1. Outline Slide 1 Lecture 1 - Redox-Active Ligands: What Are They? How Do They Work? and How Might They Be Improved? Lecture 2 - The Development of a Highly Active Manganese Hydrosilylation Catalyst Lecture 3 - Hydrosilylation and Beyond: Expanding the Scope of Redox- Active Ligand Assisted Catalysts

2. Reduction of CO 2 to Methanol? Slide 2

3. Reduction of CO 2 to Methanol? Slide 3

4. Reduction of CO 2 to Methanol? Slide 4

5. Reductive CO 2 Coupling Slide 5 Tufan Mukhopadhyay Bright Blue

6. Reductive CO 2 Coupling Slide 6 Tufan Mukhopadhyay No evidence for catalytic CO 2 reduction Bright Blue

7. Oxidation of Mn Precursors Slide 7 Tufan Mukhopadhyay Bright Blue

8. Oxidation of Mn Precursors Slide 8 Tufan Mukhopadhyay Bright Blue

9. Oxidation of Mn Precursors Slide 9 Tufan Mukhopadhyay Will Oxidized Complexes Perform as Water Oxidation Catalysts? Currently Working to Prepare Neutral and Cationic Mn x (OAc) y Complexes Bright Blue

10. How About Iron? Slide 10 Tufan Mukhopadhyay / Chandrani Ghosh - Bright Purple - Diamagnetic - 31 P NMR: 31.47 (s, Fe-P)

11. How About Iron? Slide 11 Tufan Mukhopadhyay / Chandrani Ghosh - Bright Purple - Diamagnetic - 31 P NMR: 31.47 (s, Fe-P) - κ 5 -PDI Coordination Verified by XRD - Diamagnetic - 31 P NMR: 69.80 (s, Fe-P) - Inactive for Hydrosilylation E 1 1/2 = -0.50 V (rev) and E 2 1/2 = 0.08 V (irr) (vs. Fc/Fc + in THF)

12. H + Reduction Catalyst? Slide 12 Chandrani Ghosh - Dark Green - Diamagnetic - 31 P NMR: 56.96 (s, Fe-P)

13. H + Reduction Catalyst? Slide 13 Chandrani Ghosh - Dark Green - Diamagnetic - 31 P NMR: 56.96 (s, Fe-P) - Benzene Insoluble - Diamagnetic - 31 P NMR: 32.29 (s, Fe-P) - Addition of Excess HBF 4 does not Result in Decomposition

14. An Iron Hydrosilylation Precatalyst Slide 14 Raja Pal - Dark Blue - Diamagnetic

15. ( PyEt PDI)Fe Mediated Ketone Hydrosilylation Slide 15 Raja Pal SubstrateTemperature% Conv.TimeTOF (h -1 ) 25 °C>991 h10 25 °C>991 h10 80 °C4513 h<1

16. ( PyEt PDI)Fe Mediated Alkyne Hydrosilylation Slide 16 Raja Pal SubstrateTemperature% Conv.TimeTOF (h -1 ) 65 °C>9925 min24 65 °C9110 h<1 85 °C445 h<1 Poor activity, but capable of catalyzing ketone and alkene reduction

17. Moving Across the First Row  Co Slide 17 Raja Pal - Greenish-Blue - Diamagnetic - L/R Ligand Inequiv.

18. Moving Across the First Row  Co Slide 18 Raja Pal - Greenish-Blue - Diamagnetic - L/R Ligand Inequiv.

19. Confirming Chemical Chelate Activity Slide 19 Raja Pal

20. Hydrosilylation Activity Slide 20 Raja Pal SubstrateTemperature% Conv.TimeTOF (h -1 ) 25 °C>9940 min28 25 °C6040 min18 Mechanism remains under investigation, likely to proceed following deinsertion

21. A Second Ligand Framework Slide 21 Tyler Porter - Easy to Prepare - Highly Modular

22. A Second Ligand Framework Slide 22 Tyler Porter Muresan, N.; Chlopek, K.; Weyhermüller, T.; Nesse, F.; Wieghardt, K. Inorg. Chem. 2007, 46, 5327. - Easy to Prepare - Highly Modular Neutral Radical MonoanionDianion 1.29 Å 1.47 Å 1.34 Å 1.38 Å 1.40 Å 1.36 Å

23. Continuing with Cobalt Slide 23 Hagit Ben-Daat 1 H NMR (benzene-d 6, ppm): -19.82 (dd, 90 Hz, 39 Hz, Co-H) 31 P NMR (benzene-d 6, ppm): 76.08, 51.33

24. Catalytic Activity Slide 24 Hagit Ben-Daat SubstrateTemperature% Conv.TimeTOF (h -1 ) 25 °C>996 h16 25 °C>991 h99 Unoptimized, promising activitiy for terminal alkynes at 1 mol% catalyst loading

25. Moving Across the First Row  Ni Slide 25 Tyler Porter - Could Not Isolate κ 4 -DI Complex - For ( PyEt DI)Ni: E 1 1/2 = -0.84 V and E 2 1/2 = -0.56 V (vs. Fc/Fc + in THF ) Muresan, N.; Chlopek, K.; Weyhermüller, T.; Nesse, F.; Wieghardt, K. Inorg. Chem. 2007, 46, 5327.

26. Bis(ligand)Ni Complexes Slide 26 Tyler Porter Dihedral Angle: 74.8° - Could Not Isolate κ 4 -DI Complex - For ( PyEt DI)Ni: E 1 1/2 = -0.84 V and E 2 1/2 = -0.56 V (vs. Fc/Fc + in THF ) Muresan, N.; Chlopek, K.; Weyhermüller, T.; Nesse, F.; Wieghardt, K. Inorg. Chem. 2007, 46, 5327.

27. Bis(ligand)Ni Complexes Slide 27 Tyler Porter Dihedral Angle: 74.8° Radical Monoanion 1.34 Å 1.38 Å - Could Not Isolate κ 4 -DI Complex - For ( PyEt DI)Ni: E 1 1/2 = -0.84 V and E 2 1/2 = -0.56 V (vs. Fc/Fc + in THF ) - High-Spin Ni(II) Center Antiferromagnetically Coupled to Two DI Radical Monoanions Muresan, N.; Chlopek, K.; Weyhermüller, T.; Nesse, F.; Wieghardt, K. Inorg. Chem. 2007, 46, 5327.

28. ( κ 4 -DI)Ni Complex Preparation Slide 28 Tyler Porter - Green Solution - E 1 1/2 = -0.54 V and E 2 1/2 = -0.13 V (vs. Fc/Fc + in ACN) - 1 H NMR: Methylene H’s Equiv. - 31 P NMR: 56.36 ppm (s)

29. ( κ 4 -DI)Ni Complex Preparation Slide 29 Tyler Porter - Green Solution - E 1 1/2 = -0.54 V and E 2 1/2 = -0.13 V (vs. Fc/Fc + in ACN) - 1 H NMR: Methylene H’s Equiv. - 31 P NMR: 56.36 ppm (s) - Red Solution - E 1 1/2 = -0.46 V and E 2 1/2 = 0.21 V (vs. Fc/Fc + in ACN) - 1 H NMR: Methylene H’s Inequiv. - 31 P NMR: 39.03 ppm (s) Both Complexes are Diamagnetic

30. ( κ 4 -DI)Ni Structural Parameters Slide 30 Tyler Porter Dihedral Angle 32.5°56.3°

31. ( κ 4 -DI)Ni Structural Parameters Slide 31 Tyler Porter Radical Monoanion? 1.34 Å 1.38 Å 1.34 Å 1.38 Å Dihedral Angle 32.5°56.3° Radical Monoanion?

32. DFT Analysis of ( Ph 2 PPr DI)Ni Slide 32 Tyler Porter 0.456 0.022 -0.225 0.019 -0.142 -0.138 Broken Symmetry (1,1) S = 0.81 Mulliken Spin Population

33. DFT Analysis of ( Ph 2 PPr DI)Ni Slide 33 Tyler Porter 0.456 0.022 -0.225 0.019 -0.142 -0.138 Broken Symmetry (1,1) S = 0.81 Mulliken Spin Population Ni(I) Center Antiferromagnetically Coupled to a DI Radical Monoanion

34. DFT Analysis of ( Ph 2 PEt DI)Ni Slide 34 Tyler Porter Closed Shell (S = 0.9975) Ni(0) Center Coordinated to a Neutral DI Ligand Very Surprising!

35. DFT Analysis of ( Ph 2 PEt DI)Ni Slide 35 Tyler Porter Closed Shell (S = 0.9975) Ni(0) Center Coordinated to a Neutral DI Ligand Very Surprising! Due to Covalency! UV-Vis: ( Ph 2 PEt DI)Ni – 420 nm (ε = 5,600 M -1 cm -1 ) 714 nm (ε = 5,000 M -1 cm -1 ) ( Ph 2 PEt DI)Ni – 498 nm (ε = 11,800 M -1 cm -1 ) 714 nm (ε = 1,000 M -1 cm -1 )

36. ( κ 4 -DI)Ni Catalytic Activity Slide 36 Tyler Porter SubstrateCatalystProduct (Ratio)% Conv.Time ( Ph 2 PEt DI)Ni PhSiH(OCy) 2 PhSiH 2 (OCy) (20:1) 9324 h ( Ph 2 PPr DI)Ni PhSiH(OCy) 2 PhSiH 2 (OCy) (1:2) >9924 h ( Ph 2 PEt DI)Ni PhSiH(OCH( i Pr) 2 ) 2 PhSiH 2 (OCH( i Pr) 2 ) (11:1) >9924 h ( Ph 2 PPr DI)Ni PhSiH(OCH( i Pr) 2 ) 2 PhSiH 2 (OCH( i Pr) 2 ) (1:1) >9924 h Both Catalysts Hydrosilylate Phenylacetylene

37. N 2 Reduction Slide 37 Haber-Bosch Process (1909) 145 M tons NH 3 produced/yr 80% towards fertilizer, sustains 40% of world’s population Conducted between 100-250 atm and 300-450 ˚C >1% of world’s annual energy consumption Catalyzed by magnetite (Fe 3 O 4 ) fused with 2-4% Al 2 O 3, 2-4% CaO, 0.5-1.2% K 2 O, 0-1% MgO Catalyst reduction affords low-valent Fe sites that achieve N≡N cleavage

38. N 2 Reduction Slide 38 Haber-Bosch Process (1909) 145 M tons NH 3 produced/yr 80% towards fertilizer, sustains 40% of world’s population Conducted between 100-250 atm and 300-450 ˚C >1% of world’s annual energy consumption Catalyzed by magnetite (Fe 3 O 4 ) fused with 2-4% Al 2 O 3, 2-4% CaO, 0.5-1.2% K 2 O, 0-1% MgO Catalyst reduction affords low-valent Fe sites that achieve N≡N cleavage Can Ammonia Synthesis be Conducted Under Mild Conditions Using a Well-Defined Transition Metal Catalyst?

39. Mo Catalysts for N 2 Reduction Slide 39 Raja Pal - (cis- κ 2 -P,P- Ph 2 PPr PDI)Mo(CO) 4 Formed at Lower Temperatures - IR (benzene): 1740 cm -1 - 13 C NMR: 272.16 ppm (t, 20 Hz) - 31 P NMR: 34.86 ppm (s)

40. Mo Catalysts for N 2 Reduction Slide 40 Raja Pal - IR (benzene): 1740 cm -1 - IR (KBr): 1826 cm -1 - 13 C NMR: 214.23 ppm (m) - 31 P NMR: 37.70 ppm (d, 14 Hz), 37.48 ppm (d, 14 Hz)

41. Mo Catalysts for N 2 Reduction Slide 41 Raja Pal - 31 P NMR: 7.90 ppm (s)- IR (benzene): 1740 cm -1 - IR (KBr): 1826 cm -1 - 13 C NMR: 214.23 ppm (m) - 31 P NMR: 37.70 ppm (d, 14 Hz), 37.48 ppm (d, 14 Hz)

42. Mo Catalysts for N 2 Reduction Slide 42 Raja Pal

43. Mo Catalysts for N 2 Reduction Slide 43 Raja Pal

44. Mo Catalysts for N 2 Reduction Slide 44 Raja Pal - IR (benzene): 1994, 1904 cm -1 - 31 P NMR: 57.20 ppm (d, 96 Hz), 46.20 ppm (d, 96 Hz)

45. Mo Catalysts for N 2 Reduction Slide 45 Raja Pal - IR (benzene): 1994, 1904 cm -1 - 31 P NMR: 57.20 ppm (d, 96 Hz), 46.20 ppm (d, 96 Hz) - 31 P NMR: 2.30 ppm (s) Protonation to Form NH 3 Will be Investigated

46. Take Home Messages Slide 46 - Developed a Highly Active Mn Catalyst by Modifying Chelate Denticity TOF = 14,850 h -1

47. Take Home Messages Slide 47 - Developed a Highly Active Mn Catalyst by Modifying Chelate Denticity - Radical Chemistry Not Completely Prevented TOF = 14,850 h -1

48. Take Home Messages Slide 48 - Developed a Highly Active Mn Catalyst by Modifying Chelate Denticity - Radical Chemistry Not Completely Prevented - Only the Beginning TOF = 14,850 h -1

49. Acknowledgements Arizona State University - Tufan K. Mukhopadhyay - Raja Pal - Hagit Ben-Daat - Tyler M. Porter - Chandrani Ghosh - Christopher L. Rock - Nick MacLean - Thomas L. Groy - Marco Flores Los Alamos National Laboratory - John C. Gordon - Nathan C. Smythe Slide 49 Funding

50. Slide 50