DEVELOPMENTS IN THE SYNTHESIS OF ZWITTERIONIC OLEFIN POLYMERIZATION CATALYSTS By H. JERROLD MILLER A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULHLLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1997 ACKNOWLEDGEMENTS First and foremost, I need to thank my parents. Because of them, I am who I am today, and without their guidance, support, and love, none of this would have been possible. I haven't been the closest son since I moved away, first to college and then to grad school, but just knowing that they loved me and were there if I needed them was comforting. I also want to thank my sister, Kathie, who has been very supportive and a great sister. My two advisors, Dave Richardson and Jim Boncella, were obviously instrumental in my conversion from a short order cook, following recip>es of others, into a first class chef, making my own recipes for others to follow. Dave has shown me the importance of understanding fundamental concepts, and has been extremely successful in finding ways to motivate me in my less productive times. His enthusiasm for my chemistry has been very refreshing and often has helped me push that extra yard to get the results. In the last five years, he has become a good friend, as well as a mentor. Jim has shown me the importance of keeping track of the literature. He has worked hard to break me of my habit of reinventing the wheel. Most importantly, Jim taught me everything I know about working with air- and moisture-sensitive chemicals, without which none of this dissertation would have been successful. He has given me the skills that will allow me to be successful for the rest of my career, for which I am eternally grateful. 11 The author wishes to acknowledge Dr. Khalil Abboud, not only for solving and helping interpret all of the crystal structures, but also for being very patient with the author over the last four years. All members, both past and present, of the Richardson and Boncella groups also need to be recognized. They include Perla Izsak, Steve Wang, Ryan Mills, Jon Penney, Carlos Ortiz, Dan Vandelende, Will Vaughn, Larry Villaneueva, Laura Blosch, Celeste Regino, Ken Weakly, Derika Rivers, Maureen Burkhart, Tu-cai Zheng, Faisal Shafiq, and George Alameddin. I especially need to thank Percy Doufou, Joy Mendez, Matt Ryan, and Dave Knoeppel for being great friends as well as coworkers. Unfortunately, there is not room or time for me to explain how instrumental all of these people have been in my development with their support, advice, criticism, humor, and friendship, so just let me say THANKS. Two special friends require special recognition. Tom Hayes has been a best friend for the last eight years, and making the trip from Ohio to Horida was especially easy knowing such a good friend was going with me. Dominick Valenti became a great friend in the last four years, and many questions about both chemistry and women were solved by the two of us over drinks at the Porpoise and elsewhere. Of course, I need to acknowledge Sheeba, Harry, and Jenny for their never-ending love and loyalty. I could almost feel my blood-pressure dropping as I got a therapeutic cuddle from any of the three of them. Finally, and most importantly, I need to thank my new wife. Heather. She has made the last four years of my life wonderful, and I look forward to spending the rest of our lives together. There have been many times when things seemed terrible, and I felt like it would never get better, but her love and support has help>ed me p>ersevere, and I will love her forever. Ill TABLE OF CONTENTS ACKNOWLEDGEMENTS ii ABSTRACT vii CHAPTERS 1 INTRODUCTION 1 History of Heterogeneous Systems 1 History of Homogeneous Systems 4 2 APPLICATION OF HYDROBORATION TO THE SYNTHESIS OF ZWITTERIONIC, GROUP 4 SINGLE-SITE POLYMERIZATION CATALYSTS 23 Introduction 23 Experimental Section 24 General Considerations 24 Procedures 25 Results and Discussion 28 Syntheses 28 Hydroboration Reactions 30 Conclusions 38 3 SYNTHESIS, CHARACTERIZATION, AND STRUCTURE OF NOVEL BORANE- AND BORATE-CONTAINING RUTHENOCENES 40 Introduction 40 Experimental Section 42 General Considerations 42 Procedures 43 X-Ray Structural Analysis of 3-3 45 X-Ray Structural Analysis of 3-6b 46 Results and Discussion 47 Syntheses 47 NMR Studies 51 X-Ray Structural Analyses 64 iv Oxidation Reactions With 3-6 Conclusions ^ 4 SYNTHESIS, CHARACTERIZATION, AND STRUCTURE OF GROUP 4 METALLOCENES CONTAINING THE FUNCnONALIZABLE P-HALOPHENYL(DIMETHYL)METHYL- CYCLOPENTADIENYL LIGAND 67 Introduction Experimental Section 69 General Considerations 69 Procedures X-Ray Structural Analysis of 4-1 and 4-3 72 Results and Discussion S)mtheses X-Ray Structural Analyses 75 Reactions of Zirconocenes Conclusions 5 THE APPLICATION OF TIN-COUPLING METHODS TO THE SYNTHESIS OF ZWITTERIONIC GROUP 4 METALLOCENES 85 Introduction 85 Experimental Section 87 General Considerations 87 Procedures 88 Results and Discussion Future Work 6 SYNTHESIS, CHARACTERIZAHON, AND REACTIVITY OF NOVEL BORATE-CONTAINING BRIDGING CYCLOPENTADIENYL-SILYL-AMIDO COMPLEXES 99 Introduction Experimental Section General Considerations 101 Procedures Results and Discussion 116 7 SYNTHESIS OF DIIMINE LIGANDS AND LIGAND PRECURSORS FOR THE DEVELOPMENT OF ZWITTERIONIC, LATE TRANSITION METAL DHMINE CATALYSTS 144 Introduction Experimental Section I45 General Considerations I45 Procedures 245 Results and Discussion 8 SUMMARY 250 APPENDDC LIST OF REFERENCES 203 BIOGRAPHICAL SKETCH 919 vi Abstract of Dissertation Presented to the Graduate School of the University of Horida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy DEVELOPMENTS IN THE SYNTHESIS OF ZWITTERIONIC OLEFIN POLYMERIZATION CATALYSTS By H. Jerrold Miller August, 1997 Chairmen: David Richardson/James Boncella Major Department: Chemistry Potential methods for the synthesis of zwitterionic, single-site polymerization catalysts were examined, and a number of complexes were prepared. The prepared complexes are early transition metal metallocenes, which are not zwitterionic species, and ansfl-silyl-bridged cyclopentadienyl- amido (Cp-amido) complexes, some of which are zwitterionic species. In the process of preparing these complexes, model ruthenocene complexes were prepared employing the same ligands, and their reactivity was also examined. A series of metallocene complexes were prepared by using Cp ligands derived from 6,6-dimethylfulvene. The addition of lithium diisopropylamide (LDA) to 6,6-dimethylfulvene leads to deprotonation of the p-exo carbon and the synthesis of the anionic methylvinyl-Cp, CpCsHs, ligand. This ligand was used to prepare a series of metallocenes, and the vii reactivity of these complexes toward hydroboration with Ph2BH»Py was examined. The ruthenocene reacted with the borane yielding reduction of the double bond. However, with zirconocenes, reactivity was observed between the borane and the metal center. With the dimethyl zirconocene, this led to a new complex whose structure is proposed based on spectroscopic data. A new Cp ligand, also based on 6 ,6-dimethylfulvene, was prepared by the addition of (p-bromo- or (p-iodophenyl)lithium to 6 ,6-dimethylfulvene. This yielded the anionic Cp ligand CpC(CH3)2C6H4X (X=Br, I) from which was prepared a number of metallocenes. When an 18 electron ruthenocene complex was prepared with the ligand, halo-lithium exchange occurred at the ligand, and trapping the resulting lithiate with boranes yielded a borate- containing ruthenocene, and a borane-containing ruthenocene. Similar chemistry was attempted with 16 electron zirconium complexes, however reactivity occurred at the metal center. Since it was not possible to prepare borate-containing metal complexes after the ligand was coordinated to early transition metals, methods for preparing the borate-containing ligand prior to coordination were examined. Preliminary studies using tin-coupling methods appear promising for the synthesis of borate-containing metallocenes, and more work is required to fully understand these systems. The use of silyl-bridged cyclopentadienyl- amido ligands has proven to be a very successful method for the s)mthesis of borate-containing ligands, and metal complexes containing these ligands have been prepared. In the process, a series of borate-containing aniline derivatives have been prepared, which appear to have a great deal of potential as ligands in transition metal chemistry. viii CHAPTER 1 INTRODUCTION History of Heterogeneous Systems. While studying the formation of long-chain trialkylaluminum compounds via the insertion of ethylene into Al-C bonds, Karl Ziegler and coworkers made a serendipitous discovery. When trace amounts of a nickel compoimd were left from a previous hydrogenation reaction in the autoclave, the only product observed was 1-butene. This became known as the "nickel effect," and led Ziegler to examine the effect of other heavy metals on the insertion reaction. Then, in late 1953, Ziegler and coworkers^ found that the presence of zirconium acetylacetonate during the reaction led exclusively to high molecular weight polyethylene (HMWPE) at ambient temperatures and pressures. This discovery was astonishing considering polyethylene (PE) was previously only prepared by a radical mechanism under extremely harsh conditions of high temp>erature and pressure. Ziegler and coworkers2 soon established that the best catalyst systems for the polymerization of ethylene to high density polyethylene (HOPE) consisted of a