Supporting Information for the Article Entitled

Supporting Information for the Article Entitled Catalytic Production of Isothiocyanates via a Mo(II) / Mo(IV) Cycle for the Soft Sulfur Oxidation of Isonitriles authored by Wesley S. Farrell, Peter Y. Zavalij, and Lawrence R. Sita* Department of Chemistry and Biochemistry University of Maryland, College Park, MD 20742 Crystallographic information for 1, 6, and 8. NMR spectral evidence demonstrating the (catalytic) activity of 1 3. Supporting spectra for thiosemicarbazides prepared via on-demand ITC synthesis. S1

NMR spectra Demonstrating the Generation of Compounds 1, 2, and 3. Figure S1. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the rapid conversion of 4 to 1 in the presence of excess methyl isocyanide. Labeled resonances are 4 (*), 1 (o), and methyl isocyanide (x). (Note: Reaction was nearly complete before the first NMR could be recorded). S2

Figure S2. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the conversion of 4 to 2 in the presence of excess tert-butyl isocyanide. Labeled resonances are 4 (*), 2 (o), and tert-butyl isocyanide (x). S3

Figure S3. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the conversion of 4 to 3 in the presence of excess 2,6-dimethylphenyl isocyanide. Labeled resonances are 4 (*), 3 (o), and 2,6-dimethylphenyl isocyanide (x). (Note: A second addition of 2,6-dimethylphenyl isocyanide was performed after recording the first NMR spectrum). S4

NMR Spectra Demonstrating the Generation Compounds 5, 6, and 7. 3.5 3.0 2.5 2.0 1.5 1.0 ppm 2.00 5.69 15.63 5.74 6.43 Figure S4. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the immediate conversion of 1 to 5 upon the addition of excess sulfur. S5

Figure S5. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the immediate conversion of 2 (generated in situ) to 6 upon the addition of excess sulfur. Labeled resonance is tert-butyl isocyanide (x), which overlaps with broad doublet of compound 6. S6

3.5 3.0 2.5 2.0 1.5 1.0 ppm 1.87 12.00 15.34 5.54 5.47 Figure S6. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the immediate conversion of 3 (generated in situ) to 7 upon the addition of excess sulfur. The unlabeled resonance at 2.1 ppm is excess 2,6-dimethylphenyl isocyanide (x). S7

NMR Spectra Demonstrating Catalytic Production of ITCs using Compounds 1, 2, and 3. Figure S7. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the generation of methyl isothiocyanate from S 8 and excess methyl isocyanide mediated by compound 1 after 0 h (bottom) and 3 d (top) at room temperature. Labeled resonances are methyl isocyanide (x) and methyl isothiocyanate (o). S8

Figure S8. Partial 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the generation of tert-butyl isothiocyanate from S 8 and excess tert-butyl isocyanide mediated by compound 2 after 0 h (bottom) and 4 d (top) at room temperature. Labeled resonances are tert-butyl isocyanide (x) and tert-butyl isothiocyanate (o). S9

Figure S9. 1 H NMR (400 MHz, benzene-d 6, 25 C) demonstrating the generation of 2,6-dimethylphenyl isothiocyanate from S 8 and excess 2,6-dimethylphenyl isocyanide mediated by compound 3 after 0 h (bottom) and 2 d (top) at 85 C. Labeled resonances are 2,6-dimethylphenyl isocyanide (x) and 2,6- dimethylphenyl isothiocyanate (o).. S10

Variable Temperature NMR Experiments Involving the Catalytic Formation of tert-butyl Isothiocyanate from tert-butyl Isocyanide and Sulfur Mediated by Compound 3. [SCNtBu] (M) 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 y = 0.000082x - 0.004550 R² = 0.982838 0 200 400 600 800 1000 1200 time (m) Figure S10. Representative plot of concentration of tert-butyl isothiocyanate versus time at 50 C catalyzed by compound 2. k (1/s) 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 y = 0.0025x - 0.7926 R² = 0.98496 0 320 325 330 335 340 345 350 355 T (K) Figure S11. Plot of initial rate constant (s -1 ) versus temperature (K) for the conversion of tert-butyl isocyanide to tert-butyl isothiocyanate catalyzed by 2. S11

1/T 0 0.0028 0.00285 0.0029 0.00295 0.003 0.00305 0.0031 0.00315-2 - 4 ln(k/t) - 6-8 y = - 8949.2x + 17.115 R² = 0.96344-10 - 12 Figure S12. Eyring plot for the conversion of tert-butyl isocyanide to tertbutyl isothiocyanate catalyzed by 2. S12

1.0 0.9 0.8 ppm Figure S13. Representative 1 H NMR (400 MHz, benzene-d 6, 50 C) spectra of the tert-butyl region during the catalytic generation of tert-butyl isothiocyanate from S 8 and tert-butyl isocyanide mediated by compound 2 (spectra recorded every 200 m). S13

Characterization of Thiosemicarbazides through On-Demand Generation of Isothiocyanates. 1-(p-tolylbenzoyl)-4-tert-butylthiosemicarbazide. Yield = 97%. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 1.45 (9H, s), 2.36 (3H, s), 3.34 (1H, br), 7.30 (2H, d, J = 8.0 Hz), 7.79 (2H, d, J = 8.0 Hz), 9.11 (1H, br), 10.23 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 20.9, 28.6, 52.6, 127.5, 128.8, 129.6, 141.8, 165.6, 181.3 (br). ESI-MS m/z: 266.10 (M+H). Figure S14. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-(p-tolylbenzoyl)-4-tertbutylthiosemicarbazide. * denotes ethyl acetate solvent impurity. o denoted H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S14

Figure S15. 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-(p-tolylbenzoyl)-4- tert-butylthiosemicarbazide. * denotes ethyl acetate solvent impurity. X denotes DMSO-d 6 solvent. 1-(p-methoxybenzoyl)-4-tert-butylthiosemicarbazide. Yield = 80%. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 1.45 (9H, s), 3.82 (3H, s), 7.02 (2H, d, J = 8.8 Hz), 7.87 (2H, d, J = 8.8 Hz), 9.09 (1H, br), 10.16 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 28.6, 52.6, 55.3, 113.6, 124.5, 129.4, 162.0, 165.2, 181.6 (br). ESI-MS m/z: 282.09 (M+H). S15

Figure S16. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-(p-methoxybenzoyl)-4- tert-butylthiosemicarbazide. * denotes ethyl acetate solvent impurity. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S16

Figure S17. 13 C( 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-(pmethoxybenzoyl)-4-tert-butylthiosemicarbazide. * denotes ethyl acetate solvent impurity. X denotes DMSO-d 6 solvent. 1-benzoyl-4-tert-butylthiosemicarbazide. Yield = 69%. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 1.45 (9H, s), 7.49 (2H, t, J = 7.7 Hz), 7.58 (1H, t, J = 7.5 Hz), 7.89 (2H, d, J = 7.5 Hz), 9.14 (1H, br), 10.30 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 28.6, 52.7, 127.5, 128.4, 131.8, 132.4, 165.7, 181.6. ESI-MS m/z: 252.12 (M+H). S17

Figure S18. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-benzoyl-4-tertbutylthiosemicarbazide. * denotes ethyl acetate solvent impurity. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. I denotes methyl substituted impurity present from using 1 as an isolated precatalyst in lieu of preparing 1 in situ. S18

Figure S19. 13 C{ 1 H} NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-benzoyl-4- tert-butylthiosemicarbazide. X denotes DMSO-d 6 solvent. 1-(p-tolylbenzoyl)-4-methylthiosemicarbazide. Yield = 96%. %. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 2.36 (3H, s). 2.87 (3H, d, J = 4.4 Hz), 7.29 (2H, d, J = 8.3 Hz), 7.81 (2H, d, J = 8.3 Hz), 8.02 (1H, br d), 9.29 (1H, br), 10.25 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 20.8, 30.8, 127.6, 128.5, 129.6, 141.6, 165.8, 182.5. ESI-MS m/z: 224.02 (M+H). S19

Figure S20. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-(p-tolylbenzoyl)-4- methylthiosemicarbazide. * denotes ethyl acetate solvent impurity. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S20

Figure S21. 13 C( 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-(p-tolylbenzoyl)-4- methylthiosemicarbazide. * denotes ethyl acetate solvent impurity. X denotes DMSO-d 6 solvent. 1-(p-methoxybenzoyl)-4-methylthiosemicarbazide. Yield = 82%. %. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 2.86 (3H, d, J = 4.4 Hz), 3.82 (3H, s), 7.02 (2H, d, J = 8.9 Hz), 7.89 (2H, d, J = 8.9 Hz), 8.02 (1H, br d, J = 4.4 Hz), 9.27 (1H, br), 10.19 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 30.8, 55.3, 133.4, 124.6, 129.6, 162.0, 135.4, 182.4. S21

Figure S22. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-(p-methoxybenzoyl)-4- methylthiosemicarbazide. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S22

Figure S23. 13 C( 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-(pmethoxybenzoyl)-4-methylthiosemicarbazide. X denotes DMSO-d 6 solvent. 1-benzoyl-4-methylthiosemicarbazide. Yield = 76%. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 2.87 (3H, d, J = 4.3 Hz), 7.49 (2H, t, J = 7.8 Hz), 7.58 (1H, t, J = 7.4 Hz), 7.92 (2H, d, J = 7.8 Hz), 8.05 (1H, br d, J = 4.3 Hz), 9.33 (1H, br), 10.33 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 30.9, 127.7, 128.2, 131.7, 132.4, 165.9. ESI-MS m/z: 210.09 (M+H). S23

Figure S24. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-(p-tolylbenzoyl)-4- methylthiosemicarbazide. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S24

Figure S25. 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-benzoyl-4- methylthiosemicarbazide. X denotes DMSO-d 6 solvent. (Note: C b cannot be seen due to the broadness of the signal). 1-(p-tolylbenzoyl)-4-(2,6-dimethylphenyl)thiosemicarbazide. Yield = 95%. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 2.15 (6H, s), 2.36 (3H, s), 7.04 (3H, m), 7.29 (2H, d, J = 8.1 Hz), 7.86 (2H, d, J = 8.1), 9.39 (1H, br), 9.53 (1H, br), 10.47 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 17.9, 20.9, 126.5, 127.3, 127.9, 128.5, 129.9, 136.5, 137.0, 141.5, 166.1, 181.5. ESI-MS m/z: 314.06 (M+H). S25

Figure S26. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-(p-tolylbenzoyl)-4-(2,6- dimethylphenyl)thiosemicarbazide. * denotes ethyl acetate solvent impurity. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S26

Figure S27. 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-(p-tolylbenzoyl)-4- (2,6-dimethylphenyl)thiosemicarbazide. X denotes DMSO-d 6 solvent. * denotes ethyl acetate solvent impurity. 1-(p-methoxybenzoyl)-4-(2,6-dimethylphenyl)thiosemicarbazide. Yield = 91%. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 2.16 (6H, s), 3.81 (3H, s), 7.05 (5H, m), 7.94 (2H, d, J = 8.6 Hz), 9.40 (1H, br), 9.51 (1H, br), 10.43 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ):17.9, 55.4, 113.3, 124.9, 126.6, 127.3, 129.9, 136.5, 137.0, 161.9, 165.7, 181.5. ESI-MS m/z: 330.05 (M+H). S27

Figure S28. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-(p-methoxybenzoyl)-4- (2,6-dimethylphenyl)thiosemicarbazide. * denotes ethyl acetate solvent impurity. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S28

Figure S29. 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-(pmethoxybenzoyl)-4-(2,6-dimethylphenyl)thiosemicarbazide. * denotes ethyl acetate solvent impurity. X denotes DMSO-d 6 solvent. 1-benzoyl-4-(2,6-dimethylphenyl)thiosemicarbazide.Yield = 88%. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ): 2.17 (6H, s), 7.05 (3H, m), 7.49 (2H, t, J = 7.4 Hz), 7.57 (1H, t, J = 7.4 Hz), 7.97 (2H, d, J = 7.4 Hz), 9.42 (1H, br), 9.58 (1H, br), 10.56 (1H, br). 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ): 17.9, 126.6, 127.3, 127.9, 128.0, 131.6, 132.7, 136.5, 137.0, 166.1, 181.5. ESI-MS m/z: 300.11 (M+H). S29

Figure S30. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of 1-benzoyl-4-(2,6- dimethylphenyl)thiosemicarbazide. * denotes ethyl acetate solvent impurity. o denotes H 2 O solvent impurity. X denotes DMSO-d 6 solvent. S30

Figure S31. 13 C{ 1 H} NMR (125 MHz, 25 C, DMSO-d 6 ) of 1-benzoyl -4-(2,6- dimethylphenyl)thiosemicarbazide. * denotes ethyl acetate solvent impurity. X denotes DMSO-d 6 solvent. Control Experiments For On-Demand Isothiocyanate Synthesis A representative procedure is given. A solution of S 8 (0.063 g, 0.246 mmol), methyl isocyanide (15 μl, 0.250 mmol) and p-tolylbenzhydrazide (0.038 g, 0.252 mmol) in 5 ml THF was prepared and heated to 70 C for 16 h. Volatiles were removed in vacuo to furnish a yellow solid, and the crude reaction mixture was analyzed by 1 H NMR, revealing unreacted p-tolylbenzhydrazide as the only species present. S31

Figure S32. 1 H NMR (400 MHz, 25 C, DMSO-d 6 ) of a) crude reaction mixture obtained from heating of methyl isocyanide, S 8, and p-tolylbenzhydrazide in THF for 16 h, and b) pure p-tolylbenzhydrazide. X denotes DMSO-d 6 solvent. o denotes H 2 O solvent impurity. References 1. R. E. Schuster, J. E. Scott, J. Casanova, Org. Synth. 1966, 46, 75. 2. W. S. Farrell, P. Y. Zavalij, L. R. Sita, Angew. Chem. Int. Ed. 2015, 54, 4269-4273. S32

Crystallographic Information Cp*Mo[N( i Pr)C(Ph)N( i Pr)](CNCH 3 ) 2 (1) Figure S33. Crystal structure of 1 with hydrogen atoms omitted for clarity, ellipsoids for the non-hydrogen atoms are shown at the 30% probability level. A red plate-like specimen of C 27 H 40 MoN 4, approximate dimensions 0.04 mm 0.17 mm 0.21 mm, was used for the X-ray crystallographic analysis. The X- ray intensity data were measured on a Bruker APEX-II CCD system equipped with a graphite monochromator and a MoKα sealed tube (λ = 0.71073 Å). Data collection temperature was 150 K. The total exposure time was 37.87 hours. The frames were integrated with the Bruker SAINT software package using a narrow-frame algorithm. The integration of the data using a triclinic unit cell yielded a total of 22479 reflections to a maximum θ angle of 30.00 (0.71 Å resolution), of which 7694 were independent (average redundancy 2.922, completeness = 99.3%, R int = 3.00%) and6680 (86.82%) were greater than 2σ(F 2 ). The final cell constants of a = 10.2352(11) Å, b = 10.2372(11) Å, c = 13.6813(15) Å, α = 71.9970(17), β = 88.2157(18), γ = 77.0921(17), V =1327.8(2) Å 3, are based upon the refinement of the XYZ-centroids of 8177 reflections above 20 σ(i) with 4.462 < S33

2θ < 61.96. Data were corrected for absorption effects using the multi-scan method (SADABS). The calculated minimum and maximum transmission coefficients (based on crystal size) are 0.8910 and 0.9800. The structure was solved and refined using the Bruker SHELXTL Software Package, using the space group P-1, with Z = 2 for the formula unit, C 27 H 40 MoN 4. The final anisotropic full-matrix least-squares refinement on F 2 with 331 variables converged at R 1 = 3.25%, for the observed data and wr 2 = 6.35% for all data. The goodness-of-fit was 1.000. The largest peak in the final difference electron density synthesis was 0.644 e - /Å 3 and the largest hole was -0.632 e - /Å 3 with an RMS deviation of 0.067 e - /Å 3. On the basis of the final model, the calculated density was 1.292g/cm 3 and F(000), 544 e -. APEX2 Version 2010.11-3 (Bruker AXS Inc.) SAINT Version 7.68A (Bruker AXS Inc., 2009) SADABS Version 2008/1 (G. M. Sheldrick, Bruker AXS Inc.) XPREP Version 2008/2 (G. M. Sheldrick, Bruker AXS Inc.) XS Version 2008/1 (G. M. Sheldrick, Acta Cryst. (2008). A64, 112-122) XL Version 2012/4 (G. M. Sheldrick, (2012) University of Gottingen, Germany) Platon (A. L. Spek, Acta Cryst. (1990). A46, C-34) Table S1. Sample and crystal data for 1. Identification code 2522 Chemical formula C 27 H 40 MoN 4 Formula weight 516.57 Temperature 150(2) K Wavelength 0.71073 Å Crystal size 0.04 0.17 0.21 mm Crystal habit red plate Crystal system triclinic Space group P-1 Unit cell dimensions a = 10.2352(11) Å α = 71.9970(17) b = 10.2372(11) Å β = 88.2157(18) c = 13.6813(15) Å γ = 77.0921(17) Volume 1327.8(2) Å 3 Z 2 Density (calculated) 1.292 Mg/cm 3 Absorption coefficient 0.514 mm -1 F(000) 544 Table S2. Data collection and structure refinement for 1. S34

Diffractometer Bruker APEX-II CCD Radiation source sealed tube, MoKα Theta range for data collection 2.04 to 30.00 Index ranges -14 h 14, -14 k 14, -19 l 19 Reflections collected 22479 Independent reflections 7694 [R(int) = 0.0300] Coverage of independent 99.3% reflections Absorption correction multi-scan Max. and min. transmission 0.9800 and 0.8910 Structure solution technique direct methods Structure solution program ShelXS-97 (Sheldrick, 2008) Refinement method Full-matrix least-squares on F 2 Refinement program ShelXL-2012 (Sheldrick, 2012) Function minimized Σ w(f 2 o - F 2 c ) 2 Data / restraints / parameters 7694 / 121 / 331 Goodness-of-fit on F 2 1.000 Δ/σ max 0.001 Final R indices 6680 data; I>2σ(I) R 1 = 0.0325, wr 2 = 0.0606 all data R 1 = 0.0415, wr 2 = 0.0635 Weighting scheme w=1/[σ 2 (F 2 o )+(0.0100P) 2 +1.1570P], P=(F 2 o +2F 2 c )/3 Largest diff. peak and hole 0.644 and -0.632 eå -3 R.M.S. deviation from mean 0.067 eå -3 R int = Σ F o 2 - F o 2 (mean) / Σ[F o 2 ] R 1 = Σ F o - F c / Σ F o S35

GOOF = S = {Σ[w(F o 2 - F c 2 ) 2 ] / (n - p)} 1/2 wr 2 = {Σ[w(F o 2 - F c 2 ) 2 ] / Σ[w(F o 2 ) 2 ]} 1/2 Cp*Mo[N( i Pr)C(Ph)N( i Pr)](CN t Bu)(η 2 -SCN t Bu) (6) Figure S34. Crystal structure of 6 with hydrogen atoms omitted for clarity, ellipsoids for the non-hydrogen atoms are shown at the 30% probability level. A orange prism-like specimen of C 33 H 52 MoN 4 S, approximate dimensions 0.09 mm &#215 0.24 mm &#215 0.26 mm, was used for the X-ray crystallographic analysis. The X-ray intensity data were measured on a Bruker APEX-II CCD system equipped with a graphite monochromator and a MoKα sealed tube (λ = 0.71073 Å). Data collection temperature was 150 K. S36

The total exposure time was 15.25 hours. The frames were integrated with the Bruker SAINT software package using a narrow-frame algorithm. The integration of the data using a monoclinic unit cell yielded a total of 36576 reflections to a maximum θ angle of 30.00 (0.71 Å resolution), of which9950 were independent (average redundancy 3.676, completeness = 99.6%, R int = 2.84%) and 8565 (86.08%) were greater than 2σ(F 2 ). The final cell constants of a = 9.1377(11) Å, b = 36.625(5) Å, c = 10.7554(13) Å, β = 107.909(2), V = 3425.1(7) Å 3, are based upon the refinement of the XYZcentroids of 9913 reflections above 20 σ(i) with 4.448 < 2θ < 62.28. Data were corrected for absorption effects using the multi-scan method (SADABS). The calculated minimum and maximum transmission coefficients (based on crystal size) are 0.8760 and 0.9590. The structure was solved and refined using the Bruker SHELXTL Software Package, using the space group P2 1 /n, with Z = 4 for the formula unit, C 33 H 52 MoN 4 S. The final anisotropic full-matrix least-squares refinement on F 2 with 426 variables converged at R 1 = 3.77%, for the observed data and wr 2 = 7.48% for all data. The goodness-of-fit was 1.000. The largest peak in the final difference electron density synthesis was 0.883 e - /Å 3 and the largest hole was -0.651 e - /Å 3 with an RMS deviation of 0.062 e - /Å 3. On the basis of the final model, the calculated density was 1.227 g/cm 3 and F(000), 1344 e -. APEX2 Version 2010.11-3 (Bruker AXS Inc.) SAINT Version 7.68A (Bruker AXS Inc., 2009) SADABS Version 2008/1 (G. M. Sheldrick, Bruker AXS Inc.) XPREP Version 2008/2 (G. M. Sheldrick, Bruker AXS Inc.) XS Version 2008/1 (G. M. Sheldrick, Acta Cryst. (2008). A64, 112-122) XL Version 2012/4 (G. M. Sheldrick, (2012) University of Gottingen, Germany) Platon (A. L. Spek, Acta Cryst. (1990). A46, C-34) Table S2. Sample and crystal data for 6. Identification code 2530 Chemical formula C 33 H 52 MoN 4 S Formula weight 632.78 Temperature 150(2) K Wavelength 0.71073 Å Crystal size 0.09 &#215 0.24 &#215 0.26 mm Crystal habit orange prism Crystal system monoclinic Space group P2 1 /n Unit cell dimensions a = 9.1377(11) Å α = 90 b = 36.625(5) Å β = 107.909(2) c = 10.7554(13) Å γ = 90 Volume 3425.1(7) Å 3 S37

Z 4 Density (calculated) 1.227 Mg/cm 3 Absorption coefficient 0.470 mm -1 F(000) 1344 Table S10. Data collection and structure refinement for 6. Diffractometer Bruker APEX-II CCD Radiation source sealed tube, MoKα Theta range for data collection 2.07 to 30.00 Index ranges -12 &#8804 h &#8804 12, -51 &#8804 k &#8804 51, -15 &#8804 l &#8804 15 Reflections collected 36576 Independent reflections 9950 [R(int) = 0.0284] Coverage of independent 99.6% reflections Absorption correction multi-scan Max. and min. transmission 0.9590 and 0.8760 Structure solution direct methods technique Structure ShelXS-97 (Sheldrick, 2008) solution program Refinement method Full-matrix least-squares on F 2 Refinement program ShelXL-2012 (Sheldrick, 2012) Function minimized Σ w(f 2 o - F 2 c ) 2 Data / restraints / 9950 / 216 / 426 parameters Goodness-of-fit on F 2 1.000 Δ/σ max 0.001 Final R indices 8565 data; I>2σ(I) R 1 = 0.0377, wr 2 = S38

Weighting scheme Largest diff. peak and hole R.M.S. deviation from mean 0.0714 R all data 1 = 0.0467, wr 2 = 0.0748 w=1/[σ 2 (F 2 o )+(0.0100P) 2 +4.6350P], P=(F 2 o +2F 2 c )/3 0.883 and -0.651 eå -3 0.062 eå -3 R int = Σ F o 2 - F o 2 (mean) / Σ[F o 2 ] R 1 = Σ F o - F c / Σ F o GOOF = S = {Σ[w(F o 2 - F c 2 ) 2 ] / (n - p)} 1/2 wr 2 = {Σ[w(F o 2 - F c 2 ) 2 ] / Σ[w(F o 2 ) 2 ]} 1/2 Cp*Mo[N( i Pr)C(Ph)N( i Pr)](κ-(S,S)-S 2 CN t Bu) (8) Figure S35. Crystal structure of 8 with hydrogen atoms omitted for clarity, ellipsoids for the non-hydrogen atoms are shown at the 30% probability level. A orange prism-like specimen of C 29.50 H 46.75 MoN 3 O 0.38 S 2, approximate dimensions 0.14 mm &#215 0.50 mm &#215 0.51 mm, was used for the X-ray crystallographic analysis. The X-ray intensity data were measured on a Bruker S39

APEX-II CCD system equipped with a graphite monochromator and a MoKα sealed tube (λ = 0.71073 Å). Data collection temperature was 150 K. The total exposure time was 4.04 hours. The frames were integrated with the Bruker SAINT software package using a narrow-frame algorithm. The integration of the data using a monoclinic unit cell yielded a total of 51812 reflections to a maximum θ angle of 30.00 (0.71 Å resolution), of which 9155were independent (average redundancy 5.659, completeness = 100.0%, R int = 2.20%) and 8447 (92.27%) were greater than 2σ(F 2 ). The final cell constants of a = 9.1512(9) Å, b = 18.9957(19) Å, c = 18.5700(18) Å, β = 103.4042(14), V = 3140.2(5) Å 3, are based upon the refinement of the XYZcentroids of 9946 reflections above 20 σ(i) with 4.993 < 2θ < 61.17. Data were corrected for absorption effects using the multi-scan method (SADABS). The calculated minimum and maximum transmission coefficients (based on crystal size) are 0.7550 and 0.9230. The structure was solved and refined using the Bruker SHELXTL Software Package, using the space group P2 1 /n, with Z = 4 for the formula unit, C 29.50 H 46.75 MoN 3 O 0.38 S 2. The final anisotropic fullmatrix least-squares refinement on F 2 with 319 variables converged at R 1 = 2.04%, for the observed data and wr 2 = 4.62% for all data. The goodnessof-fit was 1.001. The largest peak in the final difference electron density synthesis was 0.452 e - /Å 3 and the largest hole was -0.512 e - /Å 3 with an RMS deviation of 0.049 e - /Å 3. On the basis of the final model, the calculated density was 1.289 g/cm 3 and F(000), 1287 e -. APEX2 Version 2010.11-3 (Bruker AXS Inc.) SAINT Version 7.68A (Bruker AXS Inc., 2009) SADABS Version 2008/1 (G. M. Sheldrick, Bruker AXS Inc.) XPREP Version 2008/2 (G. M. Sheldrick, Bruker AXS Inc.) XS Version 2008/1 (G. M. Sheldrick, Acta Cryst. (2008). A64, 112-122) XL Version 2012/4 (G. M. Sheldrick, (2012) University of Gottingen, Germany) Platon (A. L. Spek, Acta Cryst. (1990). A46, C-34) Table S3. Sample and crystal data for 8. Identification code 2480 Chemical formula C 29.50 H 46.75 MoN 3 O 0.38 S 2 Formula weight 609.51 Temperature Wavelength Crystal size Crystal habit Crystal system 150(2) K 0.71073 Å 0.14 &#215 0.50 &#215 0.51 mm orange prism monoclinic Space group P2 1 /n S40

Unit cell dimensions a = 9.1512(9) Å α = 90 b = 18.9957(19) Å β = 103.4042(14) c = 18.5700(18) Å γ = 90 Volume 3140.2(5) Å 3 Z 4 Density (calculated) 1.289 Mg/cm 3 Absorption coefficient 0.574 mm -1 F(000) 1287 Table S3. Data collection and structure refinement for 8. Diffractometer Radiation source Theta range for data collection Index ranges Reflections collected 51812 Bruker APEX-II CCD sealed tube, MoKα 2.14 to 30.00 Independent reflections 9155 [R(int) = 0.0220] Coverage of independent reflections 100.0% Absorption correction Max. and min. transmission Structure solution technique Structure solution program -12 &#8804 h &#8804 12, -26 &#8804 k &#8804 26, -26 &#8804 l &#8804 26 multi-scan 0.9230 and 0.7550 direct methods ShelXS-97 (Sheldrick, 2008) Refinement method Full-matrix least-squares on F 2 Refinement program ShelXL-2012 (Sheldrick, 2012) Function minimized Σ w(f o 2 - F c 2 ) 2 Data / restraints / parameters Goodness-of-fit on F 2 1.001 Δ/σ max 0.001 9155 / 0 / 319 Final R indices 8447 data; I>2σ(I) R 1 = 0.0204, wr 2 = 0.0453 all data R 1 = 0.0227, wr 2 = 0.0462 Weighting scheme w=1/[σ 2 (F o 2 )+(0.0100P) 2 +2.2020P], P=(F o 2 +2F c 2 )/3 Largest diff. peak and hole R.M.S. deviation from mean 0.452 and -0.512 eå -3 0.049 eå -3 R int = Σ F o 2 - F o2 (mean) / Σ[F o2 ] R 1 = Σ F o - F c / Σ F o S41

GOOF = S = {Σ[w(F o 2 - F c 2 ) 2 ] / (n - p)} 1/2 wr 2 = {Σ[w(F o 2 - F c 2 ) 2 ] / Σ[w(F o 2 )2 ]} 1/2 S42