Combined Spectroscopic and Quantum Chemical Study of [trans-ru(c CC 6 H 4 R 1 -

Transcript

1 Combined Spectroscopic and Quantum Chemical Study of [trans-ru(c CC 6 H 4 R 1-4) 2 (dppe) 2 ] n+ and [trans-ru(c CC 6 H 4 R 1-4)(C CC 6 H 4 R 2-4)(dppe) 2 ] n+ (n = 0, 1) Complexes: Interpretations Beyond the Lowest Energy Conformer Paradigm. Santiago Marqués-González, Matthias Parthey, Dmitry S. Yufit, Judith A.K. Howard, Martin Kaupp,*, Paul J. Low *,, Department of Chemistry, Durham University, South Rd, DH1 3LE, Durham (UK) Technische Universität Berlin, Institut für Chemie Sekr. C7, Strasse des 17. Juni 135, Berlin (Germany) New permanent address: School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, 6009, Perth (Australia) 1

2 LIGAND SYNTHESIS All reactions were carried out in flame-dried glassware under an oxygen-free nitrogen atmosphere using standard Schlenk techniques. Triethylamine was purified by distillation from CaSO 4, other reaction solvents were purified and dried using Innovative Technology SPS-400 and degassed before use. The catalyst Pd(PPh 3 ) 4 was prepared by literature methods. 1 Other reagents were purchased commercially and used as received. NMR spectra were recorded in deuterated solvent solutions on Bruker DRX-400 and Varian Inova 300, 400, 500 spectrometers and referenced against solvent resonances ( 1 H, 13 C). ESI mass spectra were recorded using a TQD mass spectrometer (Waters Ltd, UK). Samples were (1 mg/ml) in analytical grade methanol. ASAP mass spectra were recorded from solid aliquots on an LCT Premier XE mass spectrometer (Waters Ltd, UK) or Xevo QToF mass spectrometer (Waters Ltd, UK) in which the aliquot is vaporized using hot N 2, ionized by a corona discharge and carried to the TOF detector (working range m/z). Matrix assisted- Laser Desorption/Ionisation (MALDI) mass spectra was obtained using an Autoflex II TOF/TOF mass spectrometer (Bruker Daltonik GmBH) using a trans-2-[3-(4-tertbutylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB) matrix. Infrared spectra were recorded from CH 2 Cl 2 solutions and nujol mulls on CaF 2 plates. Preparation of 4-bromo-(trimethylsilylethynyl)benzene. 2 To a 500 ml round Schlenk flask charged with NEt 3 (250 ml) immersed in ice, 4-iodo-bromobenzene (18.05 g, mmol), Pd(PPh 3 ) 4 (1.85 g, 1.60 mmol) and CuI ( 0.30 g, 1.6 mmol) were added. To the cooled solution trimethylsilylacetylene (11.0 ml, 7.51 g, 76.5 mmol) was added drop wise. The mixture was stirred in an ice bath for 8 h. Upon completion of the reaction the brown suspension was taken to dryness under reduced pressure and the residue was purified by silica gel column chromatography (hexane). Removal of solvent from the main fraction yielded a colourless oil that crystallized on standing. Yield 15.9 g, 62.8 mmol, 99%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.43 (d, J = 9 Hz, 2H, c), 7.32 (d, J = 9 Hz, 2H, b), 0.24 (s, 9H, g). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ 133.5, (b/c), 122.9, (a/d), (f), 95.7 (e), 0.0 (g). MS + (ASAP) m/z (%): (100, [2M-2H] + ); (41.8, [M] + ). IR (nujol) cm -1 : 2159 (s) ν(c C). 2

3 Preparation of ((4-(3,3-dimethylbut-1-yn-yl)phenyl)ethynyl)trimethylsilane. To a 100 ml oven-dried Schlenk flask charged with ((4-bromophenyl)ethynyl)trimethylsilane (2.53 g, 9.99 mmol), Pd(PPh 3 ) 4 (0.60 g, 0.52 mmol) and CuI ( 0.30 g, 0.52 mmol) in NEt 3 (100 ml), 3,3-dimethylbut-1-yne (1.53 ml, 1.02 g, 12.4 mmol) was added. The mixture was stirred at reflux overnight. The brown suspension was filtered and the red filtrate taken to dryness under reduced pressure. The residue was purified through a silica gel column using hexane as eluent. The pure product was obtained as an off-white powder upon solvent evaporation of the main fraction. Yield 2.16 g, 8.49 mmol, 85.4%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.37 (d, J = 9 Hz, 2H, g), 7.31 (d, J = 9 Hz, 2H, f), 1.32 (s, 9H, a), 0.25 (s, 9H, k). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ 133.8, (e/h), 122.4, (i/j), 105.0, 100.7, 95.6 (d/i/j), 79.0 (c), 31.1 (a), 28.2 (b) 0.1 (k). Preparation of 1-(3,3-dimethylbut-1-yn-1-yl)-4-ethynylbenzene. To a 250 ml round bottomed flask charged with a solution of methyl ((4-(3,3-dimethylbut-1-yn-1- yl)phenyl)ethynyl)trimethylsilane (1.5 g, 5.9 mmol) in MeOH/THF (1:1) (100 ml), K 2 CO 3 (0.83 g, 6.0 mmol) and the suspension was stirred at room temperature overnight. The solution was then filtered and the filtrate taken to dryness under reduced pressure. The resultant black oil was re-dissolved in Et 2 O (50 ml) and washed with water (2 50 ml) and brine (1 50 ml) and dried over MgSO 4. Removal of solvent yielded the pure product as a yellowish oil. Yield 1.0 g, 5.5 mmol, 93%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.39 (d, J = 9 Hz, 2H, g), 7.56 (d, J = 9 Hz, 2H, f), 3.13 (s, 1H, k), 1.31 (s, 9H, a). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ 132.0, (f/g), 124.9, (e/h), 100.9, 83.6, 78.9, 78.4 (c/d/i/j), 31.1 (a), 28.2 (b). IR (cast) cm -1 : 3291 (m) ν(c C-H); 2236 (m); 2192 (w) ν(c C). Preparation of 2-methyl-4-(4-((trimethylsilyl)ethynyl)phenyl)but-3-yn-2-ol. 3 To a 500 ml Schlenk flask immersed in an ice bath and charged with NEt 3 (450 ml), 1-bromo-4- iodobenzene (30.01 g, mmol), Pd(PPh 3 ) 4 (6.12 g, 5.30 mmol) and CuI (1.01 g, 5.30 mmol) were added. To the cooled suspension, trimethylsilylacetylene (16.5 ml, 11.4 g, 116 3

4 mmol) was added in small portions over an hour. After stirring the solution at 0 ºC for 6 h, trimethylsilylacetylene excess was removed under reduced pressure keeping the reaction vessel in the ice bath. After refilling the vessel with N 2, 2-methyl-3-butyn-2-ol (11.3 ml, 9.81 g, 116 mmol) was added and the reaction mixture was taken out of the ice bath and heated at reflux overnight. The reaction mixture was then taken to dryness under reduced pressure, and the resulting black residue was re-dissolved in CH 2 Cl 2 and adsorbed onto silica for further silica gel column chromatography (hexane). The pure product was collected upon solvent evaporation of the main fraction as a yellow powder. Yield 21 g, 83 mmol, 78 %. 1 H NMR (400 MHz, CDCl 3 ) δ 7.37 (d, J = 9 Hz, 2H, e), 7.31 (d, J = 9 Hz, 2H, f), 1.32 (s, 6H, k), 2.01 (s, 1H, l), 0.25 (s, 9H, a). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ 131.8, (e/f), 123.0, (d/g), (b), 96.2, 95.8, 81.8 (c/h/i), 65.7 (j), (k), 0.0 (a). MS + (ASAP) (m/z) (100, [M-OH] + ). Preparation of 1-ethynyl-4-(trimethylsilylethynyl)benzene. 3 A 250 ml round bottom flask, fitted with a nitrogen purge, reflux condenser and bubbler was charged with sodium hydroxide (0.63 g, 0.16 mmol), 2-methyl-4-(4-((trimethylsilyl)ethynyl) phenyl)but-3- yn-2-ol (3.25 g, 12.6 mmol) and anhydrous toluene (150 ml). The solution was heated at reflux for 30 min whilst nitrogen was bubbled through it. Upon completion of the reaction, the red solution was poured into water, and the organic phase was washed with water (2 150 ml) and brine (1 150 ml), and dried over MgSO 4. The solvent was removed under reduced pressure and the residue was purified by silica gel column chromatography using hexane:ch 2 Cl 2 (9:1) as the eluent. Removal of solvent from the main fraction yielded the pure product as a white solid. Yield 1.83 g, 9.23 mmol, 73%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.41 (s, 4H, e/f), 3.16 (s, 1H, j), 0.25 (s, 9H, a). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ 132.1, (e/f), 123.7, (d/g), (b), 96.6 (c), 83.3 (h), 79.1 (i), 0.0 (a). MS-ASAP + (m/z) (100, [M-CH 3 ] + ), (24.4, [M] + ). IR (nujol) cm -1 : 3311 (s) ν(c C-H); 2159 (s) ν(c C). Preparation of methyl 4-((trimethylsilyl)ethynyl)benzoate. 4 To a 250 ml Schlenk flask charged with methyl 4-iodobenzoate (10.2 g, 38.9 mmol), Pd(PPh 3 ) 4 (2.24 g, 1.94 mmol) and CuI ( g, 1.94 mmol) and NEt 3 (200 ml), trimethylsilylacetylene (7.0 ml, 4

5 4.8 g, 48.9 mmol) was added. The mixture was stirred at room temperature overnight. The mixture was taken to dryness under reduced pressure and the residue was purified through a silica gel column using hexane:ch 2 Cl 2 (8:2) as the eluent. Removal of solvent from the main fraction yielded an off-white powder. Yield 8.01 g, 34.5 mmol, 89%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.89 (d, J = 9 Hz, 2H, f), 7.47 (d, J = 9 Hz, 2H, e), 3.85 (s, 3H, i), 0.20 (s, 9H, a). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ (h), 132.0, (e/f), (g), (d), 104.2, 97.8 (b/c), 52.4 (i), 0.0 (a). MS + (ASAP) (m/z) (100, [2M] + ), (70, [M+H] + ). IR (nujol) cm -1 : 2162 (m) ν(c C); 1732 (s) ν(c=o). Preparation of methyl-4-ethynylbenzoate. 5 To a solution of methyl 4- ((trimethylsilyl)ethynyl)benzoate (8.10 g, 34.9 mmol) in THF (150 ml), tetra-nbutylammonium fluoride (TBAF) (1 M in THF, 35.0 ml, 35.0 mmol) was added yielding an orange solution that was stirred at room temperature overnight. The solution was then taken to dryness under reduced pressure and the resultant black oil was purified through a silica gel column using hexane:ch 2 Cl 2 (1:1) as the eluent. Removal of solvent from the main fraction yielded the pure product as a yellowish powder. Yield 4.77 g, 29.8 mmol, 85.4%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.99 (d, J = 9 Hz, 2H, f), 7.56 (d, J = 9 Hz, 2H, e), 3.92 (s, 3H, i), 3.23 (s, 1H, a). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ (h), 132.2, (e/f), (g), (d), 82.9, 80.2 (b/c), 52.4 (i). MS + (ASAP) (m/z) (68, [2M] + ), (27, [M+H] + ). IR (nujol) cm -1 : 3244 (s) (C sp H); 2104 (w) ν(c C); 1700 (s) ν(c=o). Preparation of 4-(trimethylsilylethynyl)aniline. 6 In a 100 ml Schlenk flask 4- iodoaniline (4.2 g, 20 mmol), trimethylsilylacetylene (3.5 ml, 2.4 g, 25 mmol), Pd(PPh 3 ) 4 (1.184 g, mmol) and CuI (0.239 g, mmol) were dissolved in anhydrous degassed NEt 3 (100 ml). The resulting solution was heated at reflux temperature overnight. Upon completion of the reaction, the black mixture was taken to dryness under reduced pressure and the residue was purified by silica gel column chromatography (hexane:ch 2 Cl 2 ) (1:1). Removal of solvent from the main fraction yielded a colourless oil that crystallized on standing. Yield 2.2 g, 12 mmol, 60%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.27 (d, J = 9 Hz, 2H, e), 6.57 (d, J = 9 Hz, 2H, f), 3.79 (s br., 2H, h), 0.22 (s, 9H, a). 5

6 Preparation of 4-ethynylaniline. 6 To a solution of 4-(trimethylsilylethynyl) aniline (2.12 g, 11.2 mmol) in THF (50 ml), TBAF (1M in THF, 12 ml ~12 mmol) was added and the resulting black solution stirred at room temperature overnight. The solution was then taken to dryness under reduced pressure and the remaining black oil was re-dissolved in CH 2 Cl 2 (50 ml). The organic phase was washed with water (2 50 ml), brine (1 50 ml) and dried over MgSO 4. Removal of solvent of the organic phase yielded the pure product as a light-brown solid. Yield 1.3 g, 11.1 mmol, 99%. 1 H NMR (400 MHz, CDCl 3 ) δ 7.29 (d, J = 9 Hz, 2H, e), 6.59 (d, J = 9 Hz, 2H, f), 3.82 (s, 2H, h), 2.95 (s, 1H, a). IR (nujol) cm -1 : 3485, 3388 (m) ν(nh 2 ); 3259 (m) ν(c C-H); 2097 (w) ν(c C). 6

7 NMR DATA (2d) trans-rucl(c CC 6 H 4 CO 2 Me-4)(dppe) 2 : 7

8 (2e) trans-rucl(c CC 6 H 4 NO 2-4)(dppe) 2 : 8

9 (2f) trans-rucl(c CC 6 H 4 C CSiMe 3-4)(dppe) 2 : 9

10 (2g) trans-rucl(c CC 6 H 4 C CCMe 3-4)(dppe) 2 : 10

11 (2i) trans-rucl(c CC 6 H 4 C CH-4)(dppe) 2 : 11

12 (3a) trans-ru(c CC 6 H 4 Me-4) 2 (dppe) 2 : 12

13 (3b) trans-ru(c CC 6 H 4 C 5 H 11-4) 2 (dppe) 2 : 13

14 (3c) trans-ru(c CC 6 H 4 OMe-4) 2 (dppe) 2 : 14

15 (3d) trans-ru(c CC 6 H 4 CO 2 Me-4) 2 (dppe) 2 : 15

16 (3e) trans-ru(c CC 6 H 4 NO 2-4) 2 (dppe) 2 : 16

17 (3f) trans-ru(c CC 6 H 4 C CSiMe 3-4) 2 (dppe) 2 : 17

18 (3g) trans-ru(c CC 6 H 4 C CCMe 3-4) 2 (dppe) 2 : 18

19 (3h) trans-ru(c CC 6 H 4 NH 2-4) 2 (dppe) 2 : 19

20 (3i) trans-ru(c CC 6 H 4 C CH-4) 2 (dppe) 2 : 20

21 (4) trans-ru(c CC 6 H 4 C CSiMe 3-4)(C CC 6 H 4 NH 2-4)(dppe) 2 : 21

22 22

23 (5) trans-ru(c CC 6 H 4 CO 2 Me-4)(C CC 6 H 4 NH 2-4)(dppe) 2 : 23

24 24

25 (6) trans-ru(c CC 6 H 4 CO 2 Me-4)(C CC 6 H 4 OMe-4)(dppe) 2 : 25

26 26

27 CRYSTALOGRAPHIC DATA Table S1. Crsytal and refinement data for trans-rucl(c CC 6 H 4 C CSiMe 3-4)(dppe) 2 (2f) Empirical formula C 65 H 61 ClP 4 RuSi x 1.5 CH 2 Cl 2 Formula weight Temperature / K 120 Crystal system triclinic Space group P-1 a / Å, b / Å, c / Å (4), (4), (5) /, β/, γ/ (10), (10), (10) Volume / Å (15) Z 2 ρ calc / mg mm µ / mm F(000) 1298 Crystal size / mm Θ range for data collection 2.58 to 57 Index ranges -18 h 18, -19 k 19, -23 l 23 Reflections collected Independent reflections 15588[R(int) = ] Data/restraints/parameters 15588/1/699 Goodness-of-fit on F Final R indexes [I>2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å / Figure S1. A plot of a molecule of 2f showing the atom labelling scheme. 27

28 Table S2. Crystallographically determined bond lengths for 2f. Atom Atom Length/Å Atom Atom Length/Å Ru1 Cl (11) C34 C (7) Ru1 P (11) C35 C (6) Ru1 P (11) C41 C (6) Ru1 P (11) C41 C (6) Ru1 P (12) C42 C (7) Ru1 C (5) C43 C (7) P1 C (4) C44 C (7) P1 C (4) C45 C (6) P1 C (4) C51 C (6) P2 C (4) C51 C (6) P2 C (5) C52 C (6) P2 C (4) C53 C (7) P3 C (4) C54 C (7) P3 C (4) C55 C (6) P3 C (4) C61 C (6) P4 C (4) C61 C (6) P4 C (4) C62 C (6) P4 C (5) C63 C (7) Si C (5) C64 C (7) Si C (6) C65 C (6) Si C (5) C71 C (6) Si C (5) C71 C (6) C1 C (6) C72 C (6) C2 C (6) C73 C (7) C3 C (6) C74 C (7) C3 C (6) C75 C (6) C4 C (6) C81 C (6) C5 C (7) C81 C (6) C6 C (7) C82 C (6) C6 C (7) C83 C (7) C7 C (7) C84 C (7) C9 C (7) C85 C (6) C11 C (6) C91 C (6) C13 C (6) C91 C (6) C21 C (6) C92 C (7) C21 C (6) C93 C (7) C22 C (6) C94 C (7) C23 C (7) C95 C (6) C24 C (7) Cl0A C2SA 1.716(9) C25 C (6) Cl4 C2SA 1.769(9) C31 C (6) Cl1A C2SA 1.722(8) C31 C (6) Cl5 C2SA 1.777(11) C32 C (7) Cl2 C1S 1.769(5) C33 C (7) Cl3 C1S 1.755(5) 28

29 Table S3. Crystallographically determined bond angles for 2f. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 Ru1 Cl (4) C22 C23 C (5) P1 Ru1 P (4) C25 C24 C (5) P1 Ru1 P (4) C24 C25 C (5) P2 Ru1 Cl (4) C25 C26 C (5) P3 Ru1 Cl (4) C32 C31 P (4) P3 Ru1 P (4) C36 C31 P (3) P4 Ru1 Cl (4) C36 C31 C (4) P4 Ru1 P (4) C31 C32 C (5) P4 Ru1 P (4) C34 C33 C (5) P4 Ru1 P (4) C33 C34 C (5) C1 Ru1 Cl (12) C34 C35 C (5) C1 Ru1 P (12) C31 C36 C (4) C1 Ru1 P (12) C42 C41 P (4) C1 Ru1 P (12) C46 C41 P (3) C1 Ru1 P (12) C46 C41 C (4) C11 P1 Ru (14) C43 C42 C (5) C11 P1 C (2) C44 C43 C (5) C21 P1 Ru (14) C45 C44 C (5) C31 P1 Ru (15) C44 C45 C (5) C31 P1 C (2) C45 C46 C (5) C31 P1 C (2) C52 C51 P (3) C12 P2 Ru (14) C52 C51 C (4) C41 P2 Ru (14) C56 C51 P (3) C41 P2 C (2) C53 C52 C (4) C41 P2 C (2) C52 C53 C (4) C51 P2 Ru (15) C55 C54 C (4) C51 P2 C (19) C54 C55 C (5) C13 P3 Ru (14) C55 C56 C (4) C61 P3 Ru (14) C62 C61 P (3) C61 P3 C (2) C66 C61 P (3) C71 P3 Ru (14) C66 C61 C (4) C71 P3 C (19) C63 C62 C (4) C71 P3 C (2) C64 C63 C (4) C14 P4 Ru (14) C65 C64 C (4) C81 P4 Ru (15) C64 C65 C (5) C81 P4 C (2) C61 C66 C (4) C91 P4 Ru (14) C72 C71 P (3) C91 P4 C (2) C76 C71 P (3) C91 P4 C (2) C76 C71 C (4) C10 Si C (3) C73 C72 C (4) C10 Si C (2) C72 C73 C (5) C10 Si C (2) C73 C74 C (4) C16 Si C (3) C74 C75 C (5) C16 Si C (3) C75 C76 C (4) C17 Si C (3) C82 C81 P (4) 29

30 C2 C1 Ru (4) C82 C81 C (4) C1 C2 C (5) C86 C81 P (3) C4 C3 C (4) C81 C82 C (5) C4 C3 C (4) C84 C83 C (5) C8 C3 C (4) C83 C84 C (5) C5 C4 C (4) C84 C85 C (5) C4 C5 C (4) C81 C86 C (5) C5 C6 C (4) C92 C91 P (4) C7 C6 C (4) C92 C91 C (4) C7 C6 C (5) C96 C91 P (4) C6 C7 C (5) C91 C92 C (5) C7 C8 C (5) C94 C93 C (5) C10 C9 C (6) C93 C94 C (5) C9 C10 Si 180.0(7) C96 C95 C (5) C12 C11 P (3) C95 C96 C (4) C11 C12 P (3) Cl0A C2SA Cl (6) C14 C13 P (3) Cl0A C2SA Cl1A 109.1(6) C13 C14 P (3) Cl0A C2SA Cl5 10.1(4) C22 C21 P (4) Cl4 C2SA Cl (5) C26 C21 P (3) Cl1A C2SA Cl4 14.7(3) C26 C21 C (4) Cl1A C2SA Cl5 99.1(5) C23 C22 C (5) Cl3 C1S Cl (3) Table S4. Crystal and refinement data for trans-rucl(c CC 6 H 4 CMe 3-4)(dppe) 2 (2g) Empirical formula C 66 H 61 ClP 4 Ru Formula weight Temperature/K 120 Crystal system triclinic Space group P1 a/å (4) b/å (6) c/å (7) / (10) β/ (10) γ/ (10) Volume/Å (11) Z 1 ρ calc mg/mm m/mm F(000) 578 Crystal size/mm Θ range for data collection 3.48 to 60 30

31 Index ranges -13 h 13, -18 k 18, -19 l 19 Reflections collected Independent reflections 15422[R(int) = ] Data/restraints/parameters 15422/3/641 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å / Flack Parameter 0.0(3) 31

32 Figure S2. Plot of a molecule of 2g showing the atom labelling scheme Table S5. Crystallographically determined bond lengths for 2g. Atom Atom Length/Å Atom Atom Length/Å Ru1 Cl (11) C31 C (6) Ru1 Cl1A 2.437(15) C32 C (6) Ru1 P (10) C33 C (7) Ru1 P (10) C34 C (7) Ru1 P (10) C35 C (6) Ru1 P (10) C41 C (6) Ru1 C (4) C41 C (6) P1 C (4) C42 C (6) P1 C (4) C43 C (8) P1 C (4) C44 C (7) P2 C (4) C45 C (6) P2 C (4) C51 C (6) P2 C (4) C51 C (5) P3 C (4) C52 C (6) P3 C (4) C53 C (7) P3 C (4) C54 C (7) P4 C (4) C55 C (6) P4 C (4) C61 C (6) P4 C (4) C61 C (6) C1 C (5) C62 C (6) C2 C (5) C63 C (7) C3 C (5) C64 C (7) C3 C (4) C65 C (6) C4 C (4) C71 C (6) C5 C (5) C71 C (6) 32

33 C6 C (5) C72 C (6) C6 C (5) C73 C (7) C7 C (4) C74 C (6) C9 C (5) C75 C (6) C10 C (5) C81 C (6) C11 C (5) C81 C (6) C11 C (5) C82 C (6) C11 C (5) C83 C (7) C15 C (5) C84 C (7) C17 C (5) C85 C (6) C21 C (6) C91 C (6) C21 C (6) C91 C (6) C22 C (6) C92 C (6) C23 C (7) C93 C (6) C24 C (6) C94 C (6) C25 C (6) C95 C (6) C31 C (6) Table S6. Crystallographically determined bond angles for 2g. Atom Atom Atom Angle/ Atom Atom Atom Angle/ Cl1A Ru1 Cl (4) C18 C17 P (3) P1 Ru1 Cl (4) C17 C18 P (3) P1 Ru1 Cl1A 89.5(4) C22 C21 P (3) P1 Ru1 P (4) C22 C21 C (4) P1 Ru1 P (3) C26 C21 P (3) P2 Ru1 Cl (4) C23 C22 C (4) P2 Ru1 Cl1A 99.1(4) C22 C23 C (4) P3 Ru1 Cl (4) C25 C24 C (4) P3 Ru1 Cl1A 90.6(4) C24 C25 C (4) P3 Ru1 P (5) C25 C26 C (4) P3 Ru1 P (3) C32 C31 P (3) P3 Ru1 P (4) C36 C31 P (3) P4 Ru1 Cl (4) C36 C31 C (4) P4 Ru1 Cl1A 80.0(4) C33 C32 C (4) P4 Ru1 P (4) C34 C33 C (5) C1 Ru1 Cl (13) C33 C34 C (4) C1 Ru1 Cl1A 2.2(5) C34 C35 C (4) C1 Ru1 P (13) C31 C36 C (4) C1 Ru1 P (13) C42 C41 P (3) C1 Ru1 P (13) C42 C41 C (4) C1 Ru1 P (13) C46 C41 P (3) C15 P1 Ru (13) C41 C42 C (4) C21 P1 Ru (13) C44 C43 C (5) C21 P1 C (18) C43 C44 C (4) C21 P1 C (19) C46 C45 C (5) 33

34 C31 P1 Ru (14) C45 C46 C (4) C31 P1 C (18) C52 C51 P (3) C16 P2 Ru (14) C56 C51 P (3) C16 P2 C (19) C56 C51 C (4) C41 P2 Ru (14) C53 C52 C (4) C41 P2 C (19) C54 C53 C (4) C41 P2 C (19) C55 C54 C (4) C51 P2 Ru (13) C54 C55 C (4) C17 P3 Ru (13) C51 C56 C (4) C61 P3 Ru (13) C62 C61 P (3) C61 P3 C (17) C62 C61 C (4) C61 P3 C (18) C66 C61 P (3) C71 P3 Ru (13) C63 C62 C (4) C71 P3 C (18) C62 C63 C (4) C18 P4 Ru (13) C65 C64 C (4) C81 P4 Ru (13) C64 C65 C (5) C81 P4 C (18) C61 C66 C (4) C81 P4 C (19) C72 C71 P (3) C91 P4 Ru (13) C76 C71 P (3) C91 P4 C (19) C76 C71 C (4) C2 C1 Ru (4) C73 C72 C (4) C1 C2 C (4) C74 C73 C (4) C2 C3 C (3) C75 C74 C (4) C8 C3 C (3) C74 C75 C (4) C8 C3 C (3) C71 C76 C (4) C5 C4 C (3) C82 C81 P (3) C6 C5 C (3) C86 C81 P (3) C5 C6 C (3) C86 C81 C (4) C5 C6 C (3) C83 C82 C (4) C7 C6 C (3) C82 C83 C (5) C6 C7 C (3) C85 C84 C (4) C7 C8 C (3) C84 C85 C (5) C10 C9 C (5) C85 C86 C (4) C9 C10 C (4) C92 C91 P (3) C10 C11 C (3) C92 C91 C (4) C10 C11 C (3) C96 C91 P (3) C10 C11 C (3) C91 C92 C (4) C12 C11 C (3) C92 C93 C (4) C12 C11 C (3) C95 C94 C (4) C14 C11 C (3) C94 C95 C (4) C16 C15 P (3) C95 C96 C (4) C15 C16 P (3) 34

35 Table S7. Crystal and refinement details for trans-rucl(c CC 6 H 4 C CH-4)(dppe) 2 (2i) Empirical formula C 62 H 53 ClP 4 Ru Formula weight Temperature/K 120 Wavelength/Å Crystal system monoclinic Space group P2 1 /c a/å (7) b/å (8) c/å (10) / β/ (6) γ/ Volume/Å (4) Z 4 ρ calc mg/mm m/mm F(000) Crystal size/mm Θ range for data collection 2.68 to 57 Index ranges -15 h 15, -31 k 31, -26 l 25 Reflections collected Independent reflections 13451[R(int) = ] Data/restraints/parameters 13451/0/613 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

36 Figure S3. A plot of a molecule of 2i showing the atom labelling scheme. Table S8. Crystallographically determined bond lengths for 2i. Atom Atom Length/Å Atom Atom Length/Å Ru1 Cl (6) C33 C (4) Ru1 P (6) C34 C (4) Ru1 P (5) C35 C (3) Ru1 P (6) C41 C (3) Ru1 P (6) C41 C (3) Ru1 C (2) C42 C (3) P1 C (2) C43 C (4) P1 C (2) C44 C (4) P1 C (2) C45 C (3) P2 C (2) C51 C (3) P2 C (2) C51 C (3) P2 C (2) C52 C (3) P3 C (2) C53 C (3) P3 C (2) C54 C (4) P3 C (2) C55 C (3) P4 C (2) C61 C (3) P4 C (2) C61 C (3) P4 C (2) C62 C (3) C1 C (3) C63 C (4) C2 C (3) C64 C (4) C3 C (3) C65 C (4) C3 C (3) C71 C (3) C4 C (3) C71 C (3) C5 C (3) C72 C (3) C6 C (3) C73 C (4) 36

37 C6 C (3) C74 C (4) C7 C (3) C75 C (3) C9 C (4) C81 C (3) C11 C (3) C81 C (3) C13 C (3) C82 C (3) C21 C (3) C83 C (4) C21 C (3) C84 C (4) C22 C (3) C85 C (3) C23 C (4) C91 C (3) C24 C (4) C91 C (3) C25 C (3) C92 C (3) C31 C (3) C93 C (4) C31 C (3) C94 C (4) C32 C (3) C95 C (4) Table S9. Crystallographically determined bond angles for 2i. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 Ru1 Cl (19) C24 C23 C (2) P1 Ru1 P (19) C25 C24 C (2) P1 Ru1 P (19) C24 C25 C (2) P2 Ru1 Cl (19) C25 C26 C (2) P2 Ru1 P (19) C32 C31 P (17) P2 Ru1 P (19) C36 C31 P (16) P2 Ru1 P (19) C36 C31 C (2) P3 Ru1 Cl (19) C33 C32 C (2) P3 Ru1 P (19) C34 C33 C (2) P4 Ru1 Cl (2) C35 C34 C (2) C1 Ru1 Cl (6) C34 C35 C (2) C1 Ru1 P (6) C31 C36 C (2) C1 Ru1 P (6) C42 C41 P (17) C1 Ru1 P (6) C42 C41 C (2) C1 Ru1 P (6) C46 C41 P (16) C11 P1 Ru (7) C43 C42 C (2) C11 P1 C (10) C44 C43 C (2) C21 P1 Ru (7) C43 C44 C (2) C31 P1 Ru (7) C44 C45 C (2) C31 P1 C (9) C45 C46 C (2) C31 P1 C (9) C52 C51 P (16) C12 P2 Ru (7) C52 C51 C (19) C41 P2 Ru (7) C56 C51 P (16) C41 P2 C (10) C53 C52 C (2) C41 P2 C (9) C54 C53 C (2) 37

38 C51 P2 Ru (7) C55 C54 C (2) C51 P2 C (9) C54 C55 C (2) C13 P3 Ru (7) C55 C56 C (2) C61 P3 Ru (7) C62 C61 P (17) C61 P3 C (10) C62 C61 C (2) C61 P3 C (10) C66 C61 P (16) C71 P3 Ru (7) C61 C62 C (2) C71 P3 C (10) C64 C63 C (2) C14 P4 Ru (7) C63 C64 C (2) C81 P4 Ru (7) C66 C65 C (2) C81 P4 C (10) C65 C66 C (2) C91 P4 Ru (7) C72 C71 P (17) C91 P4 C (10) C76 C71 P (17) C91 P4 C (10) C76 C71 C (2) C2 C1 Ru (2) C73 C72 C (2) C1 C2 C (2) C74 C73 C (2) C4 C3 C (2) C75 C74 C (2) C8 C3 C (19) C74 C75 C (2) C8 C3 C (2) C71 C76 C (2) C5 C4 C (2) C82 C81 P (17) C4 C5 C (2) C86 C81 P (17) C5 C6 C (2) C86 C81 C (2) C7 C6 C (2) C83 C82 C (2) C7 C6 C (2) C84 C83 C (2) C8 C7 C (2) C83 C84 C (2) C7 C8 C (2) C84 C85 C (2) C10 C9 C (3) C81 C86 C (2) C12 C11 P (14) C92 C91 P (17) C11 C12 P (15) C96 C91 P (18) C14 C13 P (14) C96 C91 C (2) C13 C14 P (15) C93 C92 C (2) C22 C21 P (16) C94 C93 C (3) C22 C21 C (2) C95 C94 C (2) C26 C21 P (17) C94 C95 C (3) C21 C22 C (2) C91 C96 C (2) 38

39 Table S10. Crystal and refinement data for trans-ru(c CC 6 H 4 Me-4) 2 (dppe) 2 (3a) Empirical formula C 70 H 62 P 4 Ru Formula weight Temperature/K 120 Crystal system triclinic Space group P-1 a/å (4) b/å (6) c/å (6) / (10) β/ (10) γ/ (10) Volume/Å (11) Z 1 ρ calc mg/mm m/mm F(000) 586 Crystal size/mm Theta range for data collection 3.48 to 59 Index ranges -13 h 13, -17 k 17, -18 l 18 Reflections collected Independent reflections 7679[R(int) = ] Data/restraints/parameters 7679/0/341 Goodness-of-fit on F Final R indexes [I>2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

40 Figure S4. A plot of a molecule of 3a showing the atom labelling scheme. Table S11. Crystallographically determined bond lengths for 3a. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (5) C21 C (3) Ru1 P (5) C22 C (3) Ru1 P (5) C23 C (3) Ru1 P (5) C24 C (3) Ru1 C (2) C25 C (3) Ru1 C (2) C31 C (3) P1 C (2) C31 C (3) P1 C (2) C32 C (3) P1 C (2) C33 C (3) P2 C (2) C34 C (3) P2 C (2) C35 C (3) P2 C (2) C41 C (3) C1 C (3) C41 C (3) C2 C (3) C42 C (3) C3 C (3) C43 C (3) C3 C (3) C44 C (3) C4 C (3) C45 C (3) C5 C (3) C51 C (3) C6 C (3) C51 C (3) C6 C (3) C52 C (3) C7 C (3) C53 C (3) C10 C (3) C54 C (3) C21 C (3) C55 C (3) 40

41 Table S12. Crystallographically determined bond angles for 3a. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 1 Ru1 P (2) C6 C7 C (2) P1 1 Ru1 P (18) C7 C8 C (2) P1 Ru1 P (17) C11 C10 P (13) P1 1 Ru1 P (18) C10 C11 P (13) P1 Ru1 P (18) C22 C21 P (15) P2 Ru1 P C22 C21 C (18) C1 1 Ru1 P (6) C26 C21 P (15) C1 Ru1 P (6) C23 C22 C (2) C1 Ru1 P (6) C24 C23 C (2) C1 1 Ru1 P (6) C23 C24 C (2) C1 1 Ru1 P (5) C26 C25 C (2) C1 Ru1 P (5) C25 C26 C (2) C1 1 Ru1 P (5) C32 C31 P (16) C1 Ru1 P (5) C36 C31 P (15) C1 Ru1 C C36 C31 C (19) C10 P1 Ru (7) C33 C32 C (2) C10 P1 C (9) C34 C33 C (2) C21 P1 Ru (7) C33 C34 C (2) C31 P1 Ru (6) C36 C35 C (2) C31 P1 C (9) C35 C36 C (2) C31 P1 C (9) C42 C41 P (16) C11 P2 Ru (7) C42 C41 C (19) C41 P2 Ru (7) C46 C41 P (16) C41 P2 C (9) C41 C42 C (2) C41 P2 C (9) C44 C43 C (2) C51 P2 Ru (7) C43 C44 C (2) C51 P2 C (9) C44 C45 C (2) C2 C1 Ru (17) C45 C46 C (2) C1 C2 C (2) C52 C51 P (15) C4 C3 C (19) C56 C51 P (15) C8 C3 C (2) C56 C51 C (18) C8 C3 C (19) C53 C52 C (2) C5 C4 C (2) C54 C53 C (2) C6 C5 C (2) C55 C54 C (19) C5 C6 C (2) C54 C55 C (2) C7 C6 C (2) C51 C56 C (19) C7 C6 C (2) 41

42 Table S13. Crystal and refinement data for trans-ru(c CC 6 H 4 C 5 H 11-4) 2 (dppe) 2 (3b) Empirical formula C 78 H 78 P 4 Ru x 2 CHCl 3 Formula weight Temperature/K 120 Crystal system triclinic Space group P-1 a/å (2) b/å (3) c/å (4) / (10) β/ (10) γ/ (10) Volume/Å (7) Z 1 ρ calc mg/mm m/mm F(000) 766 Crystal size/mm Θ range for data collection 3.26 to 60 Index ranges -13 h 13, -18 k 18, -21 l 21 Reflections collected Independent reflections 10417[R(int) = ] Data/restraints/parameters 10417/0/572 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

43 Figure S5. A plot of a molecule of 3b showing the atom labelling scheme. Table S14. Crystallographically determined bond lengths for 3b. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (5) C21 C (2) Ru1 P (5) C22 C (2) Ru1 P (5) C23 C (3) Ru1 P (5) C24 C (3) Ru1 C (16) C25 C (2) Ru1 C (16) C31 C (2) P1 C (17) C31 C (2) P1 C (17) C32 C (2) P1 C (16) C33 C (3) P2 C (17) C34 C (3) P2 C (17) C35 C (2) P2 C (16) C41 C (2) C1 C (2) C41 C (2) C2 C (2) C42 C (2) C3 C (2) C43 C (3) C3 C (2) C44 C (3) C4 C (2) C45 C (2) C5 C (3) C51 C (2) C6 C (3) C51 C (2) C6 C (3) C52 C (2) C7 C (2) C53 C (3) C9 C (3) C54 C (3) C10 C (3) C55 C (2) C11 C (3) Cl1 C1S 1.760(2) C12 C (3) Cl2 C1S 1.758(2) C14 C (2) Cl3 C1S 1.766(2) 43

44 C21 C (2) Table S15. Crystallographically determined bond angles for 3b. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 Ru1 P C9 C10 C (16) P2 Ru1 P (16) C12 C11 C (17) P2 1 Ru1 P (16) C13 C12 C (18) P2 1 Ru1 P (16) C15 C14 P (11) P2 Ru1 P (16) C14 C15 P (11) P2 Ru1 P C22 C21 P (12) C1 1 Ru1 P (4) C22 C21 C (15) C1 Ru1 P (4) C26 C21 P (13) C1 1 Ru1 P (4) C21 C22 C (16) C1 Ru1 P (4) C24 C23 C (17) C1 Ru1 P (4) C23 C24 C (17) C1 1 Ru1 P (4) C24 C25 C (17) C1 1 Ru1 P (4) C25 C26 C (17) C1 Ru1 P (4) C32 C31 P (13) C1 1 Ru1 C C36 C31 P (13) C14 P1 Ru (6) C36 C31 C (15) C14 P1 C (8) C33 C32 C (16) C21 P1 Ru (5) C34 C33 C (17) C31 P1 Ru (5) C35 C34 C (17) C31 P1 C (8) C34 C35 C (17) C31 P1 C (7) C31 C36 C (16) C15 P2 Ru (6) C42 C41 P (13) C41 P2 Ru (5) C46 C41 P (13) C41 P2 C (8) C46 C41 C (16) C41 P2 C (7) C43 C42 C (17) C51 P2 Ru (6) C44 C43 C (18) C51 P2 C (8) C43 C44 C (17) C2 C1 Ru (14) C44 C45 C (17) C1 C2 C (17) C45 C46 C (17) C4 C3 C (16) C52 C51 P (12) C8 C3 C (15) C52 C51 C (15) C8 C3 C (16) C56 C51 P (13) C5 C4 C (17) C51 C52 C (16) C6 C5 C (17) C54 C53 C (17) C5 C6 C (16) C53 C54 C (16) C5 C6 C (18) C56 C55 C (17) C7 C6 C (18) C55 C56 C (16) C8 C7 C (17) Cl1 C1S Cl (11) C7 C8 C (16) Cl2 C1S Cl (11) C6 C9 C (16) Cl2 C1S Cl (12) 44

45 Table S16. Crystal and refinement data for trans-ru(c CC 6 H 4 OMe-4) 2 (dppe) 2 (3c) Empirical formula C 70 H 62 O 2 P 4 Ru x C 7 H 7 Formula weight Temperature/K 120 Crystal system triclinic Space group P-1 a/å (4) b/å (5) c/å (6) / (10) β/ (10) γ/ (10) Volume/Å (11) Z 1 ρ calc mg/mm m/mm F(000) 651 Crystal size/mm Θ range for data collection 3.08 to 60 Index ranges -12 h 12, -17 k 17, -19 l 18 Reflections collected Independent reflections 8842[R(int) = ] Data/restraints/parameters 8842/0/518 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

46 Figure S6. A plot of a molecule of 3c showing the atom labelling scheme. Table S17. Crystallographically determined bond angles for 3c. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (4) C23 C (3) Ru1 P (4) C24 C (3) Ru1 P (4) C25 C (2) Ru1 P (4) C31 C (2) Ru1 C (16) C31 C (2) Ru1 C (16) C32 C (2) P1 C (16) C33 C (3) P1 C (16) C34 C (3) P1 C (16) C35 C (2) P2 C (16) C41 C (2) P2 C (16) C41 C (2) P2 C (16) C42 C (2) O1 C (2) C43 C (3) O1 C (2) C44 C (3) C1 C (2) C45 C (2) C2 C (2) C51 C (2) C3 C (2) C51 C (2) C3 C (2) C52 C (2) C4 C (2) C53 C (3) C5 C (3) C54 C (3) C6 C (3) C55 C (2) C7 C (2) C1S C2S 1.394(3) C10 C (2) C1S C3S (3) C21 C (2) C2S C3S 1.387(3) C21 C (2) C2S C4S 1.524(5) 46

47 C22 C (2) C3S C1S (3) Table S18. Crystallographically determined bond angles for 3c. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 1 Ru1 P C11 C10 P (11) P2 Ru1 P (14) C10 C11 P (11) P2 1 Ru1 P (14) C22 C21 P (12) P2 1 Ru1 P (14) C22 C21 C (15) P2 Ru1 P (14) C26 C21 P (12) P2 1 Ru1 P C21 C22 C (16) C1 Ru1 P (4) C24 C23 C (17) C1 1 Ru1 P (4) C23 C24 C (17) C1 Ru1 P (4) C24 C25 C (17) C1 1 Ru1 P (4) C25 C26 C (17) C1 1 Ru1 P (4) C32 C31 P (12) C1 Ru1 P (4) C36 C31 P (13) C1 Ru1 P (4) C36 C31 C (15) C1 1 Ru1 P (4) C33 C32 C (16) C1 Ru1 C C34 C33 C (17) C10 P1 Ru (5) C35 C34 C (16) C10 P1 C (7) C34 C35 C (16) C21 P1 Ru (5) C35 C36 C (16) C31 P1 Ru (5) C42 C41 P (12) C31 P1 C (7) C46 C41 P (13) C31 P1 C (7) C46 C41 C (15) C11 P2 Ru (5) C43 C42 C (16) C41 P2 Ru (5) C44 C43 C (16) C41 P2 C (7) C43 C44 C (16) C51 P2 Ru (5) C44 C45 C (17) C51 P2 C (7) C45 C46 C (16) C51 P2 C (7) C52 C51 P (12) C6 O1 C (15) C52 C51 C (15) C2 C1 Ru (14) C56 C51 P (12) C1 C2 C (18) C51 C52 C (16) C4 C3 C (16) C54 C53 C (17) C8 C3 C (15) C53 C54 C (17) C8 C3 C (15) C56 C55 C (17) C5 C4 C (16) C55 C56 C (16) C4 C5 C (17) C3S 2 C1S C2S 120.9(2) O1 C6 C (16) C1S C2S C4S 122.1(3) O1 C6 C (16) C3S C2S C1S 118.2(2) C7 C6 C (15) C3S C2S C4S 119.6(3) C6 C7 C (16) C1S 2 C3S C2S 120.9(2) C7 C8 C (16) 47

48 Table S19. Crystal and refinement data for trans-ru(c CC 6 H 4 CO 2 Me-4) 2 (dppe) 2 (3d) Empirical formula C 72 H 62 O 4 P 4 Ru x C 7 H 8 Formula weight Temperature/K 120 Crystal system triclinic Space group P-1 a/å (3) b/å (4) c/å (4) / (10) β/ (10) γ/ (10) Volume/Å (8) Z 1 ρ calc mg/mm m/mm F(000) 680 Crystal size/mm Θ range for data collection 3.14 to 60 Index ranges -13 h 13, -18 k 18, -19 l 19 Reflections collected Independent reflections 9066[R(int) = ] Data/restraints/parameters 9066/0/539 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

49 Figure S7. A plot of a molecule of 3d showing the atom labelling scheme. Table S20. Crystallographically determined bond lengths for 3d. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (5) C22 C (2) Ru1 P (5) C23 C (3) Ru1 P (4) C24 C (3) Ru1 P (4) C25 C (3) Ru1 C (18) C31 C (2) Ru1 C (18) C31 C (2) P1 C (18) C32 C (3) P1 C (17) C33 C (3) P1 C (17) C34 C (3) P2 C (18) C35 C (2) P2 C (17) C41 C (2) P2 C (17) C41 C (2) O1 C (2) C42 C (3) O1 C (2) C43 C (3) O2 C (2) C44 C (3) C1 C (2) C45 C (3) C2 C (2) C51 C (2) C3 C (3) C51 C (2) C3 C (3) C52 C (3) C4 C (2) C53 C (3) C5 C (3) C54 C (3) C6 C (3) C55 C (3) C6 C (2) C1S C2S 1.396(4) C7 C (3) C1S C3S (4) 49

50 C11 C (2) C1S C4S 1.506(5) C21 C (2) C2S C3S 1.367(4) C21 C (2) C3S C1S (4) Table S21. Crystallographically determined bond angles for 3d. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 1 Ru1 P O2 C9 O (17) P2 1 Ru1 P (17) O2 C9 C (18) P2 Ru1 P (17) C12 C11 P (12) P2 Ru1 P (18) C11 C12 P (12) P2 1 Ru1 P (17) C22 C21 P (14) P2 Ru1 P C22 C21 C (16) C1 1 Ru1 P (5) C26 C21 P (13) C1 Ru1 P (5) C23 C22 C (18) C1 1 Ru1 P (5) C24 C23 C (18) C1 Ru1 P (5) C23 C24 C (17) C1 1 Ru1 P (5) C24 C25 C (18) C1 Ru1 P (5) C25 C26 C (17) C1 Ru1 P (5) C32 C31 P (13) C1 1 Ru1 P (5) C36 C31 P (13) C1 Ru1 C (8) C36 C31 C (16) C11 P1 Ru (6) C33 C32 C (17) C11 P1 C (8) C32 C33 C (18) C21 P1 Ru (6) C35 C34 C (17) C21 P1 C (8) C34 C35 C (18) C21 P1 C (8) C35 C36 C (17) C31 P1 Ru (6) C42 C41 P (14) C12 P2 Ru (6) C46 C41 P (14) C41 P2 Ru (6) C46 C41 C (16) C41 P2 C (8) C43 C42 C (18) C41 P2 C (8) C44 C43 C (19) C51 P2 Ru (6) C45 C44 C (18) C51 P2 C (8) C44 C45 C (18) C9 O1 C (18) C45 C46 C (18) C2 C1 Ru (15) C52 C51 P (13) C1 C2 C (19) C56 C51 P (13) C4 C3 C (16) C56 C51 C (16) C4 C3 C (16) C53 C52 C (17) C8 C3 C (16) C52 C53 C (17) C5 C4 C (17) C55 C54 C (17) C4 C5 C (18) C54 C55 C (18) C5 C6 C (17) C55 C56 C (17) C7 C6 C (17) C2S C1S C4S 122.1(3) C7 C6 C (17) C3S 2 C1S C2S 118.6(2) C8 C7 C (18) C3S 2 C1S C4S 119.2(3) C7 C8 C (18) C3S C2S C1S 120.8(2) 50

51 O1 C9 C (17) C2S C3S C1S (2) Table S22. Crystal and refinement data for trans-ru(c CC 6 H 4 C CSiMe 3-4) 2 (dppe) 2 (3f) Empirical formula C 78 H 74 Si 2 P 4 Ru Formula weight Temperature/K 120 Crystal system triclinic Space group P-1 a/å (4) b/å (5) c/å (6) / (2) β/ (3) γ/ (2) Volume/Å (12) Z 1 ρ calc mg/mm m/mm F(000) 674 Crystal size/mm Θ range for data collection 3 to 57 Index ranges -12 h 12, -18 k 18, -19 l 19 Reflections collected Independent reflections 8224[R(int) = ] Data/restraints/parameters 8224/0/533 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

52 Figure S8. A plot of a molecule of 3f. Table S23. Crystallographically determined bond lengths for 3f. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (6) C14 C (4) Ru1 P (6) C21 C (4) Ru1 P (7) C21 C (4) Ru1 P (7) C22 C (4) Ru1 C (3) C23 C (4) Ru1 C (3) C24 C (4) P1 C (3) C25 C (4) P1 C (3) C31 C (4) P1 C (3) C31 C (4) P2 C (3) C32 C (4) P2 C (3) C33 C (4) P2 C (3) C34 C (5) Si1 C (3) C35 C (4) Si1 C (4) C41 C (4) Si1 C (4) C41 C (4) Si1 C (4) C42 C (4) C1 C (4) C43 C (5) C2 C (4) C44 C (5) C3 C (4) C45 C (4) C3 C (4) C51 C (4) C4 C (4) C51 C (4) C5 C (4) C52 C (4) C6 C (4) C53 C (4) C6 C (4) C54 C (4) C7 C (4) C55 C (4) 52

53 C9 C (4) Table S24. Crystallographically determined bond angles for 3f. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 1 Ru1 P C5 C6 C (3) P2 1 Ru1 P (2) C7 C6 C (3) P2 Ru1 P (2) C8 C7 C (3) P2 Ru1 P (2) C7 C8 C (3) P2 1 Ru1 P (2) C10 C9 C (4) P2 Ru1 P C9 C10 Si (4) C1 1 Ru1 P (7) C15 C14 P (18) C1 Ru1 P (7) C14 C15 P (18) C1 1 Ru1 P (7) C22 C21 P (19) C1 Ru1 P (7) C22 C21 C (2) C1 Ru1 P (7) C26 C21 P (2) C1 1 Ru1 P (7) C23 C22 C (2) C1 1 Ru1 P (7) C24 C23 C (3) C1 Ru1 P (7) C23 C24 C (3) C1 1 Ru1 C C26 C25 C (3) C14 P1 Ru (9) C25 C26 C (3) C21 P1 Ru (8) C32 C31 P (2) C21 P1 C (12) C36 C31 P (2) C31 P1 Ru (8) C36 C31 C (3) C31 P1 C (12) C33 C32 C (3) C31 P1 C (12) C34 C33 C (3) C15 P2 Ru (9) C35 C34 C (3) C41 P2 Ru (9) C34 C35 C (3) C41 P2 C (12) C35 C36 C (3) C41 P2 C (12) C42 C41 P (2) C51 P2 Ru (9) C46 C41 P (2) C51 P2 C (12) C46 C41 C (3) C10 Si1 C (17) C43 C42 C (3) C10 Si1 C (19) C42 C43 C (3) C10 Si1 C (16) C45 C44 C (3) C12 Si1 C (2) C44 C45 C (3) C12 Si1 C (18) C45 C46 C (3) C13 Si1 C (18) C52 C51 P (2) C2 C1 Ru (2) C56 C51 P (2) C1 C2 C (3) C56 C51 C (3) C4 C3 C (3) C53 C52 C (3) C8 C3 C (3) C54 C53 C (3) C8 C3 C (3) C53 C54 C (3) C5 C4 C (3) C56 C55 C (3) C4 C5 C (3) C55 C56 C (3) C5 C6 C (3) 53

54 Table S25. Crystal and refinement data for trans-ru(c CC 6 H 4 C CCMe 3-4) 2 (dppe) 2 (3g) Empirical formula C 84 H 78 Br 0.1 Cl 12 P 4 Ru Formula weight Temperature/K Crystal system triclinic Space group P-1 a/å (4) b/å (4) c/å (6) / (10) β/ (10) γ/ (10) Volume/Å (13) Z 1 ρ calc mg/mm m/mm F(000) 894 Crystal size/mm Theta range for data collection 2.6 to 59 Index ranges -14 h 14, -17 k 17, -22 l 22 Reflections collected Independent reflections 11468[R(int) = ] Data/restraints/parameters 11468/1/464 Goodness-of-fit on F Final R indexes [I>2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

55 Figure S9. A plot of a molecule of 3g showing the atom labelling scheme. Table S26. Crystallographically determined bond lengths for 3g. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (5) C21 C (3) Ru1 P (5) C22 C (3) Ru1 P (5) C23 C (4) Ru1 P (5) C24 C (4) Ru1 C (2) C25 C (3) Ru1 C (2) C31 C (3) Br7 C (7) C31 C (3) P1 C (2) C32 C (3) P1 C (2) C33 C (4) P1 C (2) C34 C (4) P2 C (2) C35 C (3) P2 C (2) C41 C (3) P2 C (2) C41 C (3) C1 C (3) C42 C (3) C2 C (3) C43 C (4) C3 C (3) C44 C (4) C3 C (3) C45 C (3) C4 C (3) C51 C (3) C5 C (4) C51 C (3) C6 C (4) C52 C (3) C6 C (4) C53 C (3) C7 C (3) C54 C (3) C9 C (3) C55 C (3) C10 C (4) Cl1 C1S 1.757(3) 55

56 C11 C (5) Cl2 C1S 1.747(3) C11 C (4) Cl3 C1S 1.754(3) C11 C (4) Cl4 C2S 1.748(5) C15 C (3) Cl5 C2S 1.772(5) C21 C (3) Cl6 C2S 1.749(4) Table S27. Crystallographically determined bond angles for 3g. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 1 Ru1 P (19) C10 C11 C (2) P1 1 Ru1 P (17) C10 C11 C (2) P1 Ru1 P (17) C13 C11 C (2) P1 1 Ru1 P (17) C14 C11 C (3) P1 Ru1 P (17) C14 C11 C (2) P2 Ru1 P (1) C16 C15 P (14) C1 1 Ru1 P (5) C15 C16 P (14) C1 Ru1 P (5) C22 C21 P (17) C1 1 Ru1 P (6) C26 C21 P (15) C1 Ru1 P (5) C26 C21 C (2) C1 1 Ru1 P (5) C23 C22 C (2) C1 Ru1 P (5) C24 C23 C (2) C1 1 Ru1 P (5) C23 C24 C (2) C1 Ru1 P (5) C24 C25 C (2) C1 Ru1 C (1) C21 C26 C (2) C15 P1 Ru (7) C32 C31 P (16) C21 P1 Ru (7) C36 C31 P (17) C21 P1 C (10) C36 C31 C (2) C21 P1 C (10) C33 C32 C (2) C31 P1 Ru (7) C34 C33 C (2) C31 P1 C (10) C35 C34 C (2) C16 P2 Ru (7) C34 C35 C (2) C16 P2 C (9) C35 C36 C (2) C41 P2 Ru (7) C42 C41 P (16) C41 P2 C (9) C42 C41 C (19) C41 P2 C (9) C46 C41 P (16) C51 P2 Ru (7) C43 C42 C (2) C2 C1 Ru (17) C44 C43 C (2) C1 C2 C (2) C43 C44 C (2) C4 C3 C (2) C44 C45 C (2) C8 C3 C (2) C45 C46 C (2) C8 C3 C (2) C52 C51 P (16) C5 C4 C (2) C56 C51 P (15) C4 C5 C (2) C56 C51 C (19) C5 C6 Br (3) C53 C52 C (2) C5 C6 C (2) C54 C53 C (2) C5 C6 C (2) C55 C54 C (2) C7 C6 Br (3) C54 C55 C (2) C7 C6 C (2) C55 C56 C (2) 56

57 C9 C6 Br7 15.5(2) Cl2 C1S Cl (16) C8 C7 C (2) Cl2 C1S Cl (15) C7 C8 C (2) Cl3 C1S Cl (14) C10 C9 C (3) Cl4 C2S Cl (19) C9 C10 C (3) Cl4 C2S Cl (3) C10 C11 C (2) Cl6 C2S Cl (2) Table S28. Crystal and refinement data for trans-ru(c CC 6 H 4 NH 2-4) 2 (dppe) 2 (3h) Empirical formula C 68 H 60 N 2 P 4 Ru Formula weight Temperature/K 120 Crystal system triclinic Space group P-1 a/å (3) b/å (4) c/å (4) / (10) β/ (10) γ/ (10) Volume/Å (7) Z 1 ρ calc mg/mm m/mm F(000) Crystal size/mm Θ range for data collection 3.5 to 59 Index ranges -12 h 12, -18 k 18, -18 l 18 Reflections collected Independent reflections 7635[R(int) = ] Data/restraints/parameters 7635/0/460 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

58 Figure S10. A plot of a molecule of 3h showing the atom labelling scheme. Table S29. Crystallographically determined bond lengths for 3h. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (5) C11 C (3) Ru1 P (5) C12 C (3) Ru1 P (5) C13 C (3) Ru1 P (5) C14 C (3) Ru1 C (2) C15 C (3) Ru1 C (2) C21 C (3) P1 C (2) C21 C (3) P1 C (2) C22 C (3) P1 C (2) C23 C (4) P2 C (2) C24 C (4) P2 C (2) C25 C (3) P2 C (2) C31 C (3) N1 C (3) C31 C (3) C1 C (3) C32 C (3) C2 C (3) C33 C (3) C3 C (3) C34 C (3) C3 C (3) C35 C (3) C4 C (4) C41 C (3) C5 C (4) C41 C (3) C6 C (4) C42 C (3) C7 C (3) C43 C (4) C9 C (3) C44 C (4) C11 C (3) C45 C (3) 58

59 Table S30. Crystallographically determined bond angles for 3h. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 1 Ru1 P C6 C7 C (2) P1 1 Ru1 P (18) C7 C8 C (2) P1 Ru1 P (18) C10 C9 P (14) P1 1 Ru1 P (18) C9 C10 P (14) P1 Ru1 P (18) C12 C11 P (16) P2 Ru1 P (2) C12 C11 C (19) C1 Ru1 P (6) C16 C11 P (16) C1 1 Ru1 P (6) C11 C12 C (2) C1 Ru1 P (6) C14 C13 C (2) C1 1 Ru1 P (6) C13 C14 C (2) C1 Ru1 P (6) C16 C15 C (2) C1 1 Ru1 P (6) C15 C16 C (2) C1 Ru1 P (6) C22 C21 P (17) C1 1 Ru1 P (6) C26 C21 P (17) C1 1 Ru1 C (11) C26 C21 C (2) C9 P1 Ru (7) C21 C22 C (2) C11 P1 Ru (7) C24 C23 C (2) C11 P1 C (10) C23 C24 C (2) C21 P1 Ru (7) C24 C25 C (3) C21 P1 C (10) C21 C26 C (2) C21 P1 C (10) C32 C31 P (16) C10 P2 Ru (7) C32 C31 C (19) C10 P2 C (10) C36 C31 P (16) C31 P2 Ru (7) C31 C32 C (2) C41 P2 Ru (7) C34 C33 C (2) C41 P2 C (10) C33 C34 C (2) C41 P2 C (9) C36 C35 C (2) C2 C1 Ru (19) C35 C36 C (2) C1 C2 C (2) C42 C41 P (16) C4 C3 C (2) C46 C41 P (16) C4 C3 C (2) C46 C41 C (19) C8 C3 C (2) C43 C42 C (2) C5 C4 C (3) C44 C43 C (2) C6 C5 C (3) C45 C44 C (2) C5 C6 N (3) C44 C45 C (2) C5 C6 C (2) C45 C46 C (2) C7 C6 N (3) 59

60 Table S31. Crystal and refinement data for trans-ru(c CC 6 H 4 C CH-4) 2 (dppe) 2 (3i) Empirical formula C 72 H 58 P 4 Ru x CH 2 Cl 2 Formula weight Temperature/K 120 Crystal system triclinic Space group P-1 a/å (2) b/å (3) c/å (6) / (10) β/ (10) γ/ (10) Volume/Å (12) Z 2 ρ calc mg/mm m/mm F(000) 1272 Crystal size/mm Θ range for data collection 3.2 to 58 Index ranges -13 h 13, -17 k 17, -32 l 32 Reflections collected Independent reflections 15586[R(int) = ] Data/restraints/parameters 15586/0/724 Goodness-of-fit on F Final R indexes [I>=2σ (I)] R 1 = , wr 2 = Final R indexes [all data] R 1 = , wr 2 = Largest diff. peak/hole / e Å /

61 Figure S10. A plot of a molecule of 3i showing the atom labelling scheme. Table S32. Crystallographically determined bond lengths for 3i. Atom Atom Length/Å Atom Atom Length/Å Ru1 P (7) Ru2 P (7) Ru1 P (7) Ru2 P (7) Ru1 P (7) Ru2 P (7) Ru1 P (7) Ru2 C (3) Ru1 C (3) Ru2 C (3) Ru1 C (3) P3 C (3) P1 C (3) P3 C (3) P1 C (3) P3 C (3) P1 C (3) P4 C (3) P2 C (3) P4 C (3) P2 C (3) P4 C (3) P2 C (3) C101 C (4) C1 C (4) C102 C (4) C2 C (4) C103 C (4) C3 C (4) C103 C (4) C3 C (4) C104 C (4) C4 C (4) C105 C (4) C5 C (5) C106 C (4) C6 C (5) C106 C (4) C6 C (4) C107 C (4) C7 C (4) C109 C (5) C9 C (5) C111 C (4) C11 C (4) C121 C (4) C21 C (4) C121 C (4) 61

62 C21 C (4) C122 C (4) C22 C (4) C123 C (5) C23 C (4) C124 C (5) C24 C (4) C125 C (5) C25 C (4) C131 C (4) C31 C (4) C131 C (4) C31 C (4) C132 C (4) C32 C (4) C133 C (5) C33 C (4) C134 C (5) C34 C (4) C135 C (4) C35 C (4) C141 C (4) C41 C (4) C141 C (4) C41 C (4) C142 C (4) C42 C (4) C143 C (5) C43 C (5) C144 C (5) C44 C (5) C145 C (4) C45 C (4) C151 C (4) C51 C (4) C151 C (4) C51 C (4) C152 C (4) C52 C (4) C153 C (5) C53 C (4) C154 C (5) C54 C (4) C155 C (4) C55 C (4) Cl1 C1S 1.748(4) Ru2 P (7) Cl2 C1S 1.728(4) Table S33. Crystallographically determined bond angles for 3i. Atom Atom Atom Angle/ Atom Atom Atom Angle/ P1 1 Ru1 P (1) P3 Ru2 P (3) P2 Ru1 P (2) P3 2 Ru2 P (3) P2 1 Ru1 P (2) P3 2 Ru2 P (3) P2 1 Ru1 P (2) P3 Ru2 P (3) P2 Ru1 P (2) P4 Ru2 P (3) P2 1 Ru1 P (1) C101 2 Ru2 P (8) C1 Ru1 P (7) C101 Ru2 P (8) C1 1 Ru1 P (7) C101 2 Ru2 P (8) C1 Ru1 P (7) C101 Ru2 P (8) C1 1 Ru1 P (7) C101 Ru2 P (8) C1 1 Ru1 P (7) C101 2 Ru2 P (8) C1 Ru1 P (7) C101 Ru2 P (8) C1 Ru1 P (7) C101 2 Ru2 P (8) C1 1 Ru1 P (7) C101 2 Ru2 C (3) C1 Ru1 C C111 P3 Ru (9) C11 P1 Ru (8) C121 P3 Ru (10) C11 P1 C (12) C121 P3 C (13) C21 P1 Ru (9) C131 P3 Ru (9) C21 P1 C (12) C131 P3 C (13) 62

63 C21 P1 C (12) C131 P3 C (13) C31 P1 Ru (9) C112 P4 Ru (10) C12 P2 Ru (9) C141 P4 Ru (9) C41 P2 Ru (9) C141 P4 C (13) C41 P2 C (12) C151 P4 Ru (9) C51 P2 Ru (9) C151 P4 C (13) C51 P2 C (12) C151 P4 C (13) C51 P2 C (12) C102 C101 Ru (2) C2 C1 Ru (2) C101 C102 C (3) C1 C2 C (3) C104 C103 C (3) C4 C3 C (3) C104 C103 C (3) C4 C3 C (3) C108 C103 C (3) C8 C3 C (3) C105 C104 C (3) C5 C4 C (3) C104 C105 C (3) C4 C5 C (3) C105 C106 C (3) C5 C6 C (3) C107 C106 C (3) C5 C6 C (3) C107 C106 C (3) C7 C6 C (3) C108 C107 C (3) C8 C7 C (3) C107 C108 C (3) C7 C8 C (3) C110 C109 C (4) C10 C9 C (5) C112 C111 P (18) C12 C11 P (18) C111 C112 P (19) C11 C12 P (18) C122 C121 P (2) C22 C21 P (2) C122 C121 C (3) C22 C21 C (2) C126 C121 P (2) C26 C21 P (2) C121 C122 C (3) C23 C22 C (3) C124 C123 C (3) C24 C23 C (3) C123 C124 C (3) C23 C24 C (3) C126 C125 C (3) C24 C25 C (3) C125 C126 C (3) C25 C26 C (3) C132 C131 P (2) C32 C31 P (2) C132 C131 C (3) C36 C31 P (2) C136 C131 P (2) C36 C31 C (2) C131 C132 C (3) C33 C32 C (3) C134 C133 C (3) C34 C33 C (3) C133 C134 C (3) C35 C34 C (3) C136 C135 C (3) C34 C35 C (3) C135 C136 C (3) C35 C36 C (3) C142 C141 P (2) C42 C41 P (2) C142 C141 C (3) C46 C41 P (2) C146 C141 P (2) C46 C41 C (3) C141 C142 C (3) C43 C42 C (3) C144 C143 C (3) C44 C43 C (3) C143 C144 C (3) C45 C44 C (3) C144 C145 C (3) C44 C45 C (3) C145 C146 C (3) C41 C46 C (3) C152 C151 P (2) C52 C51 P (2) C156 C151 P (2) 63

64 C56 C51 P (2) C156 C151 C (3) C56 C51 C (2) C153 C152 C (3) C53 C52 C (3) C154 C153 C (3) C54 C53 C (3) C153 C154 C (3) C53 C54 C (3) C154 C155 C (3) C54 C55 C (3) C151 C156 C (3) C51 C56 C (3) Cl2 C1S Cl (2) P3 Ru2 P IR SPECTROELECTROCHEMICAL DATA Calculated (top) and experimental (bottom) IR spectrum in neutral state (black line) and first oxidized state (red dotted line) for 3f, 3h, 4a and 4b. (3f) trans-ru(c CC 6 H 4 C CSiMe 3-4) 2 (dppe) 2 64

65 (3h) trans-ru(c CC 6 H 4 NH 2-4) 2 (dppe) 2 : (4) trans-ru(c CC 6 H 4 C CSiMe 3-4)(C CC 6 H 4 NH 2-4)(dppe) 2 : 65

66 (5) trans-ru(c CC 6 H 4 CO 2 Me-4)(C CC 6 H 4 NH 2-4)(dppe) 2 : 66

67 Uv-Vis-NIR SPECTROELECTROCHEMICAL DATA (3f) trans-ru(c CC 6 H 4 C CSiMe 3-4) 2 (dppe) 2 : (3h) trans-ru(c CC 6 H 4 NH 2-4) 2 (dppe) 2 : 67

68 (4) trans-ru(c CC 6 H 4 C CSiMe 3-4)(C CC 6 H 4 NH 2-4)(dppe) 2 : (5) trans-ru(c CC 6 H 4 CO 2 Me-4)(C CC 6 H 4 NH 2-4)(dppe) 2 : 68

69 Table S32. Computed energy difference to the most stable rotamer (θ 0 Ω 0 ), ΔE, spin expectation value <S 2 >, characteristic vibrational frequencies ν, electronic excitation energies E trans below cm - 1 with corresponding transition dipole moment µ trans >1 D for [3f] +. a [3f] + in- plane perp out- of- plane θ 0 Ω 0 θ 0 Ω 90 θ 90 Ω 0 E [kj/mol] <S 2 > ν (C C) [cm - 1 ] 2180 (w) 2177 (w) 2034 (w) 2181 (w) 2178 (w) 2064 (w) ν (Ru- C C) [cm - 1 ] 1981 (vs) 1975 (vs) ν (C=C aryl ) [cm - 1 ] 1484 (w) 1596 (w) 1485 (w) E trans [cm - 1 ] (µ trans [D]) (9.7) (8.1) (0.6) orbital contribution 322 β =>323 β 321 β =>323 β 321 β =>323 β (1.9) 7312 (1.0) 319 β =>323 β 316 β =>323 β (10.3) 322 β =>323 β a Ground- state properties from TURBOMOLE 6.4, TDDFT excitations from Gaussian09. 69

70 Table S33. Orbital energies (E orb ) and Mulliken fragment spin- density (SD) contributions for the different conformations of [3f] +. in- plane- [3f] + (θ 0 Ω 0 ) perp- [3f] + (θ 0 Ω 90 ) E Orb Contribution [%] E Orb Contribution [%] MO [ev] Me 3 SiC C C C [Ru] C C C CC 6 H 4 [ev] Me 3 SiC C C C [Ru] C C C CC 6 H 4 C 6 H 4 SiMe 3 C 6 H 4 SiMe 3 SD / / β* * β* β β β Α β β

71 out- of- plane- [3f] + (θ 90 Ω 0 ) E Orb Contribution [%] MO [ev] Me 3 SiC C C 6 H 4 C C [Ru] C C C CC 6 H 4 SiMe 3 SD / β* * β* β β β β β

72 Figure S11. Computed potential energy surface [3h] + {in kj/mol; BLYP35/COSMO (CH 2 Cl 2 ) level} Table S34. Computed energy difference to the most stable rotamer (θ 0 Ω = 20 ), ΔE, spin expectation value <S 2 > and excitation energies E trans below cm -1 with corresponding transition dipole moment m trans >1 D for selected points on the PES of [3h] +. a [3h] + θ 0 Ω = 90 θ 90 Ω = 0 E [kj/mol] <S 2 > E trans [cm -1 ] (µ trans [D]) 9900 (10.0) 7849 (12.1) orbital contribution 277 β=>279 β 278 β=>279 β (1.3) (1.5) 275 β=>279 β 273 β=>279 β a Ground-state properties from TURBOMOLE 6.4, TDDFT excitations from Gaussian09. 72