A Highly Reactive Scandium Phosphinoalkylidene Complex: C H and H H Bonds Activation

Transcription

1 A Highly Reactive Scandium Phosphinoalkylidene Complex: C H and H H Bonds Activation Weiqing Mao, Li Xiang, Carlos Alvarez Lamsfus, Laurent Maron,*, Xuebing Leng, Yaofeng Chen*, State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai , P. R. China LPCNO, CNRS & INSA, Université Paul Sabatier, 135 Avenue de Rangueil, Toulouse, France Supporting Information Contents 1. General...S2 2. Synthesis of Li[CH(SiMe 3 )PPh 2 ](THF) and S2 3. The isotopic labeling experiments...s8 4. X-ray crystallography for S9 5. Molecular structures of 1, 3, 4 and 7...S13 6. NMR spectrum of Li[CH(SiMe 3 )PPh 2 ](THF) and S15 7. The reversible process between 2 and 3...S H and 2 H NMR spectrum of the reaction solution of 2 with pyridine-d 5...S H, 1 H- 1 H gcosy and 2 H NMR spectrum of the product of the reaction of 2, D 2 and 1-hexene..... S H 1 H NOESY spectrum of 3...S H NMR spectral monitoring result of the metalation of 2 in C 6 D 6 at three different concentrations...s Computation details...s References...S85 S1

2 General. All operations were carried out under an atmosphere of argon using Schlenk techniques or in a nitrogen filled glovebox. Toluene, tetrahydrofuran, hexane, C 6 D 6 and THF-d 8 were dried over Na/K alloy, transferred under vacuum, and stored in the glovebox. CH 2 (SiMe 3 )PPh 2 and [LSc(Me)Cl] (L = [MeC(NDIPP)CHC(Me)(NDIPP)] -, DIPP = 2,6-( i Pr) 2 C 6 H 3 ) were synthesized as reported. 1,2 Pyridine, 1,3-dimethylpyrazole and 1-hexene were dried over activated 4 Å molecular sieves and degassed by three freeze-pump-thaw cycles before use. 4-dimethylamino pyridine was purified by sublimation. The highly pure H 2 (>99.9%) was further dried by passing through the activated 4 Å molecular sieves. 1 H, 13 C{ 1 H} and 31 P{ 1 H} NMR spectra were recorded on a Varian 400 MHz, an Agilent 400 MHz, an Agilent 500 MHz or an Agilent 600 MHz spectrometer. Chemical shifts were reported in δ units with references to the residual solvent resonance of the deuterated solvents for proton and carbon chemical shifts, to external H 3 PO 4 (85%) for phosphorus chemical shifts. The assignment of 1 H and 13 C{ 1 H} resonances was assisted with gcosy, ghsqc and ghmbc spectra. Elemental analysis was performed by the Analytical Laboratory of Shanghai Institute of Organic Chemistry. Li[CH(SiMe 3 )PPh 2 ](THF): Li[CH(SiMe 3 )PPh 2 ](THF) was synthesized by using the method reported by Peterson. 3 n-butyllithium (2.5 M in hexane, 8.82 mmol, 3.5 ml) was added to CH 2 (SiMe 3 )PPh 2 (2.40 g, 8.82 mmol) in 15 ml of THF at 0 o C. The reaction solution was allowed to warm to room temperature and stirred at room temperature for 2 h. The volatiles of the solution were removed under vacuum, the residue was washed with 5 2 ml of hexane and dried under vacuum to give Li[CH(SiMe 3 )PPh 2 ](THF) as a white solid (1.64 g, 53% yield). 1 H NMR (400 MHz, C 6 D 6, 25 o C): δ 7.63 (t, 3 J H-H = 7.4 Hz, 4H, o-phh of PPh 2 ), 7.16 (t, 3 J H-H = 7.3 Hz, overlapped with the residual solvent resonance of the deuterated solvent, m-phh of PPh 2 ), 7.07 (t, 3 J H-H = 7.2 Hz, 2H, p-phh of PPh 2 ), 3.42 (m, 4H, THF-H), 1.17 (m, 4H, THF-H), 0.29 (s, 9H, SiMe 3 ), 0.08 (s, 1H, PCHSi). 13 C{ 1 H}NMR (100 MHz,C 6 D 6, 25 o C): δ (i-phc of PPh 2 ), (d, 2 J P-C = 15.3 Hz, o-phc of PPh 2 ), (d, 3 J P-C = 6.7 Hz, m-phc of PPh 2 ), ( p-phc of PPh 2 ), 68.9 (THF-C), 25.3 (THF-C), 5.8 S2

3 (d, 1 J P-C = 26.8 Hz, PCHSi), 4.6 (d, 3 J P-C = 5.8 Hz, SiMe 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6, 25 o C): δ Anal. Calcd for C 20 H 28 LiOPSi: C 68.55; H Found: C 68.31; H : [LSc(Me)Cl] (1.86 g, 3.63 mmol) and Li[CH(SiMe 3 )PPh 2 ](THF) (1.27 g, 3.63 mmol) were mixed in 10 ml of toluene. After stirring at room temperature for 0.5 h, the precipitate was moved by filtration. The volatiles of the solution were removed under vacuum, the residue was washed with 5 2 ml of hexane and dried under vacuum to give 1 as a pale yellow solid (1.79 g, 66% yield). 1 H NMR (400 MHz, C 6 D 6, 25 o C): δ 7.26 (m, 4H, o-phh of PPh 2 ), 7.17 (d, 3 J H-H = 7.6 Hz, overlapped with the residual solvent resonance of the deuterated solvent, m-arh of DIPP), 7.13 (t, 3 J H-H = 7.6 Hz, 2H, p-arh of DIPP), 6.99 (m, 6H, m-phh of PPh 2 and p-phh of PPh 2 ), 6.94 (d, 3 J H-H = 7.3 Hz, 2H, m-arh of DIPP), 5.11 (s, 1H, MeC(N)CH), 3.78 (sept, 3 J H-H = 6.8 Hz, 2H, CHMe 2 ), 2.83 (sept, 3 J H-H = 6.8 Hz, 2H, CHMe 2 ), 1.62 (s, 6H, CMe), 1.52 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 1.29 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 0.95 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 0.85 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 0.64 (s, 3H, ScMe), (s, 9H, SiMe 3 ), (s, 1H, PCHSi). 13 C{ 1 H}NMR (100 MHz, C 6 D 6, 25 o C): δ (imine C), (i-arc of DIPP), 143.4, (o-arc of DIPP), (d, 1 J P-C = 6.3 Hz, i-phc of PPh 2 ), (d, 2 J P-C = 14.7 Hz, o-phc of PPh 2 ), (d, 4 J P-C = 1.4 Hz, p-phc of PPh 2 ), (d, 3 J P-C = 8.3 Hz, m-phc of PPh 2 ), (p-arc of DIPP), 124.7, (m-arc of DIPP), 97.2 (MeC(N)CH), 46.8 (d, 1 J P-C = 54.8 Hz, PCHSi), 34.1 (br, ScMe), 29.0, 28.9(CHMe 2 ), 26.5, 24.8, 24.3, 23.4 (CHMe 2 and CMe), 3.63 (d, 3 J P-C = 2.0 Hz, SiMe 3 ). 31 P{ 1 H}NMR (162 MHz, C 6 D 6, 25 o C): δ Anal. Calcd for C 46 H 64 N 2 PScSi: C 73.76; H 8.61; N Found: C 73.83; H 8.99; N : 1 (473 mg, 0.63 mmol) was dissolved in 10 ml of THF. After standing at 50 o C for 14 h, the volatiles of the reaction solution were removed under vacuum, the residue was washed with 3 2 ml of hexane and dried under vacuum to give 2 as an orange solid (318 mg, 63% yield). 1 H NMR (400 MHz, THF-d 8, 25 o C): δ 7.23 (m, 6H, Ar-H), S3

4 6.88 (m, 10H, Ph-H), 5.07 (s, 1H, MeC(N)CH), 3.61 (m, 4H, THF-H), 3.42 (sept, 3 J H-H = 6.7 Hz, 2H, CHMe 2 ), 3.01 (sept, 3 J H-H = 6.7 Hz, 2H, CHMe 2 ), 1.77 (m, 4H, THF-H), 1.65 (s, 6H, CMe), 1.53 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 1.28 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 1.23 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 1.16 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), (s, 9H, SiMe 3 ). 13 C{ 1 H} NMR (100 MHz, THF-d 8, 25 o C): δ (imine C), (d, 1 J P-C = 103 Hz, PCSi), (d, 1 J P-C = 6.0 Hz, i-phc of PPh 2 ), (i-arc of DIPP), 142.9, (o-arc of DIPP), (d, 2 J P-C = 12.9 Hz, o-phc of PPh 2 ), (d, 3 J P-C = 8.0 Hz, m-phc of PPh 2 ), (p-arc of DIPP), (d, 4 J P-C = 1.3 Hz, p-phc of PPh 2 ), 124.9, (m-arc of DIPP), 97.1 (MeC(N)CH), 68.0 (THF-C), 29.7, 29.2 (CHMe 2 ), 26.2 (THF-C), 25.6, 25.5, 25.2, 24.9, 24.8, 24.4 (CHMe 2 and CMe), 4.7 (SiMe 3 ). 31 P{ 1 H}NMR (162 MHz, THF-d 8, 25 o C): δ Anal. Calcd for C 49 H 68 N 2 OPScSi: C 73.10; H 8.51; N Found: C 73.07; H 8.29; N : 2 (100 mg, 0.12 mmol) was dissolved in 6 ml of toluene at room temperature. The volatiles of the solution were removed under vacuum, and this operation was repeated for three times to remove the THF from 2. 1 ml of hexane was added to the residue. After standing at -35 o C for 1 day, the solid was isolated, washed with 0.5 ml of cold hexane and dried under vacuum to give 3 as a yellow solid (63 mg, 69% yield). There are two isomers in 5:1 ratio; these two isomers are related to the stereogenic tertiary carbon of the isopropyl group bound to the scandium ion. The 1 H 1 H NOESY spectrum revealed that the major and minor diastereomers have the H and CH 3 on the tertiary carbon pointing towards the backbone of Nacnac ligand, respectively, and the major diastereomer has been subjected to XRD. The 1 H NMR spectral monitoring of the reaction in C 6 D 6 showed that the ratio of two isomers is constant during the reaction. 1 H NMR (500 MHz, C 6 D 6, 25 o C): δ (m, 0.33H, Ar-H), (m, 1.67H, Ar-H), 7.42 (d, 3 J H-H = 7.5 Hz, 0.84H, Ar-H), (m, 1H, Ar-H), (m, overlapped with the residual solvent resonance of the deuterated solvent, Ar-H), 6.82 (d, 3 J H-H = 7.5 Hz, 0.84H, Ar-H), 5.14 (s, 0.84H, MeC(N)CH), 5.10 (s, 0.16H, MeC(N)CH), (m, 0.33H, CHMe 2 and S4

5 CH 2 CH(CH 3 )), 3.56 (sept, 3 J H-H = 6.8 Hz, 0.84H, CHMe 2 ), (m, 1.67H, CHMe 2 and CH 2 CH(CH 3 )), 3.21 (sept, 3 J H-H = 6.8 Hz, 0.16H, CHMe 2 ), (m, 1H, CHMe 2 ), 1.81 (s, 0.48H, CMe), 1.72 (s, 2.52H, CMe), 1.64 (s, 2.52H, CMe), 1.61 (s, 0.48H, CMe), 1.55 (m, CHMe 2 ), 1.50 (d, 3 J H-H = 7.2 Hz, 0.48H, CHMe 2 ), 1.44 (dd, 2 J H-H = 12.4 Hz, 3 J H-H = 4.7 Hz, 0.84H, CH 2 CH(CH 3 )), 1.32 (d, 3 J H-H = 6.9 Hz, 2.52H, CHMe 2 ), 1.25 (d, 3 J H-H = 6.8 Hz, 0.48H, CHMe 2 ), 1.19 (m, CHMe 2 ), 0.91 (d, 3 J H-H = 6.8 Hz, 2.52H, CHMe 2 ), 0.89 (d, 3 J H-H = 6.8 Hz, 0.48H, CHMe 2 ), 0.86 (br t, 0.84H, CH 2 CH(CH 3 )), 0.83 (d, 3 J H-H = 6.9 Hz, 0.48H, CHMe 2 ), 0.77 (d, 3 J H-H = 6.9 Hz, 2.52H, CHMe 2 ), (s, 7.56H, SiMe 3 ), (s, 1.44H, SiMe 3 ), (s, 0.16H, PCHSi), (s, 0.84H, PCHSi). 13 C{ 1 H}NMR (100 MHz, C 6 D 6, 25 o C) for the major isomer: δ 167.3, (imine C), 147.7, 143.6, 142.9, (o-arc of DIPP), 141.3, (i-arc of DIPP), (d, 1 J P-C = 10.3 Hz, i-phc of PPh 2 ), (d, 2 J P-C = 15.0 Hz, o-phc of PPh 2 ), (d, 2 J P-C = 15.1 Hz, o-phc of PPh 2 ), 129.1, (p-phc of PPh 2 ), (d, 3 J P-C = 8.2 Hz, m-phc of PPh 2 ), (d, 3 J P-C = 8.6 Hz, m-phc of PPh 2 ), 127.0, 126.9, 124.8, 124.5, (m-arc of DIPP and p-arc of DIPP), 98.6 (MeC(N)CH), 68.0 (ScCH 2 ), 40.3 (d, 1 J P-C = 50.5 Hz, PCHSi), 39.1 (CH 2 CH(CH 3 )), 29.4, 28.9, 28.5 (CHMe 2 ), 25.6, 25.3, 25.0, 24.9, 24.2, 24.1, 24.0, 23.4, 22.9 (CHMe 2 and CMe), 3.9 (d, 3 J P-C = 2.3 Hz, SiMe 3 ). 31 P{ 1 H}NMR (202 MHz, C 6 D 6, 25 o C): δ (major), (minor). Anal. Calcd for C 45 H 60 N 2 PScSi: C 73.74; H 8.25; N Found: C 73.69; H 8.45; N : 2 (100 mg, 0.12 mmol) and pyridine (42 mg, 0.53 mmol) were mixed in 5 ml of toluene. After standing at room temperature for 0.5 h, the volatiles of the reaction solution were removed under vacuum, the residue was washed with 3 1 ml of hexane and dried under vacuum to give 4 as a yellow solid (89 mg, 88% yield). 1 H NMR (400 MHz, C 6 D 6, 25 o C): δ 8.66 (d, 3 J H-H = 5.1 Hz, 1H, Py-H), 8.19 (d, 3 J H-H = 7.3 Hz, 1H, Py-H), 7.54 (m, 4H, o-phh of PPh 2 ), 7.27 (t, 3 J H-H = 7.1 Hz, 1H, Py-H), 7.09 (m, 12H, m-phh of PPh 2, p-phh of PPh 2 and Ar-H), 6.79 (t, 3 J H-H = 6.0 Hz, 1H, Py-H), 5.26 (s, 1H, MeC(N)CH), 3.13 (sept, 3 J H-H = 6.5 Hz, 2H, CHMe 2 ), 2.89 (sept, S5

6 3 J H-H = 6.7 Hz, 2H, CHMe 2 ), 1.62 (s, 6H, CMe), 1.09 (d, 3 J H-H = 6.7 Hz, 6H, CHMe 2 ), 0.89 (m, 12H, CHMe 2 ), 0.80 (d, 3 J H-H = 6.7 Hz, 6H, CHMe 2 ), (s, 1H, PCHSi), (s, 9H, SiMe 3 ). 13 C{ 1 H}NMR (100 MHz, C 6 D 6, 25 o C): δ (ScC py ), (imine C), (i-arc of Dipp), (Py-C), 142.5, (o-arc of Dipp), (d, 1 J P-C = 3.5 Hz, i-phc of PPh 2 ), (d, 2 J P-C = 14.6 Hz, o-phc of PPh 2 ), (Py-C), (Py-C), (d, 4 J P-C = 1.1 Hz, p-phc of PPh 2 ), (d, 3 J P-C = 8.0 Hz, m-phc of PPh 2 ), (p-arc of DIPP), 124.6, 124.1(m-ArC of DIPP), (Py-C), 98.2 (MeC(N)CH), 37.8 (d, 1 J P-C = 55.4 Hz, PCHSi), 29.2, 28.7(CHMe 2 ), 25.2, 24.9, 23.6, 23.4 (CHMe 2 and CMe), 3.9 (d, 3 J P-C = 2.4 Hz, SiMe 3 ). 31 P{ 1 H}NMR (162 MHz, C 6 D 6, 25 o C): δ Anal. Calcd for C 50 H 65 N 3 PScSi: C 73.95; H 8.07; N Found: C 73.68; H 8.10; N : 2 (100 mg, 0.12 mmol) and 4-dimethylamino pyridine (15 mg, 0.12 mmol) were mixed in 5 ml of toluene. After standing at room temperature for 0.5 h, the volatiles of the reaction solution were removed under vacuum, and 1 ml of hexane was added to the residue. After standing at room temperature overnight, the solid was isolated, washed with 1 ml of cold hexane and dried under vacuum to afford 5 as a yellow crystalline solid (83 mg, 78% yield). 1 H NMR (400 MHz, C 6 D 6, 25 o C): δ 8.44 (d, 3 J H-H = 6.1 Hz, 1H, Py-H), 7.61 (t, 3 J H-H = 7.5 Hz, 4H, o-phh of PPh 2 ), 7.38 (d, 4 J H-H = 2.2 Hz, 1H, Py-H), (m, overlapped with the residual solvent resonance of the deuterated solvent, m-phh of PPh 2, p-phh of PPh 2 and Ar-H), 6.29 (dd, 3 J H-H = 6.2 Hz, 4 J H-H = 2.6 Hz, 1H, Py-H), 5.28 (s, 1H, MeC(N)CH), 3.20 (sept, 3 J H-H = 6.8 Hz, 4H, CHMe 2 ), 2.46 (s, 6H, NMe 2 ), 1.67 (s, 6H, CMe), 1.11 (d, 3 J H-H = 6.7 Hz, 6H, CHMe 2 ), 1.02 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 0.98 (m, 12H, CHMe 2 ), (s, 1H, PCHSi), (s, 9H, SiMe 3 ). 13 C{ 1 H}NMR (100 MHz, C 6 D 6, 25 o C): δ (ScC py ), (imine C), (Py-CNMe 2 ), (i-arc of Dipp), (o-arc of Dipp), (Py-C), (o-arc of Dipp), (i-phc of PPh 2 ), (d, 2 J P-C = 14.9 Hz, o-phc of PPh 2 ), (p-phc of PPh 2 ), (d, 3 J P-C = 7.8 Hz, m-phc of PPh 2 ), (p-arc of DIPP), 124.5, 124.1(m-ArC of DIPP), 110.5, (Py-C), 98.0 (MeC(N)CH), 38.7 (NMe 2 ), 36.2 (d, 1 J P-C = 56.0 Hz, PCHSi), 29.1, S6

7 28.7(CHMe 2 ), 25.6, 25.3, 25.0, 23.8, 23.7 (CHMe 2 and CMe), 4.1 (d, 3 J P-C = 2.5 Hz, SiMe 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6, 25 o C): δ Anal. Calcd for C 52 H 70 N 4 PScSi: C 73.03; H 8.25; N Found: C 73.05; H 8.42; N : 2 (100 mg, 0.12 mmol) and 1,3-dimethylpyrazole (26 mg, 0.27 mmol) were mixed in 5 ml of toluene. After standing at room temperature for 12 h, the volatiles of the reaction solution were removed under vacuum, and 1 ml of hexane was added to the residue. After standing at room temperature overnight, the solid was isolated, washed with 1 ml of cold hexane and dried under vacuum to afford 6 as a yellow crystalline solid (80 mg, 78% yield). 1 H NMR (400 MHz, C 6 D 6, 25 o C): δ 7.71 (t, 3 J H-H = 7.3 Hz, 4H, o-phh of PPh 2 ), 7.23 (d, 3 J H-H = 7.6 Hz, 2H, m-arh of DIPP), 7.16 (m, overlapped with the residual solvent resonance of the deuterated solvent, p-arh of DIPP), 7.03 (m, 6H, m-phh of PPh 2 and m-arh of DIPP), 6.90 (t, 3 J H-H = 7.3 Hz, 2H, p-phh of PPh 2 ), 6.32 (s, 1H, NCHCH), 5.34 (s, 1H, MeC(N)CH), 4.80 (s, 1H, NCHCH), 3.79 (br, 2H, CHMe 2 ), 2.96 (sept, 3 J H-H = 6.5 Hz, 2H, CHMe 2 ), 2.34 (s, 2H, ScCH 2 N), 1.68 (d, 3 J H-H = 5.9 Hz, 6H, CHMe 2 ), 1.53 (s, 6H, CMe), 1.47 (s, 3H, NCMe), 1.34 (d, 3 J H-H = 6.6 Hz, 6H, CHMe 2 ), 1.15 (s, 1H, PCHSi), 1.00 (d, 3 J H-H = 6.7 Hz, 6H, CHMe 2 ), 0.93 (br, 6H, CHMe 2 ), 0.10 (s, 9H, SiMe 3 ). 13 C{ 1 H}NMR (100 MHz, C 6 D 6, 25 o C): δ (imine C), (NC(CH)Me), (i-arc of Dipp), (d, 1 J P-C = 20.4 Hz, i-phc of PPh 2 ), 143.2, (o-arc of Dipp), (NCHCH), (d, 2 J P-C = 17.1 Hz, o-phc of PPh 2 ), (d, 3 J P-C = 7.1 Hz, m-phc of PPh 2 ), (p-phc of PPh 2 ) (p-arc of DIPP), 124.9, (m-arc of DIPP), (MeC(N)CH), (NCHCH), 53.0 (ScCH 2 N), 41.7 (d, 1 J P-C = 64.9 Hz, PCHSi), 29.3, 28.7 (CHMe 2 ), 26.7, 25.8, 25.3, 25.2, 23.8 (CHMe 2 and CMe), 12.4 (NC(CH)Me), 4.3 (d, 3 J P-C = 6.7 Hz, SiMe 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6, 25 o C): δ Anal. Calcd for C 50 H 68 N 4 PScSi: C 72.43; H 8.27; N Found: C 71.98; H 8.33; N : 2 (130 mg, 0.16 mmol) and 1-hexene (269 mg, 3.20 mmol) were mixed in 5 ml of toluene in a 25 ml tube with a Teflon stopcock. The tube was taken out of the S7

8 glovebox and connected to a Schlenk line. The solution was degassed and exposed to 1.0 atm of H 2 at room temperature. The tube was sealed and the reaction solution was allowed to warm to room temperature and stood at room temperature for 0.5 h. The volatiles of the solution were removed under vacuum, and 0.5 ml of cold hexane was added to the residue. After standing at -35 o C overnight, the solid was isolated, washed with 0.1 ml of cold hexane and dried under vacuum to afford 7 as a yellow crystalline solid (92 mg, 70% yield). 1 H NMR (400 MHz, C 6 D 6, 25 o C): δ (m, 6H, o-phh of PPh 2 and m-arh of DIPP), 7.15 (t, 3 J H-H = 7.5 Hz, 2H, p-arh of DIPP), (m, 6H, m-phh of PPh 2 and p-phh of PPh 2 ), 6.96 (dd, 3 J H-H = 7.5 Hz, 4 J H-H = 1.5 Hz, 2H, m-arh of DIPP), 5.17 (s, 1H, MeC(N)CH), 3.78 (sept, 3 J H-H = 6.9 Hz, 2H, CHMe 2 ), 2.77 (sept, 3 J H-H = 6.8 Hz, 2H, CHMe 2 ), 2.00 (m, 2H, CH 2 ), 1.61 (s, 6H, CMe), (m, 12H, CHMe 2 and CH 2 ), 1.37 (d, 3 J H-H = 6.7 Hz, 6H, CHMe 2 ), 1.03 (m, 5H, ScCH 2 and CH 3 ), 0.95 (d, 3 J H-H = 6.8 Hz, 6H, CHMe 2 ), 0.81 (d, 3 J H-H = 6.9 Hz, 6H, CHMe 2 ), (s, 9H, SiMe 3 ), (s, 1H, PCHSi). 13 C{ 1 H}NMR (100 MHz, C 6 D 6, 25 o C): δ (imine C), (i-phc of Dipp), 143.5, (o-arc of Dipp), (d, 1 J P-C = 5.7 Hz, i-phc of PPh 2 ), (d, 2 J P-C = 14.1 Hz, o-phc of PPh 2 ), (p-phc of PPh 2 ), (d, 3 J P-C = 8.2 Hz, m-phc of PPh 2 ), (p-arc of DIPP), 124.7, (m-arc of DIPP), 97.7 (MeC(N)CH), 59.9 (ScCH 2 ), 45.8 (d, 1 J P-C = 54.8 Hz, PCHSi), 37.2, 32.4, 30.3 (CH 2 ), 28.8 (CHMe 2 ), 26.4, 24.9, 24.8, 23.5 (CHMe 2, CMe and CH 2 ), 14.7 (CH 3 ), 3.7 (d, 3 J P-C = 2.1 Hz, SiMe 3 ). 31 P{ 1 H} NMR (162 MHz, C 6 D 6, 25 o C): δ Anal. Calcd for C 51 H 74 N 2 PScSi: C 74.78; H 9.11; N Found: C 74.93; H 9.17; N Reaction of 2 with Pyridine-d 5 : Pyridine-d 5 (2.6 mg, 31 µmol) in 0.5 ml of C 6 D 6 was added to 2 (10 mg, 12 µmol) at room temperature. The mixed reaction solution was immediately transferred into a NMR tube. After standing at room temperature for 0.5 h, the 1 H NMR spectrum was recorded. The volatiles of the reaction solution were removed under vacuum, and 0.5 ml of C 6 H 6 was added to the residue for the 2 H NMR spectrum. S8

9 Reaction of 2, D 2 and 1-hexene. D 2 (1.2 ml, 54 µmol) was injected into a sealed tube containing 2 (10 mg, 12 µmol), 1-hexene (21 mg, 250 µmol) and 0.5 ml of C 6 D 6. After standing at room temperature for 1.5 h, the volatiles of the reaction solution were removed under vacuum (for removing the excess of 1-hexene). 0.5 ml of C 6 D 6 was added to the residue, and the 1 H NMR spectrum was recorded. The C 6 D 6 was removed under vacuum, and 0.5 ml of C 6 H 6 was added to the residue for the 2 H NMR spectrum. X-ray Crystallography. Single crystals of 1 and 4 were grown from the toluene solutions, those of 2, 3, 5, 6 and 7 were grown from the toluene/hexane mixed solutions. The single crystals of 1-7 were mounted under nitrogen atmosphere on a glass fiber at low temperature, and data collection was performed on a Bruker APEX2 diffractometer with graphite-monochromated Mo Kα radiation (λ = Å). The SMART program package was used to determine the unit cell parameters. The absorption correction was applied using SADABS program. 4 All structures were solved by direct methods and refined on F 2 by full-matrix least-squares techniques with anisotropic thermal parameters for non-hydrogen atoms. Hydrogen atoms were placed at calculated positions and were included in the structure calculation. Calculations were carried out using the SHELXL-97, SHELXL-2014 or Olex2 program. 5 Crystallographic data and refinement for 4 7 are listed in Table S1. S9

10 Table S1 Crystallographic Data and Refinement for formula C 46 H 64 N 2 PScSi C 49 H 68 N 2 OPScSi C 45 H 60 N 2 PScSi fw color yellow orange yellow cryst syst. Monoclinic Triclinic Orthorhombic space group P P -1 P c a 21 a, Å (17) (17) (2) b, Å (3) (16) (17) c, Å (19) (4) (3) α, deg (3) 90 β, deg (3) (4) 90 γ, deg (2) 90 V, Å (6) (7) (10) Z D calcd, (mg/m 3 ) F(000) T(K) θ range, deg 1.758, , , no. of refns collected no. of unique refns no. of obsd refns (I > 2σ(I)) No. of params Final R, R w (I > 2σ(I)) , , , Goodness-of-fit on F ρ max, min, eå , , , S10

11 4 5 6 formula C 50 H 65 N 3 PScSi C 52 H 70 N 4 PScSi C 50 H 68 N 4 PScSi fw color yellow yellow yellow cryst syst. Monoclinic Orthorhombic Monoclinic space group P 1 21/c 1 P C 1 c 1 a, Å (11) (2) (10) b, Å (2) (4) (15) c, Å (2) (4) (16) α, deg β, deg (2) (2) γ, deg V, Å (8) (16) (7) Z D calcd, (mg/m 3 ) F(000) T(K) θ range, deg 1.903, , , no. of refns collected no. of unique refns no. of obsd refns (I > 2σ(I)) No. of params Final R, R w (I > 2σ(I)) , , , Goodness-of-fit on F ρ max, min, eå , , , S11

12 7 formula C 51 H 74 N 2 PScSi fw color cryst syst. yellow Monoclinic space group P 1 21/n 1 a, Å (11) b, Å (2) c, Å (17) α, deg 90 β, deg (2) γ, deg 90 V, Å (8) Z 4 D calcd, (mg/m 3 ) F(000) 1776 T(K) 130 θ range, deg 1.883, no. of refns collected no. of unique refns 7570 no. of obsd refns (I > 2σ(I)) No. of params 519 Final R, R w (I > 2σ(I)) , Goodness-of-fit on F ρ max, min, eå , S12

13 Figure S1. Molecular structure of complex 1 (ball-and-stick representation). DIPP isopropyl groups and hydrogen atoms (except H31) were omitted for clarity. Selected bond distances [Å] and angles [ ]: Sc N (4), Sc N (4), Sc C (5), Sc C (4), Sc P (15), C31 P 1.790(4), C31 Si 1.851(4), Sc C31 Si 139.6(2), Sc C31 P 79.47(17), Si C31 P 125.0(2). Figure S2. Molecular structure of complex 3 (ball-and-stick representation). DIPP isopropyl groups and hydrogen atoms (except H30) were omitted for clarity. Selected bond distances [Å] and angles [ ]: Sc N (5), Sc N (4), Sc C (5), Sc C (5), Sc P (19), Sc C30 Si 130.7(3), Sc C30 P 82.83(18), Si C30 P 129.6(3). S13

14 Figure S3. Molecular structure of complex 4 (ball-and-stick representation). DIPP isopropyl groups and hydrogen atoms (except H30) were omitted for clarity. Selected bond distances [Å] and angles [ ]: Sc N (14), Sc N (15), Sc N (15), Sc C (17), Sc C (19), Sc P (6), Sc C30 Si (9), Sc C30 P 78.16(7), Si C30 P (9). Figure S4. Molecular structure of complex 7 (ball-and-stick representation). DIPP isopropyl groups and hydrogen atoms (except H30) were omitted for clarity. Selected bond distances [Å] and angles [ ]: Sc N (19), Sc N (2), Sc C (2), Sc C (3), Sc P (8), Sc C30 Si (13), Sc C30 P 80.83(9), Si C30 P (13). S14

15 Figure S5. 1 H NMR spectrum of Li[CH(SiMe 3 )PPh 2 ](THF) (400 MHz, C 6 D 6, 25 o C). S15

16 Figure S6. 13 C{ 1 H} NMR spectrum of Li[CH(SiMe 3 )PPh 2 ](THF) (100 MHz, C 6 D 6, 25 o C). S16

17 Figure S7. 31 P{ 1 H} NMR spectrum of Li[CH(SiMe 3 )PPh 2 ](THF) (162 MHz, C 6 D 6, 25 o C). S17

18 Figure S8. 1 H NMR spectrum of 1(400 MHz, C 6 D 6, 25 o C). S18

19 Figure S9. 13 C{ 1 H} NMR spectrum of 1(100 MHz, C 6 D 6, 25 o C). S19

20 Figure S P{ 1 H} NMR spectrum of 1(162 MHz, C 6 D 6, 25 o C). S20

21 Figure S11. 1 H NMR spectrum of 2(400 MHz, THF-d 8, 25 o C). S21

22 Figure S C{ 1 H} NMR spectrum of 2(100 MHz, THF-d 8, 25 o C). S22

23 Figure S P{ 1 H} NMR spectrum of 2(162 MHz, THF-d 8, 25 o C). S23

24 Figure S14. 1 H NMR spectrum of 3(500 MHz, C 6 D 6, 25 o C). S24

25 Figure S C{ 1 H} NMR spectrum of 3(100 MHz, C 6 D 6, 25 o C). S25

26 Figure S P{ 1 H} NMR spectrum of 3(202 MHz, C 6 D 6, 25 o C). S26

27 Figure S17. 1 H NMR spectrum of 4(400 MHz, C 6 D 6, 25 o C). S27

28 Figure S C{ 1 H} NMR spectrum of 4(100 MHz, C 6 D 6, 25 o C). S28

29 Figure S P{ 1 H} NMR spectrum of 4(162 MHz, C 6 D 6, 25 o C). S29

30 Figure S20. 1 H NMR spectrum of 5(400 MHz, C 6 D 6, 25 o C). S30

31 Figure S C{ 1 H} NMR spectrum of 5(100 MHz, C 6 D 6, 25 o C). S31

32 Figure S P{ 1 H} NMR spectrum of 5(162 MHz, C 6 D 6, 25 o C). S32

33 Figure S23. 1 H NMR spectrum of 6(400 MHz, C 6 D 6, 25 o C). S33

34 Figure S C{ 1 H} NMR spectrum of 6(100 MHz, C 6 D 6, 25 o C). S34

35 Figure S P{ 1 H} NMR spectrum of 6(162 MHz, C 6 D 6, 25 o C). S35

36 Figure S26. 1 H NMR spectrum of 7(400 MHz, C 6 D 6, 25 o C). S36

37 Figure S C{ 1 H} NMR spectrum of 7(100 MHz, C 6 D 6, 25 o C). S37

38 Figure S P{ 1 H} NMR spectrum of 7(162 MHz, C 6 D 6, 25 o C). S38

39 Figure S29. 1 H NMR spectra showing the reversible process between 2 and 3. a) 2 mins after dissolution of 2 in C 6 D 6 ; b) 30 mins after dissolution of 2 in C 6 D 6 ; c) 1 h after dissolution of 2 in C 6 D 6. d) 20 mins after addition of 1 equiv of THF to the above reaction solution; e) 40 mins after the addition of 1 equiv of THF. S39

40 Figure S30. 1 H NMR spectrum of the reaction solution of 2 with pyridine-d 5 at 25 o C (400 MHz, C 6 D 6, 25 o C). S40

41 Figure S31. 2 H NMR spectrum of the product of the reaction solution of 2 with pyridine-d 5 at 25 o C (600 MHz, C 6 H 6, 25 o C). S41

42 Figure S32. 1 H NMR spectrum of the product of the reaction of 2, D 2 and 1-hexene at 25 o C (400 MHz, C 6 D 6, 25 o C). S42

43 Figure S33. 1 H- 1 H gcosy spectrum of the product of the reaction of 2, D 2 and 1-hexene at 25 o C (400 MHz, C 6 D 6, 25 o C). S43

44 Figure S34. 2 H NMR spectrum of the product of the reaction of 2, D 2 and 1-hexene at 25 o C (600 MHz, C 6 H 6, 25 o C). S44

45 Figure S35. 1 H 1 H NOESY spectrum of 3. S45

46 Figure S36. The conversion curves of 2 in C 6 D 6 at room temperature. S46

47 Computational details Calculations were carried out with Gaussian09 6 at the DFT level, with the hybrid functional B3PW91. 7 Scandium and silicon atoms were treated with small-core pseudopotentials from the Stuttgart group, with additional polarization orbitals. 8 The other atoms that were part of the systems (phosphorus, nitrogen, carbon, and hydrogen) were treated with the extended all electron Gaussian-Type 6-31G** Pople basis set. 9 No symmetry constraints were considered for the geometry optimizations that took as starting point the experimentally obtained geometries of both reagents and products. Analytical calculations of the vibrational frequencies confirmed that the structures obtained were the critical points involved in the reactive process, and also obtained the thermal corrections over the energies. Transition states obtained where connected with its respective intermediates with Intrinsic Reaction Coordinate (IRC) calculations. Bonding was studied doing Natural Bond Orbital analysis over the optimized structures, with NBO software. 10 S47

48 Cartesian coordinates of all optimized structures 123 Scandium phosphino-alkylidene Sc P Si O N N C C C C C C C C C C C C C C C C C C C C C S48

49 C C C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H S49

50 H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H S50

51 H H H H H H H H Pyrazole s addition intermediate 1 Sc P Si N N N N C C C C C C C C C C C C C C C C C C C S51

52 C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H S52

53 H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H S53

54 H H H H H H H H H H H Pirazole s addition intermediate 2 Sc P Si N N N N C C C C C C C C C C C C C C C C S54

55 C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H H H H S55

56 H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H S56

57 H H H H H H H H H H H H H H Pyrazole s addition transition state Sc P Si N N N N C C C C C C C C C C C C C S57

58 C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H S58

59 H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H S59

60 H H H H H H H H H H H H H H H H H Pyrazole s addition final product Sc P Si N N N N C C C C C C C C C C C S60

61 C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H S61

62 H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H S62

63 H H H H H H H H H H H H H H H H H H H Pyrazole s addition intermedate 2 (isomer) Sc P Si N N N N C C C C C C C C C C C C C C C S63

64 C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H H H S64

65 H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H S65

66 H H H H H H H H H H H H H H H Pyrazole s addition transition state (isomer) Sc P Si N N N N C C C C C C C C C C C C C C C C C C C S66