AN ABSTRACT OF THE DISSERTATION OF Danielle C. Hutchison for the degree of Doctor of Philosophy in Chemistry presented on December 5, 2019. Title: Synthesis and Solution Characterization of Metal-Oxo Photoresist Precursors Abstract approved: ______________________________________________________ May Nyman Metal-oxo clusters can be described as soluble pieces of metal-oxide frameworks. Currently, metal-oxo clusters are being considered as solution-based precursors for extreme ultraviolet (EUV, 13.5 nm) photoresist materials, which are a crucial component in the fabrication of microelectronic devices. Two different photoresist precursor systems have been investigated – alkyltin clusters and zirconium peroxide clusters. Four new butyltin structures have been crystallized, all having the β or γ Keggin topology: β-[(BuSn)12(NaO4)(OCH3)12(O)5(OH)7] (β-NaSn12), γ-[(BuSn)12(NaO4)(OCH3)12(O)5(OH)7] (γ-NaSn12), γ-[(BuSn)12(NaO4)(OCH3)11(O)7(OH)6(BuSnOCH3)] (γ-NaSn13), 2+ β-[(BuSn)12(CaO4)(OCH3)12(O)4(OH)8] (β-CaSn12). All four of these were synthesized by hydrolysis of BuSnCl3 with either NaOH or Ca(OH)2 in methanol. Two new zirconium peroxide structures have been characterized as well – an oxo-centered tetrahedron [Zr4(OH)4(μ-O2)2(μ4-O)(H2O)12](ClO4)6xH2O (ZrTd) and a 25- membered wheel structure [Zr25O10(OH)50(O2)5(H2O)40](ClO4)10xH2O (Zr25). All of these new structures have been characterized extensively in solution by techniques including multinuclear NMR, small angle x-ray scattering (SAXS), and electrospray-ionization mass spectrometry (ESI-MS). The alkyltin Keggin system is unique in that only the rarer β and γ isomeric forms have been crystallized. Furthermore, the Na-centered clusters have only been isolated as a mixture of β and γ isomers. We have therefore explored several factors which may influence the Keggin isomer such as the charge of the octahedral metal, the size and charge of the central metal, and the effects of aging, solvent, and heating. Changing the central metal from Na to Ca resulted in the stabilization of the β-isomer. Density functional theory computations ranked the relative stabilities of these clusters γ-CaSn12 < γ-NaSn12 < β- CaSn12 < β-NaSn12. Aging of Na- and Ca-centered clusters was studied in air by FT-IR and 1 in organic solvents (C6D6, CDCl3, 9:1 C6D6:MeOD, 9:1 CDCl3:MeOD) by H NMR. Results showed hydrolysis of the bridging methoxy ligands due to ambient humidity or residual water in the organic solvents. Addition of excess deuterated methanol was also found to increase the rate of hydrolysis resulting in the following order: C6D6 < 119 C6D6/MeOD < CDCl3/MeOD ≈ CDCl3. Characterization by variable-temperature Sn NMR showed that the formation of additional isomers can be promoted by heating 23 solutions of NaSn12 and CaSn12 in C6D6. Na NMR characterization of heated solutions of NaSn12 showed five chemical shifts, corresponding to all five Keggin isomers simultaneously in solution. The aqueous chemistry of zirconium is typically dominated by the ubiquitous square tetramer (Zr4) which spontaneously assembles upon dissolution of zirconium oxyhalide salts at low pH. By exchanging the halide with perchlorate and adding peroxide to the solution, we were able to crystallize two new topologies. Adding 1:1 peroxide/Zr resulted in Zr25, and adding 10:1 peroxide/Zr resulted in ZrTd. To shed light on the role of peroxide in these systems, the reaction pathway was monitored by SAXS and pair distribution function (PDF). These studies revealed that when excess peroxide is present, in the case of ZrTd, a large cluster species initially forms in solution before breaking down into the smaller tetrahedral cluster. Conversely, without excess peroxide, small trimer and pentamer fragments are formed in solution which then assemble into Zr25 in the solid state at the interface between crystal and solution. The highly acidic nature of this solution prevents formation of the large cluster in the solution state. The trimer and pentamer fragments have also been observed by ESI-MS and the intact Zr25 is never observed in water by any solution characterization methods. ©Copyright by Danielle C. Hutchison December 5, 2019 All Rights Reserved Synthesis and Solution Characterization of Metal-Oxo Photoresist Precursors by Danielle C. Hutchison A DISSERTATION submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Presented December 5, 2019 Commencement June 2020 Doctor of Philosophy dissertation of Danielle C. Hutchison presented on December 5, 2019 APPROVED: Major Professor, representing Chemistry Head of the Department of Chemistry Dean of the Graduate School I understand that my dissertation will become part of the permanent collection of Oregon State University libraries. My signature below authorizes release of my dissertation to any reader upon request. Danielle C. Hutchison, Author ACKNOWLEDGEMENTS To Dr. May Nyman, for your endless dedication to helping me become the best scientist that I can be and for providing me with so many opportunities to grow and learn. To all former and present Nyman research group members, especially: Morgan Olsen, for keeping me company during countless meetings and joining me into the exploration of tin chemistry. Dr. Dylan Sures, for always being available to discuss science, current events, or life in general. Ana Arteaga and Rachelle Smith, for always being down to get froyo with me and for any and all office conversations – scientific or otherwise. To my wonderful husband, Adam – thank you for always loving me and encouraging me to reach my goals. You are a wonderful father to our son, and I wouldn’t have been able to do any of this without your support. To Parker – I love being your mom more than anything, and watching you grow and learn brings me so much joy. I hope you never lose your sense of curiosity and excitement. To all my friends and family, for supporting me through this crazy journey of graduate school, parenting, and living on the opposite side of the country. CONTRIBUTION OF AUTHORS M.N. provided significant guidance for all experiments, interpretation of results, and manuscript writing. In Chapter 3, M.R.O aided in the synthesis and crystallization of two reported structures (β-NaSn12 and γ-NaSn13) In Chapters 3 and 4, R.D.S. performed all computational experiments and assisted in writing the computational portion of the manuscripts, and L.N.Z. performed single-crystal x-ray diffraction and solved all reported structures. K.A.P. provided computational insight. In Chapter 6, J.A.S. synthesized and crystallized all reported structures, and N.P.M performed single-crystal x-ray diffraction and solved crystal structures. K.K. collected x-ray total scattering data and performed PDF analysis; D.A.K. provided insight on manuscript writing. TABLE OF CONTENTS Page 1 Introduction to Metal-Oxo Clusters and the Keggin Structure.................................... 1 1.1 Metal-Oxo Clusters ................................................................................................. 1 1.1.1 Characterization of Metal-Oxo Clusters ............................................................ 1 1.2 The Keggin Structure .............................................................................................. 3 1.3 Monoorganotin-Oxo Clusters ................................................................................... 7 1.4 Zirconium and Hafnium Metal-Oxo Clusters .......................................................... 12 2 Nanolithography and Metal-Oxo Photoresists .......................................................... 15 2.1 Nanolithography ................................................................................................... 15 2.2 Metal-Oxo Photoresists ......................................................................................... 18 2.2.1 Hf/Zr-Oxo Cluster Photoresists ...................................................................... 18 2.2.2 Organotin Photoresists ................................................................................... 19 3 Alkyltin Clusters: The Less Symmetric Keggin Isomers .......................................... 21 3.1 Abstract ............................................................................................................... 22 3.2 Introduction .......................................................................................................... 22 3.3 Experimental ........................................................................................................ 25 3.3.1 Synthetic Methods ......................................................................................... 25 3.3.2 Characterization Techniques .......................................................................... 25 3.3.3 Computational Methods ................................................................................. 27 3.4 Results and Discussion .......................................................................................... 28 3.4.1 Solution characterization ................................................................................ 32 3.4.2 Computational Studies ................................................................................... 37 3.5 Conclusions .......................................................................................................... 41 3.6 Acknowledgements ............................................................................................... 42 4 Synthesis and Characterization