1. Natural Gas: An Alternative to Petroleum? Crabtree, R. H. Chem. Rev. 1995, 95, 987-1007 American Methanol Institute, 2000 Natural gas reserves: ~ 60 years Petroleum reserves: ~ 40 years   Combustion of natural gas releases more energy per gram than that of petroleum   Combustion of natural gas releases more energy per CO 2 molecule than that of petroleum   Approximately twice the amount of natural gas produced for consumption is vented or burned at its source   Pressurization and refrigeration required for liquefaction (bp -164 °C)   Largest reserves located in remote regions of the world  

2. Natural Gas is a Source of Methane

3. Limitations for the Practical Use of Methane Crabtree, R. H. Chem. Rev. 1995, 95, 987-1007

4. Methanol: a Fuel and a Chemical Feedstock 1995 U.S. Production 2.2 billion gallons 41% methyl t-butylether oxygenated fuels fuel cells 25% formaldehyde resins, urethane plastics, Spandex 10% acetic acid polyethylene terephthalate (PET) 27% other cleaning fluid, solvents, refrigerants, chlorine-free bleaches www.methanex.com

5. Direct Conversion of Methane to Methanol thermodynamically favored but the high temperature required to activate the strong C-H bond (439 kJ/mol) leads to overoxidation, i.e. CO 2 and H 2 O Crabtree, R. H. Chem. Rev. 1995, 95, 987-1007 Periana, R. A. et al. Science 1993, 259, 340-343 Methane Monooxygenase

6. Conversion of Methane to Methanol via Heterogeneous Catalysis Steam Reforming Crabtree, R. H. Chem. Rev. 1995, 95, 987-1007 Substantial capital investment required to implement

7. Industrial Hydrogen Production

8. Methane to Methanol Catalyzed by Soluble Pt(II) Salts CH 4 + PtCl 6 2- + H 2 O CH 3 OH + CH 3 Cl + PtCl 4 2- PtCl 4 2- 120 °C Gol'dshleger, N. F.; Es'kova, V. V.; Shilov, A. E.; Shteinman, A. A. Zh. Fiz. Khim. (Engl. Transl.) 1972, 46, 785-786

9. Alkane C-H Bond Activation Using Electron Rich Transition Metal Complexes Oxidative Addition Reductive Elimination Ir(III)Ir(I)Ir(III) Ir(I) Janowicz, A. H.; Bergman, R. G. J. Am. Chem. Soc. 1982, 104, 352-354

10. C-H Bond Activation by an Electron Rich Metal Center

11. Oxidative Addition has occurred

12. C-H Bond Activation Selectivity Radical Process Oxidative Addition by Late Transition Metal Complexes the stronger C-H bond is favored

13. A Remarkably Stable Pt(IV) Methyl Hydride O'Reilly, S. A.; White, P. S.; Templeton, J. L. J. Am. Chem. Soc. 1996, 118, 5684 Tp ’ PtMe 2 H in the solid state begins to decompose at 140 °C

14. Lewis Acid Generates a Vacant Site at Pt(II) Hill, G. S.; Rendina, L. M.; Puddephatt, R. J. J. Chem. Soc., Dalton Trans. 1996, 1809 Wouldreact similarly?

15. C-H Activation at Pt(II) Wick, D. D.; Goldberg, K. I. J. Am. Chem. Soc. 1997, 119, 10235 the first stable Pt(IV) alkyl hydride formed by alkane oxidative addition to Pt(II)

16. Proposed Mechanism of C-H Activation

17. C-H Bond Activation by an Electron Rich Metal Center Arrested State An Alkane Complex Oxidative Addition has occurred

18. Mechanism of Reductive Elimination Involves Alkane Complexes (0.7)* (0.5)* (0.75)* (0.8)*(0.77)* (0.74) (0.29)*(0.62)*

19. Pt(IV) Dimethyl Hydride Reacts with Oxygen Wick, D. D.; Goldberg, K. I. J. Am. Chem. Soc. 1999, 121, 11900

20. A Pt(IV) Dialkyl Hydroxide Hydroxide is thermally stable

21. Catalytic Functionalization of Methane by Pt(II) CH 4 + 2H 2 SO 4 CH 3 OSO 3 H + 2H 2 O + SO 2 (bpym)PtCl 2 220 °C Periana, R. A. et al. Science 1998, 280, 560-564

22. Acknowledgements

23. Synthesis of Dichloride Precursor 80 % yield 1 H-NMR

24. Structures of Isopropyl and Cyclopropyl Complexes

26. Methyl Hydride Rearrangement 1 H{ 2 H}-NMRt = 0 t = 1 h t = 3 h d, 1.236 ppm J RhH = 2 Hz d, 1.225 ppm J RhH = 2 Hz

27. Reductive Elimination of Methane t, 0.134 ppm d, -14.818 ppm J RhH = 24 Hz 1 H -NMR *

28. Loss of Methane Shows Isotope Effects Solvent k H /k D = 1.07(6) k H /k D = 0.62(7)

29. Loss of Methane is Dependent on Benzene Concentration

30. Double Reciprocal Plot Plot is consistent with saturation behavior, i.e. a reversible K eq followed by the rate determining step Plot of 1/k obs vs. 1/[C 6 D 6 ] is linear

31. Kinetic Data are Consistent with an Alkane Complex Kinetic Scheme

32. Reductive Elimination from Pt(IV) Stahl, S. S.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 1996, 118, 5961 Hill, G. S.; Rendina, L. M.; Puddephatt, R. J. Organometallics 1995, 14, 4966 a 5-coordinate intermediate is required for both reductive elimination and oxidative addition

33. Mechanism of Shilov Type C-H Bond Activation Oxidative Addition followed by Deprotonation of a Pt(IV) Alkyl Hydride Deprotonation of a Pt(II) Alkane Complex

34. C-H Activation at Pt(II) Holtcamp, M. W.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 1997, 119, 848 sigma bond metathesis oxidative addition

35. Effect of Radical Initiator/Inhibitor Tp ’ PtMe 2 H Tp ’ PtMe 2 (OOH) O 2, 1 atm C6D6C6D6

36. Reaction of Pt(IV) Dialkyl Hydride with Oxygen is Promoted by Light Tp ’ PtMe 2 H Tp ’ PtMe 2 (OOH) O 2, 1 atm C 6 D 6 /RT

37. Proposed Radical Mechanism