E-H (E = B, Si, C) Bond Activation by Tuning Structural and Electronic Properties of Phosphenium Cations

E-H (E = B, Si, C) Bond Activation by Tuning Structural and Electronic Properties of Phosphenium Cations Nemanja Đorđević, Rakesh Ganguly, Milena Petković, and Dragoslav Vidović Email: drasko.vidovic@monash.edu SUPPORTING INFORMATION

1. Multinuclear NMR Spectra [( i Pr2N)2P][BAr Cl 4], [1][BAr Cl 4]: Figure S1. 1 H NMR Spectrum of [1][BAr Cl 4] 2

Figure S2. 13 C{ 1 H} NMR Spectrum of [1][BAr Cl 4] Figure S3. 31 P NMR Spectrum of [1][BAr Cl 4] 3

[{C6H4(MeN)2C}2C. P(N i Pr2)Cl][X], [2a-Cl][X], X = Cl, SbF6: Figure S4. 1 H NMR Spectrum of [2a-Cl]Cl Figure S5. 13 C{ 1 H} NMR Spectrum of [2a-Cl]Cl 4

Figure S6. 31 P NMR Spectrum of [2a-Cl]Cl 5

[{C6H4(MeN)2C}2C. P(Ph)Cl][X], [2b-Cl][X], X = Cl, SbF6: Figure S7. 1 H NMR Spectrum of [2b-Cl]Cl 6

Figure S8. 13 C{ 1 H} NMR Spectrum of [2b-Cl]Cl Figure S9. 31 P NMR Spectrum of [2b-Cl]Cl 7

[{C6H4(MeN)2C}2C. PN i Pr2][BAr Cl 4]2, [2a][BAr Cl 4]2: Figure S10. 1 H NMR Spectrum of [2a][BAr Cl 4] 2 8

Figure S11. 13 C{ 1 H} NMR Spectrum of [2a][BAr Cl 4] 2 Figure S12. 31 P NMR Spectrum of [2a][BAr Cl 4] 2 9

[{C6H4(MeN)2C}2C. PPh][X]2, [2b][X]2, X = AlCl4 and BAr Cl 4: Figure S13. 1 H NMR Spectrum of [2b][AlCl 4] 2 Figure S14. 13 C{ 1 H} NMR Spectrum of [2b][AlCl 4] 2 10

Figure S15. 31 P NMR Spectrum of [2b][AlCl 4] 2 11

[{C6H4(MeN)2C}2C. P(CH2CCH3)2Ph][AlCl4]2, [2b(CH2CCH3)2][AlCl4]2: Figure S16. 1 H NMR Spectrum of [2b(CH2CCH3)2][AlCl 4] 2 Figure S17. 13 C{ 1 H} NMR Spectrum of [2b(CH2CCH3)2][AlCl 4] 2 12

31.15 400 300 200 100 0 100 200 300 400 ppm Figure S18. 31 P{ 1 H} NMR Spectrum of [2b(CH2CCH3)2][AlCl 4] 2 Figure S19. 31 P NMR Spectrum of [2b(CH2CCH3)2][AlCl 4] 2 13

[( i Pr2N)2P(H)(BH2. Py)][BAr Cl 4], [1(H)(BH2. Py)][BAr Cl 4]: Figure S20. 1 H NMR Spectrum of [1(H)(BH2. Py)][BAr Cl 4] Figure S21. 13 C{ 1 H} NMR Spectrum of [1(H)(BH2. Py)][BAr Cl 4] 14

Figure S22. 11 B NMR Spectrum of [1(H)(BH2. Py)][BAr Cl 4] 15

Figure S23. 11 B{ 1 H} NMR Spectrum of [1(H)(BH2. Py)][BAr Cl 4] Figure S24. 31 P NMR Spectrum of [1(H)(BH2. Py)][BAr Cl 4] 16

Figure S25. 31 P{ 1 H} NMR Spectrum of [1(H)(BH2. Py)][BAr Cl 4] 17

[( i Pr2N)2P(H)(BH2. NMe3)][BAr Cl 4], [1(H)(BH2. NMe3)][BAr Cl 4]: Figure S26. 1 H NMR Spectrum of [1(H)(BH2. NMe3)][BAr Cl 4] Figure S27. 13 C{ 1 H} NMR Spectrum of [1(H)(BH2. NMe3)][BAr Cl 4] 18

Figure S28. 11 B NMR Spectrum of [1(H)(BH2. NMe3)][BAr Cl 4] Figure S29. 11 B{ 1 H} NMR Spectrum of [1(H)(BH2. NMe3)][BAr Cl 4] 19

Figure S30. 31 P NMR Spectrum of [1(H)(BH2. NMe3)][BAr Cl 4] Figure S31. 31 P{ 1 H} NMR Spectrum of [1(H)(BH2. NMe3)][BAr Cl 4] 20

Reactions of [2a][BAr Cl 4]2 with H3B. LB (LB = NMe3, Pyridine): Figure S32. 31 P{ 1 H} NMR Spectrum of the reaction between in situ formed [2a][BAr Cl 4] 2 and H 3B. NMe 3 21

Figure S33. 31 P NMR Spectrum of the reaction between in situ formed [2a][BAr Cl 4] 2 and H 3B. NMe 3 Figure S34. 31 P NMR Spectrum of the reaction between in situ formed [2a][BAr Cl 4] 2 and H 3B. Py 22

Figure S35. 31 P{ 1 H} NMR Spectrum of the reaction between in situ formed [2a][BAr Cl 4] 2 and H 3B. Py 23

x10 4 +ESI Scan (rt: 0.734 min) Frag=200.0V Sept23-2016 ND9.d 3.6 3.4 3.2 264.1658 3 2.8 2.6 2.4 2.2 2 1.8 1.6 1.4 1.2 1 264.6675 0.8 263.6628 0.6 0.4 0.2 0 265.1695 263.6 263.8 264 264.2 264.4 264.6 264.8 265 265.2 265.4 265.6 Counts vs. Mass-to-Charge (m/z) Figure S36. HR-MS Spectrum (experimental bottom, and theoretical top right) of [2a(H)(BH2. Py)][BAr Cl 4] 2 24

[{C6H4(MeN)2C}2C. P(H)(BH2. NMe3)N i Pr2][BAr Cl 4]2, [2a(H)(BH2. NMe3)][BAr Cl 4]2: Figure S37. 1 H NMR Spectrum of [2a(H)(BH2. NMe3)][BAr Cl 4] 2 25

Figure S38. 11 B NMR Spectrum of [2a(H)(BH2. NMe3)][BAr Cl 4] 2 Figure S39. 11 B{ 1 H} NMR Spectrum of [2a(H)(BH2. NMe3)][BAr Cl 4] 2 26

Figure S40. 13 C{ 1 H} NMR Spectrum of [2a(H)(BH2. NMe3)][BAr Cl 4] 2 Figure S41. 31 P NMR Spectrum of [2a(H)(BH2. NMe3)][BAr Cl 4] 2 27

Figure S42. 31 P{ 1 H} NMR Spectrum of [2a(H)(BH2. NMe3)][BAr Cl 4] 2 28

x10 6 +ESI Scan (rt: 1.101 min) Frag=150.0V Sept23-2016 ND7.d 3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 253.6837 Figure S43. HR-MS Spectrum (experimental bottom, and theoretical top right) of [2a(H)(BH2. NMe3)][BAr Cl 4] 2 254.1811 254.6833 254.8316 255.1844 253.6 253.8 254 254.2 254.4 254.6 254.8 255 255.2 255.4 Counts vs. Mass-to-Charge (m/z) 29

[{C6H4(MeN)2C}2C. PH2][X], [2. PH2][X], [X] = [AlCl4], [BAr Cl 4]: Figure S44. 1 H NMR Spectrum of [2. PH2][BAr Cl 4] 30

Figure S45. 31 P NMR Spectrum of [2. PH2][BAr Cl 4] Figure S46. 31 P{ 1 H} NMR Spectrum of [2. PH2][BAr Cl 4] 31

Reactions of [2b][BAr Cl 4]2 with BH3. LB (LB = NMe3, Pyridine): Figure S47. 31 P NMR Spectrum of the reaction between in situ formed [2b][BAr Cl 4] 2 and H 3B. NMe 3 32

Figure S48. 31 P{ 1 H} NMR Spectrum of the reaction between in situ formed [2b][BAr Cl 4] 2 and H 3B. NMe 3 Figure S49. 31 P NMR Spectrum of the reaction between in situ formed [2b][BAr Cl 4] 2 and H 3B. Py 33

Figure S50. 31 P{ 1 H} NMR Spectrum of the reaction between in situ formed [2b][BAr Cl 4] 2 and H 3B. Py 34

x10 4 +ESI Scan (rt: 3.003 min) Frag=100.0V Sept23-2016 ND10.d 3.1 3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 252.1271 252 252.2 252.4 252.6 252.8 253 253.2 253.4 253.6 253.8 254 Counts vs. Mass-to-Charge (m/z) Figure S51. HR-MS Spectrum (experimentally obtained bottom, and theoretically predicted top right) of [2b(H)(BH2. Py)][BAr Cl 4] 2 252.6292 253.1362 253.6369 35

[{C6H4(MeN)2C}2C. P(H)(BH2. NMe3)Ph][X]2, [2b(H)(BH2. NMe3)][X]2, X = AlCl4, BAr Cl 4: Figure S52. 1 H NMR Spectrum of [2b(H)(BH2. NMe3)][BAr Cl 4] 2 36

Figure S53. 11 B NMR Spectrum of [2b(H)(BH2. NMe3)][BAr Cl 4] 2 Figure S54. 11 B{ 1 H} NMR Spectrum of [2b(H)(BH2. NMe3)][BAr Cl 4] 2 37

Figure S55. 13 C{ 1 H} NMR Spectrum of [2b(H)(BH2. NMe3)][BAr Cl 4] 2 Figure S56. 31 P NMR Spectrum of [2b(H)(BH2. NMe3)][BAr Cl 4] 2 38

Figure S57. 31 P{ 1 H} NMR Spectrum of [2b(H)(BH2. NMe3)][BAr Cl 4] 2 39

x10 5 +ESI Scan (rt: 0.800 min) Frag=50.0V Sept23-2016 ND3.d 4.8 4.6 4.4 4.2 242.6440 4 3.8 3.6 3.4 3.2 3 2.8 2.6 2.4 2.2 2 1.8 1.6 1.4 1.2 243.1456 1 0.8 242.1454 0.6 0.4 0.2 243.6465 0 242 242.2 242.4 242.6 242.8 243 243.2 243.4 243.6 243.8 244 244.2 244.4 Counts vs. Mass-to-Charge (m/z) Figure S58. HR-MS Spectrum (experimental bottom, and theoretical top right) of [2b(H)(BH2. NMe3)][BAr Cl 4] 2 40

Reactions of [2a][BAr Cl 4]2 with R3SiH (R = Et, Ph): Figure S59. 31 P NMR Spectrum of the reaction mixture between in situ formed [2a][BAr Cl 4] 2 and Et 3SiH 41

Figure S60. 31 P{ 1 H} NMR Spectrum of the reaction mixture between in situ formed [2a][BAr Cl 4] 2 and Et 3SiH 42

[{C6H4(MeN)2C}2C. P(N i Pr2)H][BAr Cl 4], [2a-H][BAr Cl 4]: Figure S61. 31 P NMR Spectrum of the reaction mixture between in situ formed [2a][BAr Cl 4] 2 and n Bu 3SnH 43

Figure S62. 31 P{ 1 H} NMR Spectrum of the reaction mixture between in situ formed [2a][BAr Cl 4] 2 and nbu 3SnH 44

Reaction of [2a][BAr Cl 4]2 with H2O. When [2a][BAr Cl 4]2 reacted with silanes and stannane (Figures S59-62), apart from the formation of [2a-H][BAr Cl 4], a new signal at P 12 ppm with coupling constant value of 1 JP-H = 560 Hz was observed in the 31 P/ 31 P{ 1 H} NMR spectrum. The following peak resembles the compound [{C6H4(MeN)2C}2C. P(O)(H)N i Pr2][BAr Cl 4], [2a(O)(H)][BAr Cl 4] derived from slight hydrolysis (less than 10% in abundance) of [2a][BAr Cl 4]2. The product of hydrolysis was synthesized independently according to the following procedure: 256 mg (0.40 mmol, 2 equiv) of Na[BAr Cl 4] was added to the solution of 100 mg (0.19 mmol, 1 equiv) of [2a- Cl]Cl in 40 ml of 1,2-difluorobenzene, and the resulting mixture was stirred for 5 minutes at ambient temperature. Then, 4 μl (0.19 mmol, 1 equiv) of H2O was added followed by additional 2 hours of stirring at ambient temperature. NaCl was removed by filtration, and the resulting solution treated with n-pentane (around 100 ml) to give [2a(O)(H)][BAr Cl 4] as a light yellow solid that was isolated by filtration and dried under vacuum. Yield: 186 mg (93%). 1 H NMR (400 MHz, CD2Cl2, 298 K): 0.90 (br s, 6H, (CH3)2CH), 1.39 (br s, 6H, (CH3)2CH), 3.42 (br s, 12H, NCH3), 3.78 (br m, 2H, CH(CH3)2), 6.89 (t, 4 JHH = 2 Hz, 8H, p-h, BAr Cl 4), 7.03 (m, 16H, BAr Cl 4), 7.31 (br s, 4H), 8.13 (d, 1 JHP = 560 Hz, PH), 7.57 (m, 4H). 13 C{ 1 H} NMR (100 MHz, CD2Cl2, 298 K): 23.0 (s, (CH3)2CH), 23.6 (s, (CH3)2CH), 32.9 (br s, NCH3), 47.2 (s, CH(CH3)2), 111.8 (s, CH arom.), 122.9 (s, p-c, BAr Cl 4), 127.6 (s, CH arom.), 131.2 (s, CH arom.), 132.9 (br s, o-c, BAr Cl 4), 133.0 (s, m-c, BAr Cl 4), 150.4 (br s, NCN), 164.7 (q, 1 JCB = 49 Hz, ipso-c, BAr Cl 4). 31 P NMR (160 MHz, CD2Cl2, 298 K): δ 12.3 (d, 1 JPH = 560 Hz). 31 P{ 1 H} NMR (160 MHz, CD2Cl2, 298 K): δ 12.9 (s). HR- MS Calculated for [C25H35N5OP] + [2a(O)(H)] + : m/z 452.2574. Found: 452.2576. 45

Figure S63. 1 H NMR Spectrum of [2a(O)(H)][BAr Cl 4] Figure S64. 13 C{ 1 H} NMR Spectrum of [2a(O)(H)][BAr Cl 4] 46

Figure S65. 31 P NMR Spectrum of [2a(O)(H)][BAr Cl 4] Figure S66. 31 P{ 1 H} NMR Spectrum of [2a(O)(H)][BAr Cl 4] 47

x10 7 +ESI Scan (rt: 0.123 min) Frag=100.0V Sept23-2016 ND8.d 1.2 1.15 1.1 1.05 452.2576 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 453.2607 0.25 0.2 0.15 0.1 0.05 0 454.2653 455.2679 452 452.5 453 453.5 454 454.5 455 455.5 Counts vs. Mass-to-Charge (m/z) Figure S67. HR-MS Spectrum (experimental bottom, and theoretical top right) of [2a(O)(H)][BAr Cl 4] 48

[{C6H4(MeN)2C}2C. P(Ph)H][X], [2b-H][X], [X] = [AlCl4] and [BAr Cl 4]: Figure S68. 1 H NMR Spectrum of [2b-H][BAr Cl 4] Figure S69. 13 C{ 1 H} NMR Spectrum of [2b-H][BAr Cl 4] 49

Figure S70. 31 P NMR Spectrum of [2b-H][BAr Cl 4] Figure S71. 31 P{ 1 H} NMR Spectrum of [2b-H][BAr Cl 4] 50

x10 4 +ESI Scan (rt: 0.768 min) Frag=50.0V Sept30-2016 ND2.d 1.7 1.6 1.5 413.1892 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 414.1920 0.3 0.2 0.1 0 413 413.2 413.4 413.6 413.8 414 414.2 414.4 414.6 414.8 415 415.2 415.4 415.6 Counts vs. Mass-to-Charge (m/z) Figure S72. HR-MS Spectrum (experimental bottom, and theoretic top right) of [2b-H][BAr Cl 4] 51

Reaction of [2b][BAr Cl 4]2 with 1,3,5-cycloheptatriene: Figure S73. 31 P NMR Spectrum of the reaction between in situ formed [2b][BAr Cl 4] 2 and cycloheptatriene 52

Figure S74. 31 P{ 1 H} NMR Spectrum of the reaction between in situ formed [2b][BAr Cl 4] 2 and cycloheptatriene 53

[{C6H4(MeN)2C}2C. P{(CH)6CH2}Ph][BAr Cl 4]2, [2b{(CH)6CH2}][BAr Cl 4]2: Figure S75. 1 H NMR Spectrum of [2b{(CH)6CH2}][BAr Cl 4] 2 54

Figure S76. 13 C{ 1 H} NMR Spectrum of [2b{(CH)6CH2}][BAr Cl 4] 2 Figure S77. 31 P NMR Spectrum of [2b{(CH)6CH2}][BAr Cl 4] 2 55

x10 6 +ESI Scan (rt: 1.300 min) Frag=100.0V Sept23-2016 ND4.d 2 1.9 1.8 252.1218 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 252.6244 0.5 0.4 0.3 0.2 0.1 0 253.1264 253.6289 252 252.2 252.4 252.6 252.8 253 253.2 253.4 253.6 253.8 Counts vs. Mass-to-Charge (m/z) Figure S78 HR-MS Spectrum (experimental bottom, and theoretical top right) of [2b{(CH)6CH2}][BAr Cl 4] 2 56

Reaction of [2b-H][BAr Cl 4] with tropylium tetrafluoroborate ([C7H7][BF4]): Figure S79. 31 P NMR Spectrum of the reaction mixture between [2b][BAr Cl 4] 2 and [C 7H 7][BF 4] 57

Figure S80. 31 P{ 1 H} NMR Spectrum of the reaction mixture between [2b][BAr Cl 4] 2 and [C 7H 7][BF 4] 58

[{C6H4(MeN)2C}2C. P(H)(CH{C6H4}2O)Ph][BAr Cl 4]2, [2b(H)(CH{C6H4}2O)][BAr Cl 4]2: Figure S81. 1 H NMR Spectrum of [2b(H)(CH{C6H4}2O)][BAr Cl 4] 2 59

Figure S82. 1 H NMR Spectra of [2b(H)(CH{C6H4}2O)][BAr Cl 4] 2 recorded using different effective frequencies 300 (top), 400 (middle), and 500 (bottom) MHz Figure S83. 13 C{ 1 H} NMR Spectrum of [2b(H)(CH{C6H4}2O)][BAr Cl 4] 2 60

Figure S84. 31 P{ 1 H} NMR Spectrum of [2b(H)(CH{C6H4}2O)][BAr Cl 4] 2 Figure S85. 31 P NMR Spectrum of [2b(H)(CH{C6H4}2O)][BAr Cl 4] 2 61

x10 5 +ESI Scan (rt: 0.387 min) Frag=50.0V Sept30-2016 ND2.d 1.35 1.3 1.25 1.2 1.15 1.1 1.05 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 593.2469 594.2502 595.2523 593 593.5 594 594.5 595 595.5 596 596.5 Counts vs. Mass-to-Charge (m/z) Figure S86. HR-MS Spectrum (experimental bottom, and theoretical top right) of [2b(CH{C6H4}2O)] + 62

x10 6 +ESI Scan (rt: 3.785 min) Frag=175.0V Sept23-2016 ND5.d 1.2 1.15 1.1 1.05 181.0653 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 182.0692 0.1 0.05 0 180.8 181 181.2 181.4 181.6 181.8 182 182.2 182.4 182.6 182.8 183 183.2 183.4 Counts vs. Mass-to-Charge (m/z) Figure S87. HR-MS Spectrum (experimental bottom, and theoretical top right) of [CH{C6H4}2O] + 63

2. Crystallographic Data Crystallographic data for [1][BAr Cl 4]: C36H40BCl8N2P, M r 826.08, monoclinic, P 1 21/n 1, a = 9.7448(3) Å, b = 13.9148(4) Å, and c = 29.7605(8) Å, α = 90, β = 95.6699(14), and γ = 90, V = 4015.7(2) Å 3, Z = 4, ρ = 1.366 c gcm-3, T = 103(2) K, λ = 0.71073 Å; 116505 reflections collected, 15393 independent [Rint = 0.0294], which were used in all calculations; R1 = 0.0348, wr2 = 0.0848 for I > 2σ(I), and R1 = 0.0414, wr2 = 0.0881 for all unique reflections; max and min residual electron densities 1.439 eå -3 and -0.672 eå -3. CCDC 1544307. Crystallographic data for [2a-Cl][SbF6]: C52H72Cl6F12N10P2Sb2, M r 1583.33, triclinic, P - 1, a = 9.9510(2) Å, b = 18.1607(5) Å, and c = 19.4532(4) Å, α = 70.4829(11), β = 88.0745(12), and γ = 82.4796(14), V = 3284.82(13) Å 3, Z = 2, ρ = 1.601 c gcm-3, T = 153(2) K, λ = 0.71073 Å; 68666 reflections collected, 14331 independent [Rint = 0.0584], which were used in all calculations; R1 = 0.0464, wr2 = 0.1195 for I > 2σ(I), and R1 = 0.0674, wr2 = 0.1505 for all unique reflections; max and min residual electron densities 2.532 eå -3 and -1.971 eå -3. CCDC 1544302. Crystallographic data for [2b-Cl][SbF6]: C53H56Cl8F12N8P2Sb2, M r 1622.09, triclinic, P -1, a = 8.5429(8) Å, b = 15.9590(15) Å, and c = 24.892(2) Å, α = 107.4440(19), β = 98.8580(19), and γ = 91.986(2), V = 3187.2(5) Å 3, Z = 2, ρ = 1.690 c gcm-3, T = 103(2) K, λ = 0.71073 Å; 40964 reflections collected, 17232 independent [Rint = 0.0566], which were used in all calculations; R1 = 0.0659, wr2 = 0.1553 for I > 2σ(I), and R1 = 0.1066, wr2 = 0.1793 for all unique reflections; max and min residual electron densities 2.859 eå - 3 and -2.259 eå -3. CCDC 1544299. Crystallographic data for [2b][BAr Cl 4]2: C85H57B2Cl16F4N4P, M r 1830.13, triclinic, P -1, a = 13.4121(11) Å, b = 13.9406(12) Å, and c = 22.8317(19) Å, α = 84.027(3), β = 82.751(3), and γ = 76.978(3), V = 4113.2(6) Å 3, Z = 2, ρ = 1.478 c gcm-3, T = 103(2) K, λ = 0.71073 Å; 77999 reflections collected, 19869 independent [Rint = 0.1461], which were used in all calculations; R1 = 0.0705, wr2 = 0.1609 for I > 2σ(I), and R1 = 0.1707, wr2 = 0.2483 for all unique reflections; max and min residual electron densities 0.676 eå -3 and -0.533 eå -3. CCDC 1544303. Crystallographic data for [2b(CH2CCH3)2][AlCl4]2: C32H37Al2Cl10N4P, M r 917.08, monoclinic, P 1 21/n 1, a = 9.5886(4) Å, b = 36.6578(17) Å, and c = 12.1022(7) Å, α = 90, β = 98.046(3), and γ = 90, V = 4212.0(4) Å 3, Z = 4, ρ c = 1.446 gcm-3, T = 153(2) K, λ = 0.71073 Å; 44804 reflections collected, 8081 independent [Rint = 0.1497], which were used in all calculations; R1 = 0.0607, wr2 = 0.1619 for I > 2σ(I), and R1 = 0.1615, wr2 = 0.2401 for all unique reflections; max and min residual electron densities 0.558 eå -3 and -0.665 eå -3. CCDC 1544300. Crystallographic data for [1(H)(BH2. Py)][BAr Cl 4]: C41H48B2Cl8N3P, M r 919.01, monoclinic, P 1 21/c 1, a = 14.6575(6) Å, b = 13.5987(5) Å, and c = 23.7606(9) Å, α = 64

90, β = 106.9035(14), and γ = 90, V = 4531.4(3) Å 3, Z = 4, ρ c = 1.347 gcm-3, T = 103(2) K, λ = 0.71073 Å; 71364 reflections collected, 14451 independent [Rint = 0.1219], which were used in all calculations; R1 = 0.0547, wr2 = 0.1285 for I > 2σ(I), and R1 = 0.0870, wr2 = 0.1492 for all unique reflections; max and min residual electron densities 0.914 eå - 3 and -0.690 eå -3. CCDC 1544301. Crystallographic data for [1(H)(BH2. NMe3)][BAr Cl 4]: C39H52B2Cl8N3P, M r 899.02, triclinic, P -1, a = 12.7943(5) Å, b = 12.8697(5) Å, and c = 15.7309(6) Å, α = 96.1461(14), β = 109.8769(14), and γ = 108.7461(14), V = 2237.60(15) Å 3, Z = 2, ρ c = 1.334 gcm-3, T = 153(2) K, λ = 0.71073 Å; 105482 reflections collected, 17242 independent [Rint = 0.1075], which were used in all calculations; R1 = 0.0511, wr2 = 0.1189 for I > 2σ(I), and R1 = 0.0823, wr2 = 0.1390 for all unique reflections; max and min residual electron densities 1.402 eå -3 and -0.594 eå -3. CCDC 1544308. Crystallographic data for [2b(H)(BH2. NMe3)][AlCl4]2: C28H37Al2BCl8N5P, M r 822.96, triclinic, P -1, a = 11.0690(7) Å, b = 18.5787(13) Å, and c = 19.7880(13) Å, α = 90.450(3), β = 105.030(3), and γ = 90.613(3), V = 3929.7(5) Å 3, Z = 4, ρ c = 1.391 gcm-3, T = 153(2) K, λ = 0.71073 Å; 130301 reflections collected, 16208 independent [Rint = 0.0625], which were used in all calculations; R1 = 0.0703, wr2 = 0.2133 for I > 2σ(I), and R1 = 0.0951, wr2 = 0.2356 for all unique reflections; max and min residual electron densities 0.907 eå - 3 and -0.933 eå -3. CCDC 1544309. Crystallographic data for [2. PH2][AlCl4]: C19H22AlCl4N4P, M r 506.15, monoclinic, P 1 21/n 1, a = 10.4946(9) Å, b = 14.2035(15) Å, and c = 16.6481(15) Å, α = 90, β = 100.966(3), and γ = 90, V = 2436.3(4) Å 3, Z = 4, ρ = 1.380 c gcm-3, T = 103(2) K, λ = 0.71073 Å; 30724 reflections collected, 5364 independent [Rint = 0.0694], which were used in all calculations; R1 = 0.0581, wr2 = 0.1656 for I > 2σ(I), and R1 = 0.0911, wr2 = 0.1842 for all unique reflections; max and min residual electron densities 1.012 eå -3 and - 0.727 eå -3. CCDC 1544305. Crystallographic data for [2b-H][AlCl4]: C50H53Al2Cl8N8P2, M r 1165.50, orthorhombic, P c a 21, a = 21.0177(16) Å, b = 22.3251(16) Å, and c = 11.6657(9) Å, α = 90, β = 90, and γ = 90, V = 5473.8(7) Å 3, Z = 4, ρ = 1.414 c gcm-3, T = 103(2) K, λ = 0.71073 Å; 10242 reflections collected, 10242 independent [Rint = 0.1152], which were used in all calculations; R1 = 0.0561, wr2 = 0.1276 for I > 2σ(I), and R1 = 0.1080, wr2 = 0.1637 for all unique reflections; max and min residual electron densities 0.747 eå -3 and -0.523 eå -3. CCDC 1544304. Crystallographic data for [2b{(CH)6CH2}][BAr Cl 4]2: C92H67B2Cl16F4N4P, M r 1924.28, triclinic, P -1, a = 13.3965(11) Å, b = 13.4151(12) Å, and c = 25.380(2) Å, α = 93.476(5), β = 101.749(5), and γ = 101.070(5), V = 4358.9(7) Å 3, Z = 2, ρ c = 1.466 gcm -3, T = 153(2) K, λ = 0.71073 Å; 72340 reflections collected, 17104 independent [Rint = 0.0978], which were used in all calculations; R1 = 0.0997, wr2 = 0.2567 for I > 2σ(I), 65

and R1 = 0.1240, wr2 = 0.2787 for all unique reflections; max and min residual electron densities 0.892 eå -3 and -0.816 eå -3. CCDC 1544306. 2.1. Crystal structures Figure S88. Molecular view of [1][BAr Cl 4]2 set at 50% probability. Counterion and hydrogen atoms were omitted for clarity. Selected bond lengths [Å] and angle [ ]: N1-P1, 1.6183(10), N2-P1, 1.6252(10), N1-P1-N2, 110.65(5). 66

Figure S89. Molecular view of [2b{(CH)6CH2}][BAr Cl 4]2 set at 50% probability. Counterions and hydrogen atoms were omitted for clarity. Selected bond lengths [Å] and angles [ ]: P1-C1, 1.674(16), P1-C2, 1.796(10), C1-P1-C2, 107.2(8). 67

3. Cartesian Coordinates for Phosphenium Cations [1] + 15-0.045857 0.120836-0.005997 1-2.522489-2.065630 2.630725 7 0.048458 0.030173 1.636675 1 1.718381 1.940719 3.947248 7 1.436858 0.052529-0.721810 1 0.524231 2.468424 2.749360 6 1.235502 2.062371-2.229411 1 0.037312 1.438466 4.113988 6 2.714138-0.555255-0.213263 1 2.517209-0.496266 3.994201 6 1.187078 0.394460 2.547927 1 0.863767-1.094854 4.123415 1-2.082020 1.688779 2.202163 1 1.904556-1.661010 2.806325 6-1.264531-0.334716 2.319259 1 2.476159 0.341009-2.497845 6-1.653522-1.787769 2.025626 1 2.492767-0.909189 0.792966 6-2.388734 0.658742 1.997624 1 4.733093-0.002188 0.308470 6 1.637548-0.789074 3.412259 1 4.147949 0.822112-1.136188 6 0.830240 1.632687 3.385905 1 3.585100 1.340064 0.461761 6 1.458861 0.547577-2.163136 1 3.950020-2.279721-0.574048 6 0.497814-0.235608-3.067153 1 2.265085-2.517110-1.068091 6 3.853800 0.467970-0.143194 1 3.370055-1.549488-2.069531 6 3.086857-1.795103-1.041892 1 1.388564 2.412464-3.255307 1-1.040457-0.253370 3.383573 1 0.212417 2.329207-1.938325 1 2.006921 0.688084 1.893394 1 1.933522 2.599331-1.579797 1-2.715762 0.591374 0.954701 1 0.664437 0.062047-4.107250 1-3.255782 0.431666 2.625962 1 0.667686-1.313708-2.991477 1-1.927062-1.923909 0.972406 1-0.551973-0.029337-2.833608 1-0.838333-2.477313 2.265523 [2a] + 6 2.923327 3.430617-1.041238 1-6.999017 1.086153-0.963303 6 1.985020 2.553145-0.490278 1-4.809446 1.925932-1.764090 6 1.330230 2.835713 0.717786 1-2.357372-3.062008 1.174134 6 1.575650 4.012388 1.430699 1-2.859333-1.902214 2.432061 6 2.506847 4.886903 0.881336 1-1.162805-1.958868 1.904563 6 3.168266 4.601376-0.332118 1-1.604517 2.529635-1.411019 7 1.496909 1.322706-0.932703 1-2.632532 1.721074-2.617445 6 0.597976 0.842899-0.028954 1-0.983774 1.141913-2.357396 7 0.487088 1.754639 0.975481 1 3.440988 3.216725-1.969934 6-0.168950-0.390350-0.158442 1 3.888532 5.313790-0.720671 15 0.329592-2.020314-0.555833 1 2.731506 5.813536 1.399206 7 1.869973-2.453088-0.115683 1 1.069699 4.241384 2.362261 6 2.237979-3.801077-0.733929 1 2.863562 0.262148-2.139669 6 3.555611-3.719323-1.510460 1 1.900448 1.510884-2.971651 6-0.341618 1.643405 2.176576 1 1.142873-0.027525-2.496603 6 1.877062 0.725965-2.212492 1-1.222424 2.286659 2.094576 6-1.629999-0.269491-0.146862 1 0.249418 1.949373 3.042364 7-2.364627 0.625884-0.867220 1-0.651158 0.608096 2.308869 6-3.721251 0.432556-0.606911 1 3.472800-2.810133 1.113402 6-3.807158-0.643427 0.288042 1 1.443118-4.007102-1.459986 7-2.500036-1.042018 0.566114 1 4.584683-0.705446 1.135777 6-4.862454 1.087125-1.078808 1 4.223191-1.084514-0.549038 6-6.085713 0.610548-0.621272 1 3.262139 0.131100 0.330944 6-6.172028-0.475456 0.275884 1 2.909466-1.366231 2.985701 6-5.037107-1.124186 0.747477 1 1.513339-0.699828 2.139624 6-1.857650 1.567570-1.865567 1 1.543645-2.420596 2.599970 6-2.196856-2.059550 1.577709 1 2.354684-5.881427-0.207416 68

6 2.840970-1.943083 0.912976 1 3.021744-4.841465 1.045322 6 2.148238-1.586082 2.230730 1 1.259171-4.962585 0.834445 6 3.771650-0.831310 0.413502 1 3.720382-4.672199-2.022826 6 2.217955-4.925054 0.307247 1 3.527185-2.931534-2.269813 1-5.112083-1.963501 1.430028 1 4.416508-3.550795-0.855891 1-7.149625-0.813512 0.603279 [2b] + 7 0.571818 1.473841 0.962420 6-2.320802-2.170670 1.658561 6 0.639074 0.541125-0.024929 6-1.786365 1.350088-1.878516 7 1.605809 0.917930-0.901852 1-5.224877-1.874736 1.546741 6 2.184303 2.108148-0.461275 1-7.194416-0.644291 0.676072 6 1.518386 2.469127 0.720252 1-6.942079 1.181337-0.963542 6 1.846543 3.630179 1.426591 1-4.711127 1.862440-1.801757 6 2.869776 4.407527 0.897019 1-2.503327-3.166531 1.248694 6 3.541640 4.043840-0.290725 1-2.998180-1.988232 2.495254 6 3.214716 2.890032-0.992953 1-1.292695-2.107828 2.012537 6-0.206517-0.653641-0.128273 1-1.530319 2.327457-1.459928 15 0.293158-2.293378-0.358517 1-2.535275 1.480169-2.660803 6 2.053958-2.459462-0.071057 1-0.906192 0.887780-2.323283 6 2.878110-1.659746 0.757733 1 3.741409 2.615478-1.900228 6 4.209315-2.000078 0.953569 1 4.336137 4.682057-0.663258 6 4.749671-3.132063 0.323396 1 3.160187 5.319072 1.408964 6 3.949139-3.940049-0.487253 1 1.332753 3.920225 2.336568 6 2.606847-3.620269-0.670123 1 2.923665-0.330158-1.972057 6 2.008774 0.243895-2.137946 1 2.180610 1.000843-2.905563 6-0.286179 1.441234 2.149629 1 1.216344-0.427177-2.467723 6-1.662577-0.446373-0.103631 1-1.141001 2.111907 2.025420 7-2.566648-1.143098 0.638514 1 0.300573 1.760607 3.013102 6-3.849112-0.676383 0.352874 1-0.632960 0.423567 2.322044 6-3.706242 0.357769-0.584385 1 2.470112-0.800690 1.280616 7-2.342261 0.466305-0.851066 1 4.831935-1.397781 1.608087 6-4.809849 1.056380-1.083099 1 5.791949-3.390797 0.484264 6-6.055574 0.668885-0.604632 1 4.364668-4.824202-0.959924 6-6.199958-0.374642 0.336150 1 1.981368-4.268831-1.279005 6-5.103352-1.067498 0.833081 69