1. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ C-H Functionalization: Shilov Chemistry Allegra Liberman-Martin, Levi Moore, Drexel Proctor, and Giselle Sullivan Chem 165: Organometallic Chemistry Fall 2009 This presentation was created as part of the requirements for Chemistry 165 "Organometallics" at Harvey Mudd College during the fall semester 2009. The authors of this presentation are Allegra Liberman-Martin (Scripps College), Levi Moore (Pomona College), Drexel Proctor (Pomona College) and Giselle Sullivan (Scripps College).

2. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Current methane conversion methods are indirect Synthesis gas method Goal: Direct conversion of methane to methanol Challenging aspect: increasing reactivity of oxidation products Comparing Bond Dissociation Energies (BDEs): BDE(C-H, methane) = 104 kcal/mol BDE(C-H, methanol) = 93 kcal/mol Methane Utilization

3. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Radical Chain Oxidation of Alkanes vs. Oxenoid Mechanism Muradov, N. Z.; Shilov, A. E.; Shteinman, A. A., Reac. Kin. and Cat.Lett. 1975, 2, 417-423. Shilov, A.E.; Shteinman A.A. Acc. Chem. Res. 1999, 32, 763, 771. Radical Chain Oxidation RH + O 2  R + HOO R + O 2  ROO ROO + RH  ROOH + R Dioxygen causes initiation and propagation of chains. ROOH + M n  M n+1 + RO - + OH Compounds of transition metals can also participate in the propagation of radicals. The radical mechanism is a 1e - process. Oxenoid Mechanism RH + 2e - + 2H + + O 2  ROH + H 2 O Hydroxylation of C-H bond of a hydrocarbon coupled with oxidation of electron donors. Requires interaction with a metal core, either in a synthesized catalyst or an enzyme. The oxenoid mechanism is a 2e - process, and does not involve the formation of radicals. Both major systems currently in use proceed through an oxenoid type mechanism.

4. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Shilov System First transition metal system for alkane functionalization Catalytic in Pt(II), but requires stoichiometric Pt(IV) Because methyl undergoes nucleophilic attack by both water and chloride ions in solution, both CH 3 OH and CH 3 Cl are generated Luinstra, G. A.; Labinger, J. A.; Bercaw, J. E. J. Am. Chem. Soc. 1993, 115, 3004-3005. Lunistra, G. A.; Wang, L.; Stahl, S. S.; Labinger, J. A.; Bercaw, J. E. J. Organomet. Chem. 1995, 504, 75-91.

5. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Shilov System - Rate Determining Step Two steps in question: 1.Methane uptake methane platinum complex precursor for C–H 2.C-H activation Rate Determining Step: methane uptake –Associative vs. dissociative pathway –Ligand dependency (see respective rate laws) Zhu, H.; Ziegler, T. J. Organomet. Chem. 2006. 691, 4486.

6. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Shilov System: Methane Uptake Associative mechanism for methane uptake Dissociative mechanism for methane uptake Zhu, H.; Ziegler, T. J. Organomet. Chem. 2006. 691, 4486.

7. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Catalytica Systems 85% selectivity for methyl bisulfate 50% conversion of methane 81% selectivity for methyl bisulfate 89% conversion of methane Hydrolysis of methyl bisulfate to methanol is necessary. Periana, R. A.; Taube, D. J.; Evitt, E. R.; Loffler, D. G; Wentreck, P. R.; Voss, G.; Masuda, T. Science 1993, 259, 340-343. Periana, R. A.; Taube, D. J.; Gamble, S.; Taube, H.; Satoh, T.; Fuhii, H. Science 1998, 280, 560-564.

8. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Vanadate Catalysis Vanadate/pyrazine-2-carboxylic acid catalysis –Less extreme reaction conditions Industrial impact for C-H functionalization Forms methanol, formic and acetic acid Süss-Fink, G.; Stanislas, S.: Shul'pin, G.B.; Nizova, G.V. Appl. Organomet. Chem. 2000, 14, 623-628.

9. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Gold in the Shilov Reaction System Au(I) is isoelectronic with Hg(II); Au(III) with Pt(II) Selenic acid (H 2 SeO 4 ) used as oxidant, rather than Pt(IV) Methane converts to methyl bisulfate, which is hydrolyzable to methanol De Vos, D. E.; Sels, B. F.. Angew. Chem. Int. Ed. 2004, 44, 30-32.

10. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Construction of MOF Wanted to construct a heterogeneous catalyst for Shilov reaction Used Gd and Pt(BPDC)Cl 2 in MOF Catalytic site structure retained Szeto, K. C.; Kongshaug, K. O.; Jakobsen, S.; Tiset, M.; and Lillerud, K. P. Royal Soc. Chem. 2008, 2054-60. Image (Figure 1, p. 2057) from “Design, synthesis, and characterization of a Pt-Gd metal-organic framework containing potentially catalytically active sites.” Szeto, K. C.; Kongshaug, K. O.; Jakobsen, S.; Tiset, M.; and Lillerud, K. P. Royal Soc. Chem. 2008,2054-2060.

11. Created by Allegra Liberman-Martin (aliberma@scrippscollege.edu), Drexel Proctor, Levi Moore, and Giselle Sulivan and posted on VIPEr on December 2009. Copyright Allegra Liberman-Martin 2009. This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License. To view a copy of this license visit http://creativecommons.org/about/license/http://creativecommons.org/about/license/ Formation of Lactones Best with typical Shilov Pt(II) catalyst and Pt(IV) oxidant (60%yield) Second best with Cu(II) oxidant (56%yield with 3 eq.) Can be monomers for organic synthesis, materials science, polymers, or biological molecules Lee, J. M., and Chang, S. Tetra. Lett. 2006, 47, 1375-1379.