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Development of Constrained Geometry Complexes of Group 4 A Dissertation entitled Development of Constrained Geometry Complexes of Group 4 and 5 Metals by Ryan Thomas Rondo Submitted to the Graduate Faculty as a partial fulfillment of the requirements for the Doctor of Philosophy Degree in Chemistry Dr. Mark R. Mason, Committee Chair Dr. Patricia Komuniecki, Dean College of Graduate Studies The University of Toledo May 2010 An abstract of Development of Constrained Geometry Complexes of Group 4 and 5 Metals Ryan Thomas Rondo Submitted to the Graduate Faculty in partial fulfillment of the requirements for the Doctor of Philosophy Degree in Chemistry The University of Toledo May 2010 Constrained geometry catalysts (CGC) are known to be active in the polymerization and copolymerization of alkenes with a distinct control over polymer tacticity. The tethering of one 5-cyclopentadienyl moiety and one pendant donor gives these compounds an accessible metal center as well as ability to maintain their structure throughout the catalytic process. Complexes of this type typically feature one pendant amido donor. Replacement of the pendant amido donor with a nitrogen heterocycle such as an indolyl- or pyrrolyl-group should result in electrophilic metal centers due to reduced N M donation, a consequence of electron delocalization of the nitrogen lone pair in the aromatic system. This dissertation reports the development of a new series of constrained geometry ligands that feature indolyl- and pyrrolyl- donor moieties. iii In chapter 2, the synthesis and characterization of a series of acetal precursors and their corresponding di(3-methylindolyl)ethane and dipyrrolylethane constrained geometry ligands is reported. Within this report are two new acetal precursors, fluorenyl acetaldehyde diethylacetal, and indenyl acetaldehyde diethylacetal. Also described are the new constrained geometry ligands fluorenyl di(3-methylindolyl)ethane (H3FDI), fluorenyl dipyrrolylethane (H3FDP), indenyl di(3-methylindolyl)ethane (H3IDI), and 1 indenyl dipyrrolylethane (H3IDP). These compounds have been characterized by H and 13C NMR spectroscopy as well as mass spectrometry and elemental analysis. The molecular structure of H3FDI·THF has been confirmed by X-ray crystallography. This new set of ligands serves as a framework for constrained geometry complexes of group 4 and 5 transition metals. Chapter 3 reports the synthesis and characterization of group 4 and 5 constrained geometry complexes of fluorenyl di(3-methylindolyl)ethane (H3FDI) and indenyl di(3- methylindolyl)ethane (H3IDI). Within this report are the first examples of 3- methylindolyl-based CGC‟s of group 4 and 5 metals, specifically in the complexes (HFDI)Zr(NEt2)2(THF), (HFDI)Ti(NEt2)2, (IDI)Zr(NEt2), which were prepared using t amine elimination methods, and (IDI)Nb(N Bu)(py), (IDI)Nb(NPh), (FDI)Zr(CH3), and (FDI)Ti(CH3), which were prepared via salt metathesis. These complexes have been characterized by 1H and 13C NMR spectroscopy. X-ray crystallography confirmed the 5 bidentate nature of the HFDI ligand in (HFDI)Zr(NEt2)2(THF) as well as the - coordination of the indene moiety in (IDI)Zr(NEt2). The structures of analogous t 1 13 complexes (HFDI)Ti(NEt2)2 and (IDI)Nb(N Bu)(py) were determined by H and C 5 NMR spectroscopy. Another -coordinated complex, (FDI)Zr(CH3) was characterized iv by NMR spectroscopy. This complex exhibits a methyl resonance indicative of transition metal-methyl complexes. These constrained geometry complexes serve as a representative sample for the preparation of various CGC‟s with this ligand framework. Chapter 3 also reports the initial preparation of titanium metal-imido complexes that feature di(3-methylindolyl)methane ligands with one neutral pendant donor. Three complexes, (tBuN)Ti{(2-py)di(3-methylindolyl)methane}, (tBuN)Ti{(N- t methylimidazolyl)di(3-methylindolyl)methane}, and ( BuN)Ti{(2-MeOC6H4)di(3- methylindolyl)methane} were characterized by 1H and 13C NMR spectroscopy. X-ray crystallographic analysis of (tBuN)Ti{(2-py)di(3-methylindolyl)methane}, while incomplete, confirmed the connectivity of this complex. In chapter 4, the in situ generation of copper(I)-pyridine derivative complexes and their olefin binding properties are reported. The new complexes [(Me- nic)3Cu(NCCH3)]PF6 (Me-nic = methylnicotinate), [(3-MeOpy)3Cu(NCCH3)]PF6, and 1 13 [(3-HOpy)3Cu(NCCH3)]PF6 have been generated in situ and characterized by H and C NMR spectroscopy. These complexes were examined for their affinity to bind ethylene, propylene, 1-hexene, and cis- and trans-3-hexene. Variable-temperature NMR spectra of these alkene complexes revealed a dynamic system with fast exchange between free and coordinated alkene at temperatures as low as 80 C. Using an extrapolation method, room temperature binding constants were determined for these alkene complexes. These copper(I) compounds exhibit binding constants for ethylene and propylene that are significantly lower than those of complexes featuring multidentate amine-based donor ligands. Furthermore, these complexes do not appear to bind 1-hexene, cis-3-hexene, or trans-3-hexene. v Appendix 1 reports the synthesis and characterization of metallophosphinate complexes of aluminum and gallium. These complexes are believed to consist of a M2P2O4 (M = Al, Ga) ring structure, which was confirmed by X-ray crystallographic analysis of [Ph2AlO2PPh2]2. Specifically, the complexes [Ph2AlO2PPh2]2, [Ph2GaO2PPh2]2, [Ph2AlO2P(OPh)2]2, and [Ph2GaO2P(OPh)2]2 have been synthesized. Also reported in this appendix are reactions of triphenylaluminum and triphenylgallium with phosphonic acids. Products isolated in reactions with phosphonic acids were difficult to characterize due to their insoluble nature and amorphous morphology. vi For my wife and my family whose patience and support guided me through these years. And especially for my father, who always encouraged me to succeed. Acknowledgement I would like to give thanks and express appreciation for my advisor, Dr. Mark R. Mason. His continued guidance has proven invaluable to my development as a chemist. Acknowledgement is needed for Dr. Bruce A. Averill for his guidance throughout the initial stages of my graduate career. I would also like to thank Drs. Joseph Schmidt, Cora Lind, and Maria Coleman for serving on my committee. I would like to thank to Dr. Kristin Kirschbaum for her help in solving crystal structures. Thanks go to Mark R. Giolando and William Scharer who assisted Dr. Kirschbaum with work on the structure of 51·THF. Thanks go to Dr. Yong-Wah Kim, for help with NMR spectroscopy. I am grateful to Steve Moder for his fabrication of glassware for my experiments. Thanks go to Pannee Burckel and Kristi Mock for elemental analysis work. I would like to thank my group members Dr. Nicholas Kingsley, Chris Yeisley, Adam Keith, Emmanuel Tive, Chris Gianopoulos, Anirban Das, Michael Helmstadter, and Leonard Nyadong for their support. I am grateful for partial financial support provided by The University of Toledo Interdisciplinary Research Initiation Award (Prof. Mark Mason, PI), which was used in the research reported in chapters 2 and 3. Finally I would like to thank my family and friends for their support. To my wife, Shannon, I appreciate your unwavering love and support through this time. I would not be the person I am today without you. viii Table of Contents Abstract iii Acknowledgements viii Table of Contents ix List of Appendix Contents xi List of Figures xii List of Tables xv List of Abbreviations xvi Chapter 1 Group IV and V Transition Metal Complexes: A Concise Review of Constrained Geometry Catalysts and Transition Metal Imido Complexes 1.1 Introduction 1 1.2 Ziegler-Natta and Phillips-Type Catalysts 2 1.3 Single-Site Catalysts 5 1.4 Catalyst Activation 7 1.5 Constrained Geometry Catalysts 9 1.6 Recent Constrained Geometry Catalysts 12 1.7 Transition Metal-Imido Complexes 15 1.8 Research Statement 19 ix Chapter 2 Trianionic Indole- and Pyrrole-Based Constrained Geometry Ligands 2.1 Introduction 23 2.2 Experimental 28 2.3 X-ray Crystallography 37 2.4 Results and Discussion 38 2.4.1 Synthesis of Diethylacetals 39 2.4.2 Synthesis of Constrained Geometry Ligands 43 2.5 Conclusions 54 Chapter 3 Constrained Geometry and Related Complexes of Group 4 and 5 Metals 3.1 Introduction 55 3.2 Experimental 61 3.3 X-ray Crystallography 71 3.4 Results and Discussion 74 3.4.1 Preparation and Characterization of (HFDI)M(NEt2)2 75 3.4.2 Preparation and Characterization of (IDI)Zr(NEt2) 82 3.4.3 Preparation and Characterization of (FDI)M(CH3) 87 3.4.4 Preparation and Characterization of 91 (IDI)Nb(=NR)(py)x; (x = 0, 1) 3.4.5 Titanium-Imido Complexes of 94 Di(3-methylindolyl)methanes 3.5 Conclusions 99 x Chapter 4 Olefin Binding Studies of Copper(I) Pyridine Derivative Complexes 4.1 Introduction 101 4.2 Experimental 109 4.3 Results and Discussion 117 4.3.1 In-situ Generation of Copper-Olefin Complexes 117 4.3.2 Olefin Binding Studies 118 4.4 Conclusions 126 Chapter 5 Concluding Remarks 127 References 132 Appendix 1 Molecular Phosphinates and Phosphonates of Aluminum and Gallium A.1 Introduction 145 A.2 Experimental 148 A.3 X-ray Crystallography 153 A.4 Results and Discussion 154 A.5 Conclusions 161 A.6 References 162 Appendix 2 CIF Files for Compounds CIF File for H3FDI·THF 166 CIF File for (HFDI)Zr(NEt2)2(THF) 181 CIF File for (IDI)Zr(NEt2) 202 xi List of Figures Figure 1.1 Zielger-Natta polymerization mechanism for the formation of 4 isotactic polypropylene. Figure 1.2 Different tacticity forms of polypropylene. 5 Figure 1.3 Typical constrained geometry catalysts. 10 Figure 2.1 Typical constrained geometry ligand structure. 24 Figure 2.2 Numbering schemes for indole, fluorene, and 28 indene, respectively. Figure 2.3 1H NMR spectrum of fluorenyl acetaldehyde diethylacetal (48). 41 Figure 2.4 1H NMR spectrum of the aliphatic region of 49.
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