.0 Hz, 2H), 7.33 (m, 2H), 6.66 (t, J = 7.2 Hz, 2H, OPh), 6.44 (dt, J = 7.4, 3.4 Hz, 4H, OPh), 1.49 (app. t, J = 6.8 Hz, 36H). 13 C NMR (101 MHz, C 6 D 6 ): δ 204.88 (t, J = 2.8 Hz, C=Ir), 178.81 (app. t, J = 16.8 Hz, C-P), 171.30 (s, C-C-P), 136.42 (s, CH, Ar), 132.57 (s, CH, Ar), 129.53 (s, CH, OPh), 126.28 (app. t, J = 2.9 Hz, CH, Ar), 122.78 (app. t, J = 6.5 Hz, CH, Ar), 122.17 (s, CH, OPh), 114.55 (s,ch, OPh), 35.45 (app. t, J = 9.3 Hz, C(CH 3 ) 3, t Bu), 31.45 (app. t, J = 3.4 Hz, CH 3, t Bu). 31 P NMR (162 MHz, C 6 D 6 ): δ 61.17 (s). elemental analysis calcd (%) for C 35 H 49 P 2 OIr: C 56.81, H 6.67; found: C 56.80, H 6.50. Synthesis of bis-(2-(di-tert-butylphosphino)phenyl)methyl iridium bis dihydrogen. (7 tbu ) To a degassed C 6 D 6 solution of 6 tbu, (15 mg, 0.02 mmol), 1 atmosphere of dihydrogen was added. The solution was mixed thoroughly and after 3 hours the deep green solution had become pale yellow, and phenol is observed in the 1 H-NMR spectrum. This complex is stable in solution, but decomposes upon removal of solvent. 1 H NMR (400 MHz, C 6 D 6 ) δ 7.73 (d, J = 8.1 Hz, 2H), 7.61 (m, 2H), 7.10 (t, J = 7.7 Hz, 2H), 6.92 (t, J = 7.5 Hz, 2H), 5.86 (s, 1H), 1.37 (m, 36H), -9.27 (t, J = 9.9 Hz, 4H). 13 C NMR (101 MHz, C 6 D 6 ): δ 164.52 (app. t, J = 13.9 Hz, C-C-P, Ar), 141.28 (app. t, J = 20.3 Hz, C-P, Ar), 133.00 (s, CH, Ar), 127.69 (app. t, J = 6.5 Hz, CH, Ar), 123.76 (app. t, J = 3.5 Hz, CH, Ar), 36.03 (app. t, J = 11.1 Hz, CH, Ar), 34.32 (dt, J = 171.9 Hz, J = 13.0 Hz, S 9

C(CH 3 ) 3, t Bu), 30.68 (d, J = 152.9 Hz, CH 3, t Bu), 27.68 (s, CH-Ir, alkyl). 31 P NMR (162 MHz, C 6 D 6 ) δ 70.59 (s). 1) t BuLi 2) i Pr 2 PCl Br 1) i PrMgCl. LiCl I 2) O Br Br HI HOAc OH Br Br Br t Bu 2 PH NaOtBu 5 mol% PdOAc 5 mol% DPPF Tol, 110 o C P i Pr 2 P i Pr 2 P t Bu 2 P t Bu 2 Scheme S1. Synthetic route for preparation of 1 ipr and 1 tbu. Figure S1. ORTEP illustration of 1 ipr, with thermal ellipsoids drawn at the 50% probability level (hydrogen atoms have been omitted for clarity). S 10

Figure S2. Variable Temperature T 1 data for 7 ipr. 1 atm of H 2 gas, collected on CFI-600 NMR Spectrometer. 10 D i Pr 2 P Ir D 4 P i Pr 2 1) degassed 2) D 2 added H i Pr 2 P Ir P i Pr 2 H 4 Figure S3. 1 H NMR (400 MHz) spectra of 7 ipr C 6 D 6 taken after removal of H2 atmosphere and 1 atm D 2 added, (Red = 7 ipr, green = 5 minutes after D 2 addition, blue = 20 hours after D 2 addition). S 11

H i Pr 2 P Ir P i Pr 2 H Cl H i Pr 2 P Ir P i Pr 2 H H 2 Cl Figure S4. 1 H NMR (400 MHz) spectra of 2 ipr (top) and 2 ipr H 2 (bottom) in CD 2 Cl 2 at 235 K. S 12

H i Pr 2 P Ir P i Pr 2 H Cl Figure S5. 13 C NMR (101 MHz) spectrum of 2 ipr in CD 2 Cl 2. i Pr 2 P Ir P i Pr 2 Cl Figure S6. 1 H NMR (400 MHz) spectrum of 3 ipr in C 6 D 6. S 13

i Pr 2 P Ir P i Pr 2 Cl Figure S7. 13 C NMR (101 MHz) spectrum of 3 ipr in C 6 D 6. H i Pr 2 P Ir P i Pr 2 H 4 Figure S8. 1 H NMR (400 MHz) spectrum of 7 ipr in C 6 D 6. S 14

Figure S9. 1 H{ 31 P} (400 MHz) spectrum of 7 ipr (HD 3 ) C 6 D 6. 97% deuteration. S 15

Figure S10. (Top) Varible temperature 31 P NMR spectra of 2 ipr in Toluene-d 8. 1) 308K, 2) 298K, 3) 288K, 4) 278K, 5) 268K, 6) 258K, 7) 248K, 8) 238K, 9) 228K, 10) 218K, 11) 208K, 12) 198K. (Bottom) 31 P NMR spectrum of 2 ipr at 198K in Toluene-d 8. S 16

References. (1) Burger, B. J. J. E. B. Experimental Organometallic Chemistry; American Chemical Society: Washington D.C., 1987. (2) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.; Timmers, F. J. Organometallics 1996, 15, 1518. (3) Herde, J. L.; Lambert, J. C.; Senoff, C. V. Inorganic Syntheses 1974, 15, 18. (4) Wood, T. K.; Piers, W. E.; Keay, B. A.; Parvez, M. Angewandte Chemie International Edition 2009, 48, 4009. (5) Hoffmann, H.; Schellenbeck, P. Chemische Berichte 1966, 99, 1134. (6) Zigler, S. S.; Johnson, L. M.; West, R. Journal of Organometallic Chemistry 1988, 341, 187. (7) Bryson, N.; Youinou, M. T.; Osborn, J. A. Organometallics 1991, 10, 3389. (8) Liang, L.- C.; Chien, P.- S.; Lee, P.- Y.; Lin, J.- M.; Huang, Y.- L. Dalton Transactions 2008, 3320. (9) Lundgren, R. J.; Sappong- Kumankumah, A.; Stradiotto, M. Chemistry A European Journal 2010, 16, 1983. (10) Hamilton, D. G.; Crabtree, R. H. Journal of the American Chemical Society 1988, 110, 4126. S 17