STUDIES OF CARBENE-SOLVENT INTERACTIONS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Eric M. Tippmann, B.S. ***** The Ohio State University 2003 Dissertation Committee: Approved by Professor Matthew S. Platz, Adviser Professor Terry L. Gustafson Professor Christopher M. Hadad Adviser Department of Chemistry ABSTRACT Several new tricyclic-carbene precursors have been synthesized. Photolysis (266, 300, or 308 nm) of these precursors generates free carbenes in solution. This was demonstrated through trapping studies performed with pyridine and tetramethylethylene. The new carbenes (chlorofluoro-, fluorocarbomethoxy-, chloro- and fluoroamidecarbenes) were fully characterized by laser flash photolysis techniques using time-resolved infrared and UV-Vis spectroscopy. The new carbenes, along with several other known carbenes, were utilized in the study of carbene-solvent interactions. One class of carbenes, the haloamide carbenes, demonstrated significant solvent-dependent chemistry. Both time resolved infrared and UV-Vis spectroscopy generated results indicative of significant carbene-solvent interactions. Generally, ethereal solvents were able to retard the bimolecular reactivity of chloro- and fluoroamidecarbenes with carbene traps. The lifetime of the carbene was also dramatically extended in some cases. Time- resolved infrared spectroscopy was able to directly observe the chloroamide carbene solvated by small amounts of dioxane in Freon-113. Other potentially ligating solvents, such as benzene and acetonitrile for example, did not demonstrate similar reactivity. Density Functional and MP2 theoretical calculations were performed to assist in assigning reactive intermediates as well as determining reaction barriers. ii To Sohie iii ACKNOWLEDGMENTS I thank my adviser for supplying a lifetime's worth of example to follow, both personally and professionally. iv VITA September 13, 1972 .....................Born – Fort Wayne, Indiana 1998..............................................B.S. Chemistry, Purdue University, Fort Wayne 1999 – Present..............................Graduate Teaching and Research Associate, The Ohio State University PUBLICATIONS Likhotvorik, I. R.; Tippmann, E.; Platz, M. S. Bimolecular chemistry of dimethylcarbene. Tetrahedron Letters (2001), 42(17), 3049. Likhotvorik, Igor; Zhu, Zhendong; Tae, Eunju Lee; Tippmann, Eric; Hill, Brian T.; Platz, Matthew S. Carbomethoxychlorocarbene: Spectroscopy, Theory, Chemistry and Kinetics. Journal of the American Chemical Society (2001), 123(25), 6061. Tae, Eunju Lee; Ventre, Celine; Zhu, Zhendong; Likhotvorik, Igor; Ford, Francis; Tippmann, Eric; Platz, Matthew S. Rearrangement of 1-Noradamantyl and 1- Adamantylcarbene to Bridgehead Alkenes: Lifetimes of Two Bridgehead Carbenes in Solution. Journal of Physical Chemistry A (2001), 105(44), 10146. Sun, Ying; Tippmann, Eric M.; Platz, Matthew S. A Search for Carbene-Solvent Interactions Using Time-Resolved Infrared Spectroscopy. Organic Letters (2003), 5(8), 1305 Tippmann, Eric M.; Platz, Matthew S. Laser Flash Photolysis Study of Chlorofluorocarbene. Journal of Physical Chemistry A (2003), 107(41), 8547 FIELDS OF STUDY Major Field: Chemistry v TABLE OF CONTENTS Abstract...............................................................................................................................ii Acknowledgements............................................................................................................ iv Vita...................................................................................................................................... v List of Tables ...................................................................................................................viii List of Figures..................................................................................................................... x List of Schemes.............................................................................................................xxvii Chapters: 1. Introduction..................................................................................................................... 1 2. Fluorochlorocarbene ....................................................................................................... 9 2.1. Introduction........................................................................................................9 2.2. Results................................................................................................................9 2.3. Discussion........................................................................................................25 2.4. Conclusions......................................................................................................28 3. Carbomethoxyfluorocarbene......................................................................................... 29 3.1. Introduction......................................................................................................29 3.2. Results..............................................................................................................30 3.2.1. Laser Flash Photolysis ........................................................................ 33 3.2.2. Density Functional Calculations......................................................... 38 3.2.3. Time Resolved Infrared Spectroscopy................................................ 41 3.2.4. Matrix Isolation................................................................................... 47 4. Time Resolved Infrared Studies of Fluorophenyl Carbene .......................................... 49 4.1. Introduction......................................................................................................49 4.2. Results and Discussion ....................................................................................50 vi 5. Haloamidecarbenes....................................................................................................... 57 5.1. Introduction......................................................................................................57 5.2. Results..............................................................................................................58 5.2.1. Density Functional Theoretical (DFT) Calculations........................... 60 5.2.2. Laser Flash Photolysis with UV-Vis Detection.................................. 68 5.2.3. Time Resolved Infrared (TRIR) Spectroscopy................................... 94 5.2.4. 18-Crown-6—carbene complexes. ................................................... 122 6. Ketene and Oxiranylcarbene Precursors..................................................................... 124 6.1. Introduction....................................................................................................124 6.2. Photochemistry ..............................................................................................126 6.3. Oxiranyl carbene............................................................................................138 7. Miscellaneous ............................................................................................................. 152 7.1. Carbenoids .....................................................................................................152 7.2. Thiophenylcarbene.........................................................................................163 7.3. Potpourri ........................................................................................................171 Bibliography ................................................................................................................... 181 Appendix A..................................................................................................................... 185 Appendix B. .................................................................................................................... 272 vii LIST OF TABLES Table 2.1. Measurement of kobs and τ as functions of the concentration of precursor 1 in heptane................................................................................................ 22 Table 2.2. Calculated and experimental νC-F frequencies................................................. 25 Table 2.3. Calculated (TD-DFT) absorption spectra of diene 1, ylide 4, and triene 5. ............................................................................................................... 25 Table 3.1. Comparison of the absolute rate constants of fluoro- and carbomethoxychlorocarbenes with various quenchers. ............................................. 36 Table 5.1. TD-DFT UV/Vis transitions for 22Cl............................................................. 62 Table 5.2. TD-DFT UV/Vis transitions for 22F. ............................................................. 62 Table 5.3. TD-DFT UV/Vis transitions for 24Cl............................................................. 62 Table 5.4. TD-DFT UV/Vis transitions for 24F. ............................................................. 63 Table 5.5. TD-DFT UV/Vis transitions for 25Cl............................................................. 64 Table 5.6. TD-DFT UV/Vis transitions for 25F. ............................................................. 65 Table 5.7. Basis Set Superposition error along with barriers from the PES of 21Cl with dimethylether (Energies reflect Zero Point Energy