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

Supporting information

Lewis acid–base synergistic catalysis of cationic halogen-bonding-donors with nucleophilic counter anions

Koki Torita,a Ryosuke Haraguchi,*b Yoshitsugu Morita,a Satoshi Kemmochi,a Teruyuki Komatsu,a and Shin-ichi Fukuzawa*a

aDepartment of Applied Chemistry, Institute of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, 112-8551 Tokyo, Japan bDepartment of Applied Chemistry, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan.

Contents

Instrumentation and Chemicals S2

Effect of Counter Anions on the Catalytic Activity S4

Effect of Water on the Catalytic Efficiency S4

NMR Titration Experiment S5

Experimental Procedure S7

Characterization Data S11

Theoretical Study S18

NMR Spectra Data S38

References S77

S1 Instrumentation and Chemicals All manipulations of oxygen- and moisture-sensitive materials were conducted under argon or nitrogen atmosphere in a flame dried Schlenk flask. Nuclear magnetic resonance spectra were taken on a JEOL ECA spectrometer using tetramethylsilane for 1 H NMR as an internal standard (δ = 0 ppm) when CDCl3 was used as a solvent, using 1 CD3CN for H NMR as an internal standard (δ = 1.94 ppm) when CD3CN was used as a 1 solvent, using (CD3)2SO for H NMR as an internal standard (δ = 2.50 ppm) when 13 (CD3)2SO was used as a solvent, using CDCl3 for C NMR as an internal standard (δ = 13 77.16 ppm) when CDCl3 was used as a solvent, using CD3CN for C NMR as an internal standard (δ = 118.26 ppm) when CD3CN was used as a solvent, using (CD3)2SO 13 for C NMR as an internal standard (δ = 39.52 ppm) when (CD3)2SO was used as a solvent. 1H NMR, 13C NMR, and 19F NMR data are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, quint = quintet, sext = sextet, sept = septet, br = broad, m = multiplet), coupling constants (Hz), and integration. High-resolution mass spectra (HRMS) were measured by a JEOL JMS-T100LC AccuTOF. Infrared (IR) spectra were measured by an FT/IR-4100ST spectrometer. Potassium hexafluorophosphate was purchased from Tokyo Chemical Industry Co., Ltd. (P1023, >95%). tert-Butyl hypochlorite was purchased from Tokyo Chemical Industry Co., Ltd. (H0362, >98%). Potassium tert-butoxide was purchased from Tokyo Chemical Industry Co., Ltd. (P1008, >97%). Ethynylbenzene was purchased from Tokyo Chemical Industry Co., Ltd. (E0196, >98%). 4-Chlorobenzaldehyde was purchased from Tokyo Chemical Industry Co., Ltd. (C0125, >97%). 4-Acetylbenzaldehyde was purchased from Sigma-Aldrich Co. LLC (516333, 97%). Trimethylsilyl cyanide was purchased from Tokyo Chemical Industry Co., Ltd. (T0990, >96%). Iodine was purchased from nacalai tesque (19220-95, >99.8%). 4-Methoxybenzaldehyde was purchased from Tokyo Chemical Industry Co., Ltd. (A0480, >99%). N-(4-Methoxybenzylidene)aniline was purchased from Tokyo Chemical Industry Co., Ltd. (M0582, >98%). Styrene oxide was purchased from Tokyo Chemical Industry Co., Ltd. (E0013, >98%). Carbon dioxide was purchased from TOMOE SHOKAI Co.,LTD. (3407-a, >99.9%). Tetrahydrofuran was purchased from Kanto Chemical Co., Inc. (40993-95, >99.5%). Dichloromethane was purchased from Kanto Chemical Co., Inc. (10158-81, >99%), distilled from calcium hydride and stored under nitrogen. Unless otherwise noted, commercially available reagents were used without purification. 1,3-Bis(2,6-diisopropylphenyl)triazene[1], 1,3-bis(2,4,6-trimethylphenyl)triazene[1], 1,3-diphenyltriazene[2], 1-ethynyl-4-trifluoromethylbenzene[3], 4-ethynyltoluene[3],

S2 4-ethynylanisole[3], 2-ethynyl-1,3-diisopropylbenzene[3], 1-ethynyl-2,4,6-trimethylbenzene[3], were prepared according to the literature.

S3 Effect of Counter Anions on the Catalytic Activity

(a) iodide vs tetrafluoroborate

O OTMS catalyst (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a

CF3 CF3 with 5aa-I: 99%

with 5aa-BF4: 49%

i-Pr i-Pr

N N i-Pr I I i-Pr I BF4 N N N N i-Pr i-Pr i-Pr i-Pr

5aa-I 5aa-BF4 (b) iodide vs hexafluorophosphate

O OTMS catalyst (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a

with 5af-I: 47%

with 5af-PF6: 26%

i-Pr i-Pr

N N i-Pr I I i-Pr I PF6 N N N N i-Pr i-Pr i-Pr i-Pr

5af-I 5af-PF6 Scheme. S1 Investigation of the effect of counter anions of cationic XB-donors 5 on the catalytic activity for the cyanosilylation of aldehyde 6a.

Effect of Water on the Catalytic Efficiency

O H2O (1.5 eq) OTMS 5aa-I (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a trace

Scheme. S2 Investigation of the effect of water on the catalytic activity for the cyanosilylation of aldehyde 6a.

S4 NMR Titration Experiment

13 13 Fig. S1 (a) C NMR spectra of 5aa-I with 10 equivalents of 6a in CDCl3. (b) C NMR spectra of 1 1 5aa-I in CDCl3. (c) H NMR spectra of TMSCN with 1 equivalent of 5aa-I in CDCl3. (d) H NMR spectra of TMSCN in CDCl3.

S5

1 1 Fig. S2 (a) H NMR spectra of TMSCN with 1 equivalent of (n-Bu)4I in CDCl3. (b) H NMR spectra of TMSCN in CDCl3.

S6 Experimental Procedure General procedure for preparation of 1,3,4-triaryl-1H-1,2,3-triazolium salts 3

2 KPF6 (2.3 eq) Ar t-BuOCl (2.3 eq) Ar1 1 N 1 N Ar Ar + H N N 2 N H Ar CH2Cl2, –78 °C N to rt, 17 h PF6 1 1 (1.5 eq) 2 Ar 3

Following the reported procedure,[4] the reaction was performed in a 50-mL Schlenk flask equipped with a magnetic stirring bar and a septum. To a solution of triazene 1 (3.0 mmol) and potassium hexafluorophosphate (4.6 mmol, 0.85 g) in dichloromethane (10 mL) was added tert-butyl hypochlorite (4.6 mmol, 0.50 g) at −78 °C, and the resulting mixture was stirred at the same temperature for 30 min. Then, alkyne 2 (2.0 mmol) was added to the reaction mixture at −78 °C. The mixture was allowed to warm to room temperature and stirred for the additional 17 h. The resulting mixture was filtered through a pad of Celite, and the pad was rinsed with dichloromethane. The filtrate was concentrated in vacuo. Diethyl ether was added to the residue, the precipitate was filtered to give 1,3,4-triarylated-1H-1,2,3-triazolium salts 3.

General procedure for preparation of 1,3,4-triaryl-1H-5-iodo-1,2,3-triazolium salts 5

Ar2 1) t-BuOK (1.5 eq) Ar2 Ar1 THF, 0 °C, 3 h Ar1 N N H I I N N 2) I2 (3.0 eq), 30 °C, 17 h N N PF6 Ar1 Ar1 3 5

The reaction was performed in a 50-mL Schlenk flask equipped with a magnetic stirring bar and a septum. 1,3,4-triaryl-1H-1,2,3-triazolium salts 3 (1.0 mmol) was dissolved in THF (10 mL) under a nitrogen atmosphere, and the mixture was cooled to 0 °C. To a stirred solution potassium was added tert-butoxide (1.5 mmol, 0.17 g), and the mixture was stirred at 0 °C for 3 h. To the reaction mixture was added iodine (3.0 mmol, 0.76 g) at 0 °C, and the mixture was allowed to warm to 30 °C. After being stirred for 17 h, the mixture was poured into a saturated aqueous solution sodium thiosulfate. The resulting mixture was extracted with dichloromethane. The combined organic layers were washed

S7 with water and brine, dried over sodium sulfate, and concentrated in vacuo. To the residue was added the mixture of Et2O/acetone (5/1), and the precipitate was filtered to give the corresponding 1,3,4-triaryl-1H-5-iodo-1,2,3-triazolium salts 5.

Procedure for preparation of 5aa-BF4

CF3 CF3

i-Pr i-Pr

N AgBF4 (1.5 eq) N i-Pr I I i-Pr I BF N N 4 N CH2Cl2, rt, 18 h N i-Pr i-Pr i-Pr i-Pr

5aa-I 5aa-BF4 79% yield

The reaction was performed in a 50-mL Schlenk flask equipped with a magnetic stirring bar and a septum. Silver tetrafluoroborate (1.1 mmol) and iodotriazolium iodide 5aa-I (0.7 mmol) were dissolved in dichloromethane (10 mL) under a nitrogen atmosphere. After the mixture was stirred at room temperature for 18 h in the dark, the mixture was filtered through a pad of Celite. The filtrate was concentrated in vacuo to give 5aa-BF4 in 79% yield.

S8 General procedure for the reaction of 6a with trimethyl silylcyanide

O OTMS catalyst (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a

To a 1-mL vial were added sequentially 6a (0.20 mmol, 28 mg), TMSCN (0.30 mmol, 30 mg), catalyst (0.0010 mmol), and dichloromethane (0.20 mL). After the vial was purged with argon and capped, the reaction mixture was stirred at 30 °C for 1 h. And then, the mixture was passed through a short silica gel pad. The filtrate was concentrated under reduced pressure, affording an yellowish oil. Yields were calculated based on the 1H NMR analysis of the crude reaction mixture using dibromomethane as the internal standard.

Procedure for the reaction of 6c with trimethyl silylcyanide

O TMSCN (1.5 eq) OTMS OTMS catalyst (0.5 mol %) H CN + CN CH2Cl2, 30 °C, 1 h NC

O 6c O OTMS 7c 8c

To a 1-mL vial were added sequentially 6c (0.20 mmol, 30 mg), TMSCN (0.30 mmol, 30 mg), catalyst (0.0010 mmol), and dichloromethane (0.20 mL) After the vial was purged with argon and capped, the reaction mixture was stirred at 30 °C for 1 h. And then, the mixture was passed through a short silica gel pad. The filtrate was concentrated under reduced pressure, affording an yellowish oil. Yields were calculated based on the 1H NMR analysis of the crude reaction mixture using dibromomethane as the internal standard.

S9

Procedure for the reaction of 6c with trimethylsilylcyanide

O

H OTMS MeO TMSCN (1.0 eq) NHPh catalyst (0.5 mol %) 6d CN CN + CH2Cl2, 30 °C, 1 h NPh MeO MeO 7d 10 H

MeO 9 (1.0 eq)

To a 1-mL vial were added sequentially 6d (0.20 mmol, 27 mg), 9 (0.20 mmol, 42 mg), TMSCN (0.20 mmol, 20 mg), catalyst (0.0010 mmol), and dichloromethane (0.20 mL) After the vial was purged with argon and capped, the reaction mixture was stirred at 30 °C for 1 h. And then, the mixture was passed through a short silica gel pad. The filtrate was concentrated under reduced pressure, affording an yellowish oil. Yields were calculated based on the 1H NMR analysis of the crude reaction mixture using dibromomethane as the internal standard

Procedure for the reaction of 11 with carbon dioxide

O catalyst (15 mol %) O O O + CO2 PhCl, 120 °C, 24 h Ph Ph 11 12

To a schlenk flask were added 11 (0.20 mmol, 27 mg) and catalyst (0.030 mmol). The flask was quickly evacuated and filled with carbon dioxide (1 atm, balloon). After repeating this operation three times, chlorobenzene (1.0 mL) was added to the mixture. The reaction mixture was stirred at 120 °C for 24 h. And then, the mixture was cooled to room temperature and passed through a short silica gel pad. The filtrate was concentrated under reduced pressure, affording an yellowish oil. Yields were calculated based on the 1H NMR analysis of the crude reaction mixture using dibromomethane as the internal standard

S10 Characterization Data

1,3-Bis-(2,6-diisopropylphenyl)-4-(4-trifluoromethylphenyl)-1H-1,2,3-triazolium hexafluorophosphate (3aa-PF6) 1 CF3 Yield: 84% (5.19 g); white solid; H NMR (400 MHz, (CD3)2SO) δ: 10.35 (s, 1H), 8.04 (d, J = 8.3 Hz, 2H), 7.80 (t, J = 7.8 Hz, 2H), 7.68 i-Pr (d, J = 8.3 Hz, 2H), 7.63 (d, J = 7.8 Hz, 2H), 7.62 (d, J = 7.8 Hz, 2H), N i-Pr H PF6 N N 2.52 (seq, J = 6.8 Hz, 2H), 2.42 (seq, J = 6.7 Hz, 2H), 1.30 (d, J = 6.7 i-Pr i-Pr Hz, 6H), 1.13 (d, J = 6.8 Hz, 6H), 1.09 (d, J = 6.8 Hz, 6H), 0.99 (d, J 13 = 6.7 Hz, 6H) ppm; C NMR (100 MHz, (CD3)2SO) δ: 145.1, 145.0, 3aa-PF6 143.7, 134.3, 133.9, 133.4, 131.9 (q, J = 33 Hz), 130.3, 129.7, 128.6, 126.5 (q, J = 3.7 Hz), 126.0 (q, J = 1.3 Hz), 125.9, 125.1, 123.5 (q, J = 273 Hz), 28.6, + 28.4, 24.9, 24.5, 23.5, 22.2 ppm; ESI-HRMS (m/z): [M–I] calcd for C33H39F3N3 534.3091, found 534.3120.

1,3-Bis-(2,6-diisopropylphenyl)-4-(4-methylphenyl)-1H-1,2,3-triazolium hexafluorophosphate (3ab-PF6) Me 1 Yield: 61% (3.07 g); white solid; H NMR (400 MHz, CD3CN) δ: 9.16 (s, 1H), 7.76 (t, J = 7.9 Hz, 2H), 7.56 (d, J = 7.9 Hz, 2H), 7.53 i-Pr

N (d, J = 7.8 Hz, 2H), 7.35–7.26 (m, 4H), 2.45 (seq, J = 6.8 Hz, 2H), i-Pr H PF6 N N 2.37 (seq, J = 6.8 Hz, 2H), 2.36 (s, 3H), 1.31 (d, J = 6.8 Hz, 6H), i-Pr i-Pr 1.18 (d, J = 6.8 Hz, 6H), 1.12 (d, J = 6.8 Hz, 6H), 1.02 (d, J = 6.8 Hz, 13 3ab-PF6 6H) ppm; C NMR (100 MHz, CD3CN) δ: 146.8, 146.5, 146.4, 144.6, 134.6, 134.4, 132.4, 131.4, 131.1, 130.4, 129.5, 126.6, 126.1, 119.8, 30.1, 29.8, 25.4, 24.9, 23.9, 22.6, 21.5 ppm; IR (KBr): 3434, 3147, 2932, 2875, 1613, 1538, 1557, 1506, 1449, 1390, 1369, 1331, 1281, 1223, 1188, 1062, 994, 937, 954, 508, 445 cm–1; + ESI-HRMS (m/z): [M–I] calcd for C33H42N3 480.3373, found 480.3362.

1,3-Bis-(2,6-diisopropylphenyl)-4-(4-methoxyphenyl)-1H-1,2,3-triazolium hexafluorophosphate (3ac-PF6) OMe 1 Yield: 82% (2.75 g); yellowish solid; H NMR (400 MHz, CD3CN) δ: 9.08 (s, 1H), 7.77 (t, J = 7.8 Hz, 1H), 7.76 (t, J = 7.8 Hz, 1H), 7.55 (d, i-Pr

N J = 7.8 Hz, 2H), 7.54 (d, J = 7.8 Hz, 2H), 7.34 (d, J = 8.9 Hz, 2H), i-Pr H PF6 N N 7.02 (d, J = 8.9 Hz, 2H), 3.81 (s, 3H), 2.46 (seq, J = 6.8 Hz, 2H), 2.38 i-Pr i-Pr (seq, J = 6.8 Hz, 2H), 1.31 (d, J = 6.8 Hz, 6H), 1.17 (d, J = 6.8 Hz, 13 3ac-PF6 6H), 1.12 (d, J = 6.8 Hz, 6H), 1.04 (d, J = 6.8 Hz, 6H) ppm; C NMR

S11 (100 MHz, CDCl3) δ:163.7, 146.6, 146.5, 146.4, 134.6, 134.3, 131.8, 131.4, 131.4, 130.4, 136.7, 126.0, 116.0, 114.6, 56.4, 30.1, 29.8, 25.3, 24.9, 23.9, 22.7 ppm; IR (KBr): 3587, 3421, 3147, 3079, 2971, 2930, 2875, 2574, 1984, 1913, 1608, 1582, 1503, 1460, 1390, 1369, 1322, 1302, 1275, 1223, 1186, 1062, 1027, 993, 937, 754, 650, 601, –1 + 562, 522, 448 cm ; ESI-HRMS (m/z): [M–I] calcd for C33H42N3O 496.3322, found 496.3334.

1,3,4-Tris-(2,6-diisopropylphenyl)-1H-1,2,3-triazolium hexafluorophosphate

(3ad-PF6, CAS Registry Number 1294447-84-9) Yield: 47% (655 mg); yellowish solid; 1H NMR (400 MHz, i-Pr i-Pr i-Pr (CD3)2SO) δ: 10.20 (s, 1H), 7.85 (t, J = 7.8 Hz, 1H), 7.73 (t, J = 7.8 N i-Pr H PF6 Hz, 1H), 7.69 (d, J = 7.8 Hz, 2H), 7.65 (t, J = 7.8 Hz, 1H), 7.58 (d, J N N i-Pr i-Pr = 7.8 Hz, 2H), 7.47 (d, J = 7.8 Hz, 2H), 2.35 (seq, J = 6.8 Hz, 2H), 2.24 (seq, J = 6.8 Hz, 2H), 2.16 (seq, J = 6.6 Hz, 2H), 1.31 (d, J = 3ad-PF 6 6.7 Hz, 6H), 1.26 (d, J = 6.8 Hz, 6H), 1.15 (d, J = 6.7 Hz, 6H), 1.08 (d, J = 6.7 Hz, 6H), 0.99 (d, J = 6.6 Hz, 6H), 0.94 (d, J = 6.6 Hz, 6H) ppm; 13C NMR

(100 MHz, (CD3)2SO) δ: 148.4, 144.7, 144.3, 142.7, 136.3, 136.3, 133.6, 133.3, 129.9, 129.2, 126.1, 125.3, 124.9, 117.4, 31.5, 29.7, 29.3, 25.8, 25.7, 23.6, 23.3, 21.8, 21.1 ppm.

1,3-Bis-(2,6-diisopropylphenyl)-4-(2,4,6-trimethylphenyl)-1H-1,2,3-triazolium hexafluorophosphate (3ae-PF6, CAS Registry Number 1294447-81-5) 1 Me Yield: 48% (1.63 g); yellowish solid; H NMR (400 MHz,

Me CD3CN) δ: 9.10 (s, 1H), 7.78 (t, J = 7.9 Hz, 1H), 7.67 (t, J = 7.9 Hz, i-Pr Me 1H), 7.58 (d, J = 7.9 Hz, 2H), 7.44 (d, J = 7.9 Hz, 2H), 7.05 (s, 2H), N i-Pr H PF6 N N 2.40–2.24 (m, 4H), 2.27 (s, 3H), 2.14 (s, 6H), 1.32 (d, J = 6.9 Hz, i-Pr i-Pr 6H), 1.25 (d, J = 6.9 Hz, 6H), 1.10 (d, J = 6.8 Hz, 6H), 1.02 (d, J = 13 3ae-PF6 6.8 Hz, 6H) ppm; C NMR (100 MHz, CD3CN) δ: 146.3, 146.2, 145.8, 143.8, 139.4, 135.8, 134.5, 134.5, 131.2, 130.7, 130.5, 126.5, 126.1, 118.5, 30.7, 30.3, 26.5, 24.3, 24.1, 21.6, 21.3, 21.2 ppm.

S12 1,3-Bis-(2,6-diisopropylphenyl)-4-phenyl-1H-1,2,3-triazolium hexafluorophosphate

(3af-PF6, CAS Registry Number 1294447-78-1) Yield: 62% (2.07 g); yellowish solid; 1H NMR (400 MHz, i-Pr CD3CN) δ: 9.17 (s, 1H), 7.79–7.73 (m, 2H), 7.63–7.48 (m, 7H), N i-Pr H PF6 7.44–7.39 (m, 2H), 2.46 (seq, J = 6.8 Hz, 2H), 2.38 (seq, J = 6.8 Hz, N N i-Pr i-Pr 2H), 1.31 (d, J = 6.8 Hz, 6H), 1.18 (d, J = 6.8 Hz, 6H), 1.13 (d, J = 6.8 Hz, 6H), 1.01 (d, J = 6.8 Hz, 6H) ppm; 13C NMR (100 MHz, 3af-PF6 CD3CN) δ: 146.7, 146.4, 146.4, 134.6, 134.4, 133.5, 132.7, 131.4, 130.5, 130.2, 129.7, 126.7, 126.1, 122.7, 30.1, 29.9, 25.5, 24.9, 23.9, 22.6 ppm.

4-Phenyl-1,3-bis-(2,4,6-trimethylphenyl)-1H-1,2,3-triazolium hexafluorophosphate

(3bf-PF6, CAS Registry Number 1294448-13-7) Yield: 91% (1.85 g); yellowish solid; 1H NMR (400 MHz, Me Me (CD3)2SO) δ: 10.03 (s, 1H), 7.61 (tt, J = 7.3, 1.5 Hz, 1H), N Me H PF6 7.58–7.52 (m, 2H), 7.51–7.46 (m, 2H), 7.29 (s, 2H), 7.25 (s, 2H), N N 13 Me 2.40 (s, 3H), 2.37 (s, 3H), 2.22 (s, 6H), 2.04 (s, 6H) ppm; C Me NMR (100 MHz, (CD3)2SO) δ: 144.1, 142.8, 142.5, 134.6, 134.3, Me 132.8, 132.7, 132.3, 131.2, 130.2, 129.8, 129.7, 129.7, 128.3, 3bf-PF6 122.1, 20.8, 20.8, 16.9, 16.9 ppm.

1,3,4-Triphenyl-1H-1,2,3-triazolium hexafluorophosphate (3cf-PF6 CAS Registry Number 1294448-17-1) Yield: 32% (429 mg); purple solid; 1H NMR (400 MHz,

(CD3)2SO) δ: 10.08 (s, 1H), 8.20–8.13 (m, 2H), 7.88–7.78 (m, 3H), N H PF6 13 N N 7.78–7.65 (m, 5H), 7.64–7.52 (m, 3H), 7.50–7.43 (m, 2H) ppm; C NMR (100 MHz, (CD3)2SO) δ: 143.4, 134.8, 134.0, 132.3, 132.3, 131.7, 130.7, 130.3, 129.4, 129.3, 127.7, 126.3, 122.5, 121.7 ppm. 3 f-PF c 6 1,3-Bis-(2,6-diisopropylphenyl)-5-iodo-4-(4-trifluoromethylphenyl)-1H-1,2,3-triazo lium iodide (5aa-I)

CF3 1 Yield: 59% (93 mg); yellowish solid; H NMR (400 MHz, CDCl3) δ: 7.72–7.58 (m, 6H), 7.42 (d, J = 7.8 Hz, 2H), 7.33 (d, J = 7.9 Hz, 2H), i-Pr

N 2.29–2.16 (m, 4H), 1.39 (d, J = 6.8 Hz, 6H), 1.16 (d, J = 6.8 Hz, 6H), i-Pr I I N N 13 i-Pr 1.13 (d, J = 6.9 Hz, 6H), 1.03 (d, J = 6.8 Hz, 6H) ppm; C NMR (100 i-Pr MHz, CDCl3) δ: 145.7, 145.2, 145.2, 133.6 (q, J = 34 Hz), 133.6,

5aa-I 133.4, 131.3, 130.5, 129.1, 126.4 (q, J = 3.7 Hz), 126.2 (q, J = 1.3

S13 Hz), 125.4, 125.2, 123.2 (q, J = 273 Hz), 111.7, 29.8, 29.6, 25.8, 25.1, 23.6, 22.6 ppm; IR (KBr): 3448, 2968, 2932, 2871, 1622, 1467, 1389, 1366, 1325, 1200, 1173, 1134, 1082, 1065, 1020, 992, 844, 805, 754, 558 cm–1; ESI-HRMS (m/z): [M–I]+ calcd for

C33H38F3IN3 660.2057, found 660.2093.

1,3-Bis-(2,6-diisopropylphenyl)-5-iodo-4-(4-methylphenyl)-1H-1,2,3-triazolium iodide (5ab-I) 1 Me Yield: 89% (271 mg); white solid; H NMR (400 MHz, CDCl3) δ: 7.67 (t, J = 7.8 Hz, 1H), 7.60 (t, J = 7.8 Hz, 1H), 7.42 (d, J = 7.8 Hz, i-Pr 2H), 7.32 (d, J = 7.8 Hz, 2H), 7.29 (d, J = 8.3 Hz, 2H), 7.21 (d, J = N i-Pr I I N N 8.3 Hz, 2H), 2.36 (s, 3H), 2.27–2.14 (m, 4H), 1.40 (d, J = 6.7 Hz, i-Pr i-Pr 6H), 1.16 (d, J = 6.9 Hz, 6H), 1.14 (d, J = 6.9 Hz, 6H), 1.03 (d, J = 13 5ab-I 6.7 Hz, 6H) ppm; C NMR (100 MHz, CDCl3) δ: 147.3, 145.2, 145.1, 142.8, 133.3, 133.2, 131.4, 130.2, 129.6, 129.6, 125.2, 125.2, 119.4, 109.6, 29.8, 29.6, 25.7, 25.1, 23.6, 22.6, 21.6 ppm; IR (KBr): 3432, 2967, 2931, 2871, 1613, 1468, 1389, 1367, 1327, 1233, 1201, 1060, 995, 937, 755, 557 cm–1; + ESI-HRMS (m/z): [M–I] calcd for C33H41IN3 606.2340, found 606.2325.

1,3-Bis-(2,6-diisopropylphenyl)-5-iodo-4-(4-methoxyphenyl)-1H-1,2,3-triazolium iodide (5ac-I) 1 OMe Yield: 70% (212 mg); white solid; H NMR (400 MHz, CDCl3) δ: 7.66 (t, J = 7.9 Hz, 1H), 7.61 (t, J = 7.9 H, 1H), 7.41 (d, J = 7.9 Hz, i-Pr 2H), 7.34 (d, J = 8.9 Hz, 2H), 7.32 (d, J = 7.9 Hz, 2H), 6.88 (d, J = N i-Pr I I N N 8.9 Hz, 2H), 3.81 (s, 3H), 2.26–2.13 (m, 4H), 1.39 (d, J = 6.8 Hz, i-Pr i-Pr 6H), 1.15 (d, J = 6.9 Hz, 6H), 1.13 (d, J = 6.9 Hz, 6H), 1.03 (d, J = 13 6.8 Hz, 6H) ppm; C NMR (100 MHz, CDCl3) δ: 162.2, 147.1, 5ac-I 145.2, 145.1, 133.2, 131.4, 131.3, 129.6, 125.2, 125.1, 115.0, 114.1, 108.4, 55.7, 29.7, 29.6, 25.6, 25.1, 23.5, 22.6 ppm; IR (KBr): 3467, 2968, 2932, 2871, 1608, 1488, 1466, 1389, 1301, 1262, 1179, 1060, 1026, 843, 805, 755, 557cm–1; + ESI-HRMS (m/z): [M–I] calcd for C33H41IN3O 622.2289, found 622.2286.

S14 1,3,4-Tris-(2,6-diisopropylphenyl)-5-iodo-1H-1,2,3-triazolium iodide (5ad-I) Yield: 66% (212 mg); yellowish solid; 1H NMR (400 MHz, i-Pr i-Pr i-Pr CDCl3) δ: 7.70 (t, J = 7.9 Hz, 1H), 7.57 (t, J = 7.8 Hz, 1H), 7.52 (t, J N i-Pr I I = 7.9 Hz, 1H), 7.43 (d, J = 7.9 Hz, 2H), 7.31 (d, J = 7.8 Hz, 2H), N N i-Pr 7.25 (d, J = 7.9 Hz, 2H), 2.35 (seq, J = 6.8 Hz, 2H), 2.18−2.06 (m, i-Pr 4H), 1.37 (d, J = 6.8 Hz, 6H), 1.28−1.16 (m, 12H), 1.08 (d, J = 6.8 5ad-I Hz, 6H) 0.92 (d, J = 6.7 Hz, 6H), 0.91 (d, J = 6.6 Hz, 6H), ppm; 13C

NMR (100 MHz, CDCl3) δ: 149.1, 148.1, 145.4, 144.9, 133.6, 133.2, 133.1, 130.8, 130.2, 125.7, 125.5, 125.3, 119.0, 110.6, 31.8, 30.2, 30.1, 27.2, 26.8, 24.9, 23.7, 22.6, 21.4 ppm; IR (KBr): 3442, 3130, 3086, 2969, 2933, 2874, 1596, 1550, 1468, 1391, 1369, 1328, 1211, 1184, 1061, 988, 936, 846, 755, 558 cm–1; ESI-HRMS (m/z): [M−I]+ calcd for C38H51IN3 676.3122, found 676.3109.

1,3-Bis-(2,6-diisopropylphenyl)-5-iodo-4-(2,4,6-trimethylphenyl)-1H-1,2,3-triazoliu m iodide (5ae-I) Me 1 Yield: 72% (219 mg); white solid; H NMR (400 MHz, CDCl3) δ: Me 7.68 (t, J = 7.8 Hz, 1H), 7.54 (t, J = 7.8 Hz, 1H), 7.42 (d, J = 7.8 Hz, i-Pr Me N 2H), 7.28 (d, J = 7.8 Hz, 2H), 6.90 (s, 2H), 2.31 (seq, J = 6.8 Hz, i-Pr I I N N i-Pr 2H), 2.27 (s, 3H), 2.20 (seq, J = 6.9 Hz, 2H), 2.11 (s, 6H), 1.40 (d, J i-Pr = 6.8 Hz, 6H), 1.20 (d, J = 6.9 Hz, 6H), 1.09 (d, J = 6.9 Hz, 6H), 13 5ae-I 1.07 (d, J = 6.8 Hz, 6H) ppm; C NMR (100 MHz, CDCl3) δ: 148.8, 145.2, 145.2, 142.3, 138.1, 133.3, 133.1, 131.2, 130.0, 129.8, 125.2, 125.2, 118.2, 113.4, 29.8, 29.7, 26.9, 24.7, 23.7, 21.6, 21.2, 20.8 ppm; IR (KBr): 3447, 2968, 2931, 2872, 1613, 1467, 1389, 1367, 1351, 1323, 1298, 1200, 1060, 994, 986, 809, 755, 558 cm–1; + ESI-HRMS (m/z): [M–I] calcd for C35H45IN3 634.2653, found 634.2667.

1,3-Bis-(2,6-diisopropylphenyl)-5-iodo-4-phenyl-1H-1,2,3-triazolium iodide (5af-I) 1 Yield: 78% (226 mg); white solid; H NMR (400 MHz, CDCl3) δ: i-Pr 7.68 (t, J = 7.9 Hz, 1H), 7.61 (t, J = 7.9 Hz, 1H), 7.53–7.38 (m, 7H), N i-Pr I I 7.32 (d, J = 7.9 Hz, 2H), 2.28–2.14 (m, 4H), 1.40 (d, J = 6.8 Hz, N N i-Pr 6H), 1.17 (d, J = 6.9 Hz, 6H), 1.14 (d, J = 6.9 Hz, 6H), 1.02 (d, J = i-Pr 13 6.8 Hz, 6H) ppm; C NMR (100 MHz, CDCl3) δ: 147.0, 145.2, 5af-I 145.1, 133.4, 133.4, 132.1, 131.3, 129.7, 129.6, 129.4, 125.2, 122.3, 109.4, 29.8, 29.6, 25.7, 25.1, 23.5, 22.6 ppm; IR (KBr): 3440, 2968, 2930, 2871, 1707, 1602, 1468, 1389, 1367, 1327, 1233, 1202, 1060, 996, 937, 838, 806, 755, 695, 558 –1 + cm ; ESI-HRMS (m/z): [M–I] calcd for C32H39IN3 592.2183, found 592.2180.

S15

5-Iodo-4-phenyl-1,3-bis-(2,4,6-trimethylphenyl)-1H-1,2,3-triazolium iodide (5bf-I) Yield: 63% (161 mg); yellowish solid; 1H NMR (400 MHz, Me Me CDCl3) δ: 7.53 (tt, J = 7.3, 1.6 Hz, 1H), 7.45 (dd, J = 8.0, 7.3 Hz, N Me I I 2H), 7.41 (dd, J = 8.0, 1.6 Hz, 2H), 7.12 (s, 2H), 7.03 (s, 2H), N N Me 2.43 (s, 3H), 2.35 (s, 3H), 2.09 (s, 6H), 2.02 (s, 6H) ppm; 13C Me NMR (100 MHz, CDCl3) δ: 147.4, 143.4, 143.3, 134.4, 134.3, Me 5bf-I 132.4, 131.6, 130.4, 130.3, 130.0, 129.8, 129.3, 122.0, 101.4, 21.5, 21.4, 17.6, 17.6 ppm; IR (KBr): 3643, 3444, 3032, 2980, 2953, 2923, 2360, 1606, 1477, 1447, 1382, 1289, 1210, 1125, 996, 845, 773, 724, 694, –1 + 558 cm ; ESI-HRMS (m/z): [M–I] calcd for C26H27IN3 508.1244, found 508.1271.

5-Iodo-1,3,4-triphenyl-1H-1,2,3-triazolium iodide (5cf-I) 1 Yield: 18% (38.9 mg); purple solid; H NMR (400 MHz, CDCl3) δ: 8.22–8.16 (m, 2H), 7.61–7.46 (m, 7H), 7.45–7.36 (m, 3H), N 13 I I 7.33–7.20 (m, 3H) ppm; C NMR (100 MHz, CDCl3) δ: 155.7, N N 137.2, 136.2, 130.8, 129.8, 129.3, 128.6, 128.2, 127.9, 127.9, 126.8, 125.2, 121.4, 118.8 ppm; IR (KBr): 3447, 3060, 1595, 1462, 1311, 5cf-I 1291, 1203, 1155, 1070, 1027, 958, 916, 841, 698, 654, 505, 405 –1 + cm ; ESI-HRMS (m/z): [M–I] calcd for C20H15IN3 424.0305, found 424.0302.

1-(2,6-Diisopropylphenyl)-5-iodo-3-methyl-4phenyl-1H-1,2,3-triazolium iodide (5ag-I) 1 Yield: 11% (25.3 mg); yellowish solid; H NMR (400 MHz, CDCl3) δ:

Me 7.84 (dd, J = 7.3, 1.3 Hz, 2H), 7.66–7.56 (m, 2H), 7.51 (dd, J = 7.7, 7.3 N I I Hz, 2H), 7.33 (d, J = 7.8 Hz, 2H), 4.31 (s, 3H), 2.22 (seq, J = 6.7 Hz, N N i-Pr 13 i-Pr 2H), 1.10 (d, J = 6.7 Hz, 6H), 1.09 (d, J = 6.7 Hz, 6H) ppm; C NMR

(100 MHz, CDCl3) δ: 146.5, 145.7, 132.9, 132.1, 131.4, 131.1, 129.7, 5ag-I 125.0, 122.6, 107.2, 40.1, 29.4, 25.7, 23.0 ppm; IR (KBr): 3426, 2964, 2928, 2870, 1466, 1318, 1283, 1058, 1023, 756, 697, 418 cm–1; ESI-HRMS (m/z): + [M–I] calcd for C21H25IN3 446.1088, found 446.1095.

S16 1,3-Bis-(2,6-diisopropylphenyl)-5-iodo-4-phenyl-1H-1,2,3-triazolium hexafluorophosphate (5af-PF6) Yield: 71% (209 mg); yellowish solid; 1H NMR (400 MHz, i-Pr CD3CN) δ: 7.78 (t, J = 7.8 Hz, 1H), 7.64 (t, J = 7.8 Hz, 1H), N i-Pr I PF6 7.61–7.57 (m, 1H), 7.57 (d, J = 7.8 Hz, 2H), 7.55–7.48 (m, 4H), 7.42 N N i-Pr i-Pr (d, J = 7.8 Hz, 2H), 2.45–2.31 (m, 4H), 1.34 (d, J = 6.8 Hz, 6H), 1.15 (d, J = 6.8 Hz, 6H), 1.09 (d, J = 6.8 Hz, 6H), 1.03 (d, J = 6.8 Hz, 6H) 5af-PF 6 13 ppm; C NMR (100 MHz, CD3CN) δ: 149.4, 146.7, 146.6, 134.5, 134.3, 133.1, 131.9, 131.1, 130.1, 130.1, 126.4, 126.3, 123.3, 103.7, 30.0, 29.9, 26.1, 25.4, 23.6, 22.5 ppm; IR (KBr): 3453, 2968, 2931, 2872, 1706, 1468, 1389, 1367, 1327, 1201, 1060, 996, 848, 808, 756, 695, 558 cm–1; ESI-HRMS (m/z): [M–I]+ calcd for

C32H39IN3 592.2183, found 592.2179.

1,3-Bis-(2,6-diisopropylphenyl)-5-iodo-4-(4-trifluoromethylphenyl)-1H-1,2,3-triazo lium tetrafluoroborate (5aa-BF4) CF 1 3 Yield: 79% (294 mg); white solid; H NMR (400 MHz, CDCl3) δ: 7.80–7.68 (m, 5H), 7.63 (t, J = 7.9 Hz, 1H), 7.47 (d, J = 7.8Hz, 2H), i-Pr

N 7.35 (d, J = 7.9 Hz, 2H), 2.40 (seq, J = 6.5 Hz, 2H), 2.29 (seq, J = i-Pr I BF4 N N 6.7 Hz, 2H), 1.39 (d, J = 6.5 Hz, 6H), 1.19 (d, J = 6.7 Hz, 6H), 1.17 i-Pr i-Pr (d, J = 6.7 Hz, 6H), 1.10 (d, J = 6.5 Hz, 6H) ppm; 13C NMR (100

5aa-BF4 MHz, CDCl3) δ:147.6, 145.6, 145.3, 133.8, 133.7, 133.6 (q, J = 33 Hz), 130.8, 130.4, 128.6, 126.3 (q, J = 3.6 Hz), 125.3, 125.3, 125.1 (q, J = 1.0 Hz), 123.1 (q, J = 273 Hz), 94.6, 29.4, 29.4, 25.7, 25.0, 23.1, 22.3 ppm; 19F NMR (376 MHz,

CDCl3) δ 51.1 (s, 3F), –37.6 (s, 4F) ; IR (KBr): 3430, 2971, 1625, 1468, 1389, 1367, 1325, 1209, 1167, 1133, 1084, 1065, 855, 802, 753, 698, 603, 521, 472, 458, 436, 422, –1 + 410 cm ; ESI-HRMS (m/z): [M–BF4] calcd for C33H38F3IN3 660.2057, found 660.2055.

S17 Theoretical Study

The Gaussian 09 program package5 was used for all DFT calculations. For geometry optimization, we employed the M06-2X functional6 combined with the SDD (Stuttgart/Dresden pseudopotentials)7 and 6-31G ** basis sets for I atoms and the other atoms, respectively. Solvent effects of dichloromethane (ε = 8.93) were evaluated using the polarizable continuum model (PCM) for all calculations.8 After geometry optimizations, we performed vibrational analyses to confirm that an optimized geometry corresponds to a local minimum that has no imaginary frequency or a transition state that has only one imaginary frequency. An appropriate connection between a reactant and a product was confirmed by quasi-IRC (qIRC) calculations. In the qIRC calculation, the geometry of a transition state was first shifted by perturbing the geometries very slightly along the reaction coordinate, and then released for equilibrium optimization. This approach provides qualitatively identical results with IRC calculations at a considerably lower computational cost. To determine the energy profile of the proposed reaction, we performed single-point energy calculations at the optimized geometries using the SDD and 6-311+G** basis sets for I atoms and the other atoms, respectively. The solvent effects of dichloromethane (ε = 8.93) were evaluated using the PCM. For the C–C bond formation between acetaldehyde and trimethylsilyl isocyanide without catalyst, we cannot locate any minimum corresponding the alkoxide product complex using the 6-31G ** basis set because of instability of the alkoxide species without the catalysts (Fig. S5). The single point energy calculation using 6-31G ** basis set provide the minimum corresponding the alkoxide product complex in the potential energy curve. We confirmed that the potential energy curve obtained with partial geometry optimization/single point energy calculation using 6-31G**/6-311+G** basis sets is consistent with that using 6-311+G**/6-311+G** basis sets (Fig. S5). We performed geometry optimization and single-point energy calculation for the no catalytic C–C bond formation using 6-311+G** basis set (Fig. S6). The solvent effects of dichloromethane (ε = 8.93) were evaluated using the PCM.

S18

Fig. S3 Optimized structures of catalysts (Cat) reactant complexes (RC), local minimums (LM), transition states (TS), and product complexes (PC) for the C–C bond formations. Bond distances are in angstrom.

S19

Fig. S4 Relative energy diagrams for the C–C bond formation between acetaldehyde and trimethylsilyl isocyanide. Energies are in kcal/mol.

Fig. S5 Calculated potential-energy curves for the C–C bond formation between acetaldehyde and trimethylsilyl isocyanide. The partial geometry optimization/single-point energy calculation was performed using 6-31G**/6-31G** basis sets (blue square), 6-31G**/6-311+G** basis sets (red triangle) and 6-311+G**/6-311+G** basis sets (black circle). The potential-energy curve

S20 (6-31G**/6-311+G**) is almost consistent with that using the 6-311+G**/6-311+G** basis. The solvent effects of dichloromethane (ε = 8.93) were evaluated using the PCM.

Fig. S6 Relative energy diagrams for the C–C bond formation without catalysts. The geometry optimization and single-point energy calculation were performed using 6-311+G** basis set. The solvent effects of dichloromethane (ε = 8.93) were evaluated using the PCM. Energies are in kcal/mol and bond distances are in angstrom.

S21

Table S1 Cartesian coordinates of acetaldehyde. Units are angstrom C 2.540780 4.095824 0.317789 O 3.412714 3.536688 -0.307126 H 1.798578 3.505207 0.891743 C 2.372102 5.584824 0.385830 H 1.377878 5.855612 0.017211 H 2.424492 5.909038 1.429834 H 3.142355 6.082707 -0.203081

Table S2 Cartesian coordinates of trimethylsilyl isocyanide. Units are angstrom Si -1.274883 1.188456 0.230688 C -0.502731 3.769777 -0.997257 N -0.810284 2.744366 -0.511596 C -0.767168 -0.130696 -0.984392 H -1.024519 -1.119953 -0.594409 H -1.276814 0.001161 -1.942331 H 0.311345 -0.104526 -1.160563 C -3.120829 1.271634 0.480014 H -3.481255 0.344237 0.934873 H -3.388683 2.101527 1.139097 H -3.638012 1.406971 -0.473489 C -0.333342 1.091125 1.837433 H -0.573973 0.161486 2.361383 H 0.745023 1.112879 1.659764 H -0.592376 1.927856 2.491486

Table S3 Cartesian coordinates of Cat1. Units are angstrom N 2.171816 -2.263192 -1.241122 C 2.610123 -1.398248 -0.293008 C 2.962346 -2.174318 0.788221 N 2.708640 -3.441272 0.375452 N 2.224023 -3.502527 -0.835617 I 2.612742 0.667197 -0.497955 C 2.806690 -4.656833 1.176646 H 2.660433 -5.501313 0.507357

S22 H 3.791988 -4.700141 1.638923 H 2.019542 -4.628205 1.933137 C 3.444745 -1.834937 2.149332 H 2.716767 -2.174617 2.891625 H 4.410204 -2.303670 2.354192 H 3.552993 -0.754116 2.239553 C 1.618919 -1.961252 -2.559068 H 1.457291 -2.911809 -3.061191 H 0.674091 -1.432391 -2.427448 H 2.330644 -1.349410 -3.111877 I -0.617998 -2.441546 1.399847

Table S4 Cartesian coordinates of Cat2. Units are angstrom N 2.184871 -2.207070 -1.247428 C 2.638245 -1.342992 -0.310145 C 2.969584 -2.117730 0.774315 N 2.690220 -3.385299 0.373629 N 2.206183 -3.444291 -0.838787 H 2.675044 -0.277455 -0.466875 C 2.771742 -4.595880 1.182212 H 2.579461 -5.441594 0.526391 H 3.767339 -4.668371 1.618483 H 2.006385 -4.535899 1.958953 C 3.463818 -1.782588 2.134339 H 2.730735 -2.101284 2.881142 H 4.417014 -2.275043 2.341468 H 3.599629 -0.705177 2.217799 C 1.624438 -1.891642 -2.559522 H 1.666660 -2.794956 -3.163174 H 0.591887 -1.567480 -2.428757 H 2.221111 -1.101319 -3.010437 I -0.648368 -2.526529 1.443394

Table S5 Cartesian coordinates of Cat3. Units are angstrom N 1.993568 -2.350298 -1.276646 C 2.265228 -1.441464 -0.309056

S23 C 2.517070 -2.170234 0.830922 N 2.376867 -3.458193 0.429179 N 2.055795 -3.574847 -0.831278 I 2.192840 0.614005 -0.585694 C 2.526204 -4.652044 1.255295 H 2.344255 -5.512719 0.616051 H 3.538427 -4.681855 1.657976 H 1.787553 -4.603412 2.053478 C 2.830493 -1.779264 2.226089 H 2.041421 -2.152117 2.882425 H 3.794574 -2.186306 2.540450 H 2.860156 -0.692643 2.300855 C 1.541361 -2.108366 -2.642607 H 1.514646 -3.071109 -3.147190 H 0.543771 -1.669862 -2.598715 H 2.239896 -1.433992 -3.135878 P -1.019831 -2.126913 1.447905 F -2.051269 -1.043310 0.839957 F 0.045687 -3.214471 2.049739 F -0.393565 -2.370677 -0.038632 F -1.614184 -1.896596 2.932478 F -2.082318 -3.315547 1.189488 F 0.074557 -0.951365 1.702207

Table S6 Cartesian coordinates of RC1. Units are angstrom N 2.345583 -2.463295 -1.134760 C 2.849001 -1.605847 -0.210548 C 3.255850 -2.400413 0.838647 N 2.963640 -3.662297 0.434427 N 2.406635 -3.707844 -0.745232 I 2.903746 0.473830 -0.414207 C 3.099173 -4.884453 1.218410 H 2.858629 -5.719991 0.565431 H 4.122810 -4.964246 1.582396 H 2.390160 -4.834566 2.047387 C 3.829593 -2.080722 2.169312

S24 H 3.130662 -2.381170 2.955556 H 4.781142 -2.594915 2.324153 H 3.996303 -1.006322 2.246011 C 1.715555 -2.145356 -2.413188 H 1.533961 -3.087498 -2.924478 H 0.773945 -1.629499 -2.218026 H 2.386529 -1.514284 -2.994592 I -0.352055 -2.850288 1.594984 Si -1.534448 1.547750 0.169861 C -0.592149 4.131023 -0.944992 N -0.979707 3.115170 -0.501581 C -1.128543 0.286404 -1.142488 H -1.133330 -0.717329 -0.703417 H -1.854715 0.323718 -1.959114 H -0.134082 0.481422 -1.553356 C -3.367149 1.730995 0.456865 H -3.772565 0.791564 0.845031 H -3.575236 2.518710 1.185612 H -3.889633 1.969704 -0.473025 C -0.589216 1.336436 1.761516 H -0.922170 0.423876 2.265483 H 0.484098 1.235089 1.578495 H -0.756583 2.188994 2.426371 C 2.306015 3.912777 0.241161 O 2.968836 3.268329 -0.548435 H 1.626845 3.392456 0.943932 C 2.343899 5.402574 0.338493 H 1.340470 5.786646 0.131811 H 2.603649 5.692298 1.361116 H 3.060955 5.814370 -0.371222

Table S7 Cartesian coordinates of RC2. Units are angstrom N 2.571073 -1.402238 -0.830149 C 2.563770 -0.906418 0.429587 C 2.399884 -1.997139 1.250865 N 2.330681 -3.050729 0.394798

S25 N 2.426904 -2.698293 -0.861028 H 2.673062 0.149462 0.629552 C 2.131440 -4.452973 0.746558 H 2.140535 -5.025063 -0.178041 H 2.940744 -4.773261 1.402620 H 1.161764 -4.540729 1.240310 C 2.296135 -2.131663 2.726935 H 1.307985 -2.522381 2.989816 H 3.063445 -2.806971 3.114050 H 2.423743 -1.153482 3.190087 C 2.728314 -0.658641 -2.080059 H 3.593213 -1.050539 -2.612881 H 1.823406 -0.777446 -2.675157 H 2.875819 0.387309 -1.813289 I -1.341932 -2.814840 1.203004 Si -0.935991 1.350743 0.661980 C -0.651076 4.278959 0.235099 N -0.758853 3.120737 0.397658 C -0.330637 0.582442 -0.926708 H -0.245707 -0.502142 -0.798699 H -1.023692 0.783095 -1.748320 H 0.648208 0.997420 -1.184269 C -2.751055 1.093903 0.990025 H -2.938230 0.032449 1.175535 H -3.072167 1.664493 1.865723 H -3.348910 1.408476 0.130324 C 0.152833 0.982751 2.131553 H 0.189470 -0.101073 2.283582 H 1.164845 1.364197 1.964964 H -0.248263 1.445253 3.037507 C 2.356423 3.284947 -0.385945 O 2.575117 2.108288 -0.172205 H 2.329484 3.999560 0.456336 C 2.114725 3.855495 -1.745270 H 1.149989 4.371843 -1.741468 H 2.881325 4.606363 -1.961823

S26 H 2.128378 3.071337 -2.503261

Table S8 Cartesian coordinates of RC3. Units are angstrom N 2.171920 -2.317178 -1.201895 C 2.625681 -1.622243 -0.128501 C 2.754479 -2.551338 0.880513 N 2.373259 -3.719980 0.306011 N 2.018228 -3.587566 -0.943725 I 3.037282 0.425877 -0.124124 C 2.285973 -5.029072 0.945828 H 2.056066 -5.755138 0.169697 H 3.244447 -5.259643 1.410227 H 1.492621 -4.989093 1.690464 C 3.191577 -2.424705 2.292730 H 2.392572 -2.763737 2.954032 H 4.093661 -3.013999 2.476684 H 3.406535 -1.378368 2.509778 C 1.838338 -1.811496 -2.530625 H 1.527247 -2.664271 -3.128877 H 1.024841 -1.091342 -2.436599 H 2.719208 -1.338445 -2.964441 P -0.762660 -2.233281 1.754765 F -1.805341 -1.174620 1.089428 F 0.287041 -3.295379 2.414435 F -0.255830 -2.668919 0.270427 F -1.238045 -1.775404 3.229147 F -1.896686 -3.379676 1.713974 F 0.395085 -1.091475 1.776571 Si -1.518561 1.578073 0.268676 C -1.113725 4.331966 -0.792396 N -1.283645 3.250020 -0.368760 C -0.649624 0.505033 -0.996061 H -0.200403 -0.356288 -0.496602 H -1.369618 0.140982 -1.735248 H 0.125294 1.075597 -1.514955 C -3.371886 1.369983 0.306823

S27 H -3.623836 0.367390 0.658866 H -3.826584 2.101064 0.980949 H -3.798197 1.508467 -0.690409 C -0.757763 1.644613 1.970965 H -1.060043 0.767119 2.545685 H 0.334480 1.643145 1.921930 H -1.087797 2.549393 2.489315 C 2.308787 3.810308 0.077145 O 3.347160 3.224205 -0.160150 H 1.400965 3.234231 0.344149 C 2.153871 5.293910 0.035489 H 1.301389 5.545688 -0.602595 H 1.907627 5.649136 1.041865 H 3.068311 5.768956 -0.318805

Table S9 Cartesian coordinates of LM2. Units are angstrom Si -1.943823 0.584201 0.247114 C 0.425029 2.293600 0.817559 N -0.498748 1.606216 0.592104 C -1.243888 -1.124418 -0.015957 H -2.062033 -1.834740 -0.165519 H -0.598574 -1.152034 -0.899004 H -0.665545 -1.442691 0.856752 C -2.700522 1.340472 -1.277343 H -3.585130 0.764394 -1.563946 H -3.002365 2.374371 -1.088990 H -1.991564 1.330651 -2.109803 C -3.001245 0.726749 1.773773 H -3.911584 0.136312 1.635059 H -2.471946 0.349973 2.653255 H -3.285026 1.766633 1.956834 C 3.219221 3.452690 0.186956 O 3.568583 2.819332 -0.789677 H 3.307498 3.010346 1.196834 C 2.669990 4.842052 0.129798 H 1.668559 4.833341 0.568704

S28 H 3.292401 5.504319 0.739353 H 2.632642 5.196489 -0.900167 N 3.851566 -0.633697 0.103466 C 4.934189 0.057260 -0.325557 C 5.971662 -0.844723 -0.310138 N 5.403173 -1.999175 0.133394 N 4.124593 -1.876724 0.384887 H 4.860980 1.100251 -0.602855 C 6.061858 -3.287088 0.336710 H 5.301880 -3.993025 0.662428 H 6.504782 -3.613236 -0.604027 H 6.831049 -3.176672 1.100998 C 7.409052 -0.727944 -0.672444 H 8.044733 -0.984601 0.178426 H 7.654193 -1.394950 -1.502782 H 7.625707 0.295934 -0.973674 C 2.496287 -0.117136 0.297957 H 1.794246 -0.924121 0.098275 H 2.391063 0.237527 1.323612 H 2.354500 0.708491 -0.396495 I -5.346349 -1.813752 -0.652429

Table S10 Cartesian coordinates of LM3. Units are angstrom Si -1.409593 0.744892 0.286827 C 0.003727 3.364696 0.125263 N -0.566659 2.342019 0.199333 C -0.226212 -0.388076 -0.619863 H -0.722476 -1.322810 -0.884546 H 0.137719 0.100046 -1.529360 H 0.628845 -0.616844 0.024146 C -3.012381 1.043584 -0.614566 H -3.569946 0.111103 -0.710205 H -3.630856 1.758503 -0.065009 H -2.811549 1.452380 -1.608894 C -1.506759 0.419739 2.119806 H -1.929164 -0.567629 2.308067

S29 H -0.506024 0.481160 2.558562 H -2.142427 1.164095 2.607175 C 2.668707 4.772310 -0.326517 O 3.121732 4.143453 -1.265040 H 2.631509 4.314509 0.677821 C 2.142780 6.164913 -0.436414 H 1.088282 6.146517 -0.145271 H 2.668824 6.813927 0.269608 H 2.249819 6.538204 -1.454638 N 3.036931 -1.586826 -1.430070 C 3.263964 -0.634891 -0.487053 C 3.385774 -1.324900 0.700836 N 3.218585 -2.628065 0.350868 N 3.010124 -2.792723 -0.928282 I 3.288272 1.423065 -0.861105 C 3.261819 -3.792820 1.233194 H 2.990741 -4.660687 0.637078 H 4.271194 -3.901421 1.629535 H 2.547009 -3.649250 2.042511 C 3.609014 -0.869224 2.096867 H 2.700576 -0.997111 2.692375 H 4.417509 -1.433365 2.567164 H 3.876926 0.187336 2.094841 C 2.817823 -1.402158 -2.863825 H 2.685756 -2.390344 -3.297163 H 1.921716 -0.798204 -3.007687 H 3.686445 -0.904221 -3.293504 P -4.017593 -2.312857 1.052466 F -3.771765 -3.838973 0.570863 F -4.239304 -0.776213 1.524971 F -5.431669 -2.730919 1.713103 F -2.584391 -1.887666 0.384780 F -4.753261 -1.979253 -0.354497 F -3.251840 -2.623826 2.449851

Table S11 Cartesian coordinates of TS1. Units are angstrom

S30 Si -1.976457 0.972822 0.661852 C -0.074334 3.226260 0.135422 N -0.839254 2.378247 0.341619 C -1.086576 -0.439957 -0.163365 H -1.683882 -1.349810 -0.059707 H -0.946448 -0.222974 -1.226873 H -0.108109 -0.601559 0.300118 C -3.551736 1.502834 -0.166510 H -4.289602 0.703124 -0.059637 H -3.949055 2.409972 0.296206 H -3.389804 1.691812 -1.230931 C -2.033634 0.900925 2.517870 H -2.708966 0.095095 2.817790 H -1.042034 0.699308 2.931790 H -2.404318 1.841651 2.933148 C 1.380237 4.042768 -0.505068 O 1.771506 3.345915 -1.509677 H 1.960959 3.968460 0.435597 C 0.913287 5.463851 -0.770665 H 0.472079 5.917450 0.119853 H 1.788742 6.045094 -1.071403 H 0.192177 5.473936 -1.589773 N 2.705660 -2.083919 -1.025788 C 3.150319 -0.948807 -0.422203 C 4.014065 -1.393726 0.557868 N 4.000748 -2.748909 0.443453 N 3.214280 -3.172495 -0.510130 I 2.552216 1.029871 -0.955237 C 4.745495 -3.713118 1.248659 H 4.490555 -4.706089 0.886247 H 5.812905 -3.527734 1.130282 H 4.454792 -3.603575 2.293282 C 4.824419 -0.667870 1.570145 H 4.502790 -0.924054 2.583040 H 5.885093 -0.911572 1.470265 H 4.700462 0.405720 1.427901

S31 C 1.757536 -2.195124 -2.132573 H 1.658737 -3.251532 -2.370216 H 0.799231 -1.782142 -1.816846 H 2.145362 -1.641864 -2.987265 I -4.452997 -2.234313 1.357405

Table S12 Cartesian coordinates of TS2. Units are angstrom Si -3.598920 3.454373 2.498930 C -5.930585 5.313264 2.832578 N -5.037675 4.582827 2.710490 C -2.180041 4.561985 2.974649 H -1.238957 4.027994 2.818850 H -2.172691 5.465528 2.357697 H -2.243405 4.847389 4.028557 C -3.694863 3.016154 0.696045 H -2.849719 2.369147 0.445819 H -4.622892 2.482832 0.473934 H -3.647369 3.914256 0.074644 C -3.985276 2.079378 3.689014 H -3.184233 1.336433 3.648592 H -4.060476 2.458916 4.711549 H -4.928048 1.593116 3.424285 C -6.886224 6.735130 2.757433 O -6.221823 7.591670 2.060861 H -6.970583 6.912722 3.854828 C -8.222597 6.244659 2.201595 H -8.649180 5.437356 2.802674 H -8.908930 7.095389 2.206535 H -8.095041 5.911882 1.169464 N -4.203068 8.992869 4.401631 C -5.371878 9.558031 4.014452 C -5.516578 10.664941 4.819158 N -4.412048 10.652158 5.614678 N -3.614945 9.642987 5.367091 H -5.951754 9.103051 3.207709 C -4.056956 11.616212 6.651960

S32 H -3.115344 11.292646 7.088644 H -3.947279 12.602521 6.201411 H -4.840020 11.630987 7.409780 C -6.572983 11.709264 4.898409 H -7.024505 11.734299 5.893413 H -6.161480 12.697900 4.679719 H -7.351269 11.488961 4.169014 C -3.601774 7.773277 3.859411 H -2.556507 7.973333 3.629573 H -3.681360 6.981920 4.605521 H -4.174103 7.524769 2.963402 I -0.404416 0.981169 2.051498

Table S13 Cartesian coordinates of TS3. Units are angstrom Si -3.359627 3.664540 2.514521 C -6.161396 4.718520 2.200418 N -5.094401 4.278176 2.321795 C -2.587562 5.194225 3.255811 H -1.549115 5.006580 3.532308 H -2.621238 6.010451 2.527231 H -3.147678 5.497743 4.145991 C -2.924703 3.325624 0.739010 H -1.861116 3.107567 0.644957 H -3.484245 2.462870 0.368843 H -3.177104 4.196617 0.127676 C -3.622000 2.245645 3.687477 H -2.666978 1.820345 3.995515 H -4.168825 2.594217 4.568239 H -4.207693 1.459787 3.203273 C -7.463063 5.943865 1.865648 O -6.869347 6.960266 1.366401 H -7.817928 6.009195 2.912137 C -8.427188 5.175766 0.978485 H -8.756789 4.247231 1.449819 H -9.295186 5.818288 0.807377 H -7.961143 4.959444 0.015608

S33 N -3.254390 9.664786 4.621503 C -4.600307 9.617233 4.435289 C -5.107094 10.531350 5.336727 N -4.014984 11.034483 5.971888 N -2.893615 10.515961 5.546356 I -5.607950 8.385697 3.012829 C -3.991393 12.048040 7.022976 H -2.951907 12.206551 7.299680 H -4.426839 12.970091 6.638223 H -4.561798 11.687432 7.878646 C -6.496918 10.959838 5.641678 H -6.749724 10.749893 6.684244 H -6.623609 12.030494 5.462026 H -7.190562 10.416186 5.000214 C -2.226525 8.892601 3.927317 H -1.262966 9.209698 4.318717 H -2.388788 7.832426 4.120743 H -2.292502 9.094953 2.858402 P -0.121515 1.433599 2.434273 F 1.323956 1.928917 2.961887 F -1.587383 0.968920 1.914333 F 0.487040 -0.010883 2.047965 F -0.750574 2.900982 2.824418 F 0.217104 1.997853 0.951458 F -0.490430 0.904534 3.923266

Table S14 Cartesian coordinates of acetaldehyde which was optimized by using 6-311+G** basis set. Units are angstrom C 2.540144 4.099154 0.318262 O 3.406353 3.535593 -0.304194 H 1.801291 3.508019 0.890897 C 2.375350 5.584915 0.383716 H 1.380061 5.849841 0.016906 H 2.423618 5.903426 1.428541 H 3.142084 6.088952 -0.201929

S34 Table S15 Cartesian coordinates of trimethylsilyl isocyanide which was optimized by using 6-311+G** basis set. Units are angstrom Si -1.277696 1.179718 0.235123 C -0.505279 3.759896 -0.994690 N -0.811887 2.741180 -0.510115 C -0.767568 -0.128982 -0.983221 H -1.027975 -1.118654 -0.599437 H -1.273867 0.009806 -1.940710 H 0.310604 -0.102476 -1.154231 C -3.119246 1.270338 0.480229 H -3.482176 0.343742 0.932321 H -3.384281 2.099345 1.139726 H -3.632439 1.408402 -0.473764 C -0.333865 1.092371 1.835981 H -0.572750 0.165875 2.364074 H 0.742731 1.114017 1.654492 H -0.592806 1.931721 2.484923

Table S16 Cartesian coordinates of RC4 which was optimized by using 6-311+G** basis set. Units are angstrom Si 1.394637 -0.036493 0.251021 C -0.752906 0.580935 2.200257 N 0.081437 0.342072 1.417195 C 1.608901 1.492985 -0.781676 H 2.399317 1.336209 -1.520315 H 0.683242 1.728520 -1.310806 H 1.887703 2.346262 -0.159452 C 0.802580 -1.509651 -0.716729 H 1.607852 -1.874452 -1.359969 H 0.503553 -2.322659 -0.051270 H -0.043880 -1.237289 -1.349637 C 2.877690 -0.419311 1.309406 H 3.731920 -0.675185 0.677210 H 3.152379 0.441654 1.922584 H 2.676589 -1.265655 1.969829 C -2.393987 0.448727 -0.615339

S35 O -1.662624 0.728653 -1.535182 H -2.769401 1.245548 0.051930 C -2.850903 -0.939120 -0.292368 H -2.520345 -1.193831 0.718738 H -3.943950 -0.961982 -0.286636 H -2.461489 -1.658623 -1.011001

Table S17 Cartesian coordinates of TS4 which was optimized by using 6-311+G** basis set. Units are angstrom Si -1.035638 1.088855 0.467499 C 0.887504 3.361189 0.461492 N 0.130878 2.488584 0.477132 C -0.350041 -0.059470 -0.816589 H -0.981353 -0.948820 -0.888522 H -0.323834 0.421222 -1.796347 H 0.661214 -0.378170 -0.556524 C -2.661078 1.858990 0.011810 H -3.435550 1.088494 -0.019509 H -2.957976 2.611585 0.744885 H -2.608108 2.328875 -0.972338 C -0.963580 0.429508 2.200371 H -1.645139 -0.419214 2.299045 H 0.043927 0.087819 2.445544 H -1.261747 1.192003 2.922720 C 2.176848 4.326365 0.137759 O 2.900207 3.702336 -0.739026 H 2.592478 4.421413 1.162875 C 1.555353 5.668695 -0.270913 H 0.893404 6.067671 0.502244 H 2.377261 6.368930 -0.431102 H 1.006272 5.559141 -1.207605

Table S18 Cartesian coordinates of PC4 which was optimized by using 6-311+G** basis set. Units are angstrom Si 1.710108 -0.004086 -0.039626 C -1.239312 -0.083894 0.364593

S36 N -0.095077 -0.069529 0.218982 C 1.958709 1.515622 -1.071371 H 3.024233 1.649669 -1.274750 H 1.436489 1.429845 -2.026121 H 1.595346 2.404706 -0.552388 C 2.094470 -1.594381 -0.914001 H 3.166384 -1.648014 -1.120342 H 1.821736 -2.455609 -0.300964 H 1.561058 -1.656184 -1.864678 C 2.404605 0.112824 1.676523 H 3.495760 0.152836 1.628083 H 2.052613 1.016012 2.178786 H 2.121891 -0.755552 2.274797 C -2.791370 0.194511 0.373017 O -2.983976 1.304912 -0.301090 H -2.991617 0.235216 1.465626 C -3.443918 -1.084134 -0.180150 H -3.177966 -1.970711 0.402031 H -4.524327 -0.938842 -0.132613 H -3.158925 -1.228301 -1.223756

S37 5. NMR Spectra Data CF3

i-Pr

N 1 i-Pr H PF6 H NMR N N i-Pr i-Pr

3aa-PF6

S38 CF3

i-Pr

N 13 i-Pr H PF6 C NMR N N i-Pr i-Pr

3aa-PF6

S39 Me

i-Pr

N 1 i-Pr H PF6 H NMR N N i-Pr i-Pr

3ab-PF6

S40 Me

i-Pr

N 13 i-Pr H PF6 C NMR N N i-Pr i-Pr

3ab-PF6

S41 OMe

i-Pr

N 1 i-Pr H PF6 H NMR N N i-Pr i-Pr

3ac-PF6

S42 OMe

i-Pr

N 13 i-Pr H PF6 C NMR N N i-Pr i-Pr

3ac-PF6

S43

i-Pr i-Pr i-Pr

N 1 i-Pr H PF6 H NMR N N i-Pr i-Pr

3ad-PF6

S44 i-Pr i-Pr i-Pr

N 13 i-Pr H PF6 C NMR N N i-Pr i-Pr

3ad-PF6

S45 Me

Me i-Pr Me

N 1 i-Pr H PF6 H NMR N N i-Pr i-Pr

3ae-PF6

S46 Me

Me i-Pr Me

N 13 i-Pr H PF6 C NMR N N i-Pr i-Pr

3ae-PF6

S47

i-Pr

N 1 i-Pr H PF6 H NMR N N i-Pr i-Pr

3af-PF6

S48

i-Pr

N 13 i-Pr H PF6 C NMR N N i-Pr i-Pr

3af-PF6

S49

Me Me

N 1 Me H PF6 H NMR N N Me Me

Me

3bf-PF6

S50 Me Me

N 13 Me H PF6 C NMR N N Me Me

Me

3bf-PF6

S51

N 1 H PF6 H NMR N N

3cf-PF6

S52

N 13 H PF6 C NMR N N

3cf-PF6

S53 CF3

i-Pr

N i-Pr I I 1H NMR N N i-Pr i-Pr

5aa-I

S54 CF3

i-Pr

N i-Pr I I 13C NMR N N i-Pr i-Pr

5aa-I

S55 Me

i-Pr

N i-Pr I I 1H NMR N N i-Pr i-Pr

5ab-I

S56 Me

i-Pr

N i-Pr I I 13C NMR N N i-Pr i-Pr

5ab-I

S57 OMe

i-Pr

N i-Pr I I 1H NMR N N i-Pr i-Pr

5ac-I

S58 OMe

i-Pr

N i-Pr I I 13C NMR N N i-Pr i-Pr

5ac-I

S59

i-Pr i-Pr i-Pr N i-Pr I I 1H NMR N N i-Pr i-Pr

5ad-I

S60

i-Pr i-Pr i-Pr N i-Pr I I 13C NMR N N i-Pr i-Pr

5ad-I

S61 Me

Me i-Pr Me N i-Pr I I 1H NMR N N i-Pr i-Pr

5ae-I

S62 Me

Me i-Pr Me N i-Pr I I 13C NMR N N i-Pr i-Pr

5ae-I

S63

i-Pr

N i-Pr I I 1H NMR N N i-Pr i-Pr

5af-I

S64

i-Pr

N i-Pr I I 13C NMR N N i-Pr i-Pr

5af-I

S65 Me Me

N Me I I 1H NMR N N Me Me

Me 5bf-I

S66 Me Me

N Me I I 13C NMR N N Me Me

Me 5bf-I

S67 N I I 1H NMR N N

5cf-I

S68 N I I 13C NMR N N

5cf-I

S69

Me N I I 1H NMR N N i-Pr i-Pr

5ag-I

S70

Me N I I 13C NMR N N i-Pr i-Pr

5ag-I

S71

i-Pr

N 1 i-Pr I PF6 H NMR N N i-Pr i-Pr

5af-PF6

S72 i-Pr

N 13 i-Pr I PF6 C NMR N N i-Pr i-Pr

5af-PF6

S73 CF3

i-Pr

N 1 i-Pr I BF4 H NMR N N i-Pr i-Pr

5aa-BF4

S74 CF3

i-Pr

N 13 i-Pr I BF4 C NMR N N i-Pr i-Pr

5aa-BF4

S75 CF3

i-Pr

N 19 i-Pr I BF4 F NMR N N i-Pr i-Pr

5aa-BF4

S76

References [1] N. Nimitsiriwat, V. C. Gibson, E. L. Marshall, P. Takolpockdee, A. K. Tomov, A. J. P. White, D. J. Williams, M. R. J. Elsegood, S. H. Dale, Inorg. Chem., 2007, 46, 9988. [2] R. K. Kumar, M. A. Ali, T. Punniyamurthy, Org. Lett., 2011, 13, 2102. [3] B. Zhou, H. Chen and C. Wang, J. Am. Chem. Soc., 2013, 135, 1264. [4] J. Bouffard, B. K. Keitz, R. Tonner, G. Guisado-Barrios, G. Frenking, R. H. Grubbs, G. Bertrand, Organometallics, 2011, 30, 2617. [5] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Jr. Montgomery, J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09, revision D.01; Gaussian Inc.: Wallingford, CT, 2010. (10) Legault, C. Y. CYLview, 1.0b; Université de Sherbrooke: Sherbrooke (Quebec) Canada, 2009; ́ http://www.cylview.org. [6] Y. Zhao, D. G. Truhlar, Theor. Chem. Acc., 2008, 120, 215. [7] D. Andrae, U. Häußermann, M. Dolg, H. Stoll, H. Preuß, Theor. Chim. Acta, 1990, 77, 123. [8] S. Miertuš, E. Scrocco, J. Tomasi, Chem. Phys., 1981, 55, 117.

S77