UNIVERSITY OF OKLAHOMA GRADUATE COLLEGE CHEMICAL MODELING OF UNSTABLE INTERMEDIATES IN HEME−MEDIATED NOX BIOLOGY A DISSERTATION SUBMITTED TO THE GRADUATE FACULTY in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY By ERWIN G. ABUCAYON Norman, Oklahoma 2017 CHEMICAL MODELING OF UNSTABLE INTERMEDIATES IN HEME−MEDIATED NOX BIOLOGY A DISSERTATION APPROVED FOR THE DEPARTMENT OF CHEMISTRY AND BIOCHEMISTRY BY ______________________________ Dr. George B. Richter-Addo, Chair ______________________________ Dr. Mark A. Nanny ______________________________ Dr. Ann H. West ______________________________ Dr. Robert K. Thomson ______________________________ Dr. Zhibo Yang © Copyright by ERWIN G. ABUCAYON 2017 All Rights Reserved. This work is dedicated to my beloved parents and siblings. Acknowledgments I would like to express my sincere gratitude to my research mentor, Dr. George B. Richter-Addo for his unconditional support and for always believing in me. I am extremely fortunate and grateful for his motivation, unwavering enthusiasm, and immense knowledge in bioinorganic research. My sincere thanks goes to my research advisory committee; Drs. Daniel Glatzhofer, Ann West, Robert Thomson, Zhibo Yang, and Mark Nanny for their suggestions and advice throughout my graduate studies. I would like to give special thanks to both past and present members of the Richter-Addo laboratory; to (i) Dr. Dennis Awasabisah who introduced me to the lab and taught me new synthetic skills, spectroscopy, and electrochemical techniques during my first year, (ii) Dr. Nan Xu who provided the foundation that forms the basis of the first chapter of my dissertation, (iii) Dr. Jun Yi for the many interesting scientific discussions that we had, and (iv) Dr. Guan Ye, Dr. Bing Wang, Neda Hessami, Jimmy Herndon, Samantha Powell, Jeremy Zink, Mike Gorbett, Viridiana Hererra, and Megan Ayala for the stimulating conversations that we had about science and non-science matters. I would like to thank our research collaborators; Dr. Mike Shaw (SIUE) for research discussions and critical suggestions regarding some of our experiments, Dr. Yong Zhang (SIT) for the very fruitful collaboration and the time that he spent performing advanced DFT calculations to verify some of our novel experiments, Dr. Naresh Dalal (FSU) for the advanced EPR and magnetization studies for our iron−NONOate complexes, and Dr. Ralph Tanner (OU Department of Microbiology and Plant Botany) for conducting gas chromatographic detection (GC-TCD) of H2 gas for one of our iv important HNO experiments. I was also deeply indebted to the research support staff in our department; to Dr. Douglas Powell for his patience in helping me with my crystallographic work; Dr. Susan Nimmo for her assistance with low temperature NMR spectroscopy; Dr. Steve Foster for helping me with mass spectrometry; Jim Cornell for the glass-blowing work, as well as Chad, Karl, and Jeff in the electronic shop for all their help. I am very grateful to my family who were a constant source of my strength during my Ph.D. studies. Special thanks to my special someone, Melissa Borlagdan, for the unconditional love, support, understanding, and encouragement throughout my Ph.D. years. We are extremely grateful to the U.S. National Science Foundation (CHE- 1213674 and CHE-1566509) for funding this work. Finally, I would like to express my gratitude to the university for the Nancy Mergler Dissertation Completion Fellowship (OU) during the final year of my graduate work. v Table of Contents Page Acknowledgments ………………………………………………………….. iv List of Tables ……………………………………………………………….. xi List of Figures ………………………………………………………………. xii Abstract …………………………………………………………………….. xviii Chapter 1 Introduction …………………………………………………. 1 Introduction …………………………………………………................ 1 References …………………………………………………………….. 7 Chapter 2 Six-coordinate Ferric Porphyrins Containing Bidentate N-t-Butyl-N-nitrosohydroxylaminato Ligands: Structure, Magnetism, IR spectroelectrochemisty, and Biologically Relevant Reactivity …………………………………………. 10 2.1 Introduction ………………………………………………………... 10 2.2 Results and Discussion …………………………………………….. 13 2.2.1 Synthesis ………………………………………….................. 13 2.2.2 Molecular Structure ………………………………………….. 14 2.2.3 Magnetic Behavior …………………………………………... 19 2.2.4 Redox Behavior and IR Spectroelectrochemistry ……………. 23 2.2.5 Biologically Relevant Reactivity ……………………………. 25 2.3 Summary and Conclusions ………………………………………… 30 2.4 Experimental Section ……………………………………………… 31 2.4.1 Chemicals …………………………………………................. 31 2.4.2 Instrumentation/Spectroscopy ………………………………. 32 vi 2.4.3 Syntheses ……………………………………………………. 33 2.4.4 Reactivity Studies …………………………………................ 35 2.4.4.1 Reactions of the (por)Fe(η2-ON(R)NO) Complexes (por = OEP, T(p-OMe)PP; R = t-Bu, Ph) with 1-MeIm ……. 35 2.4.4.2 Reactions of the (por)Fe(η2-ON(t-Bu)NO) complexes (por = OEP, TPP) with NO gas ………………...................... 36 2.4.4.3 Protonation of the (por)Fe(η2-ON(R)NO) complexes ……... 36 2.4.4.4 Chemical oxidation of (TPP)Fe(η2-ON(t-Bu)NO) ................ 37 2.4.5 Magnetic Susceptibility and EPR Measurements …................ 38 2.4.5.1 Magnetic measurements …………………………………… 38 2.4.5.2 Electron paramagnetic resonance spectroscopy …………… 39 2.4.6 Electrochemistry and Spectroelectrochemistry ……………… 40 2.4.7 X-ray Crystallography ……………………………………….. 41 2.5 References ………………………………………………................. 45 Chapter 3 Hydride Attack on a Coordinated Ferric Nitrosyl: Experimental and Theoretical Evidence for the Formation of Fe−HNO vs. (NO)Fe−H complexes ……………………... 50 3.1 Introduction ………………………………………………………... 50 3.2 Results and Discussion …………………………………………….. 52 3.2.1 Synthesis and Spectroscopy of the Six-coordinate {FeNO}6 Precursors …………………………………………………… 52 3.2.2 Molecular Structures of the {FeNO}6 Derivatives …………... 58 3.2.3 Reactions of the Six-coordinate {FeNO}6 Complexes with Hydride to Form the Elusive FeHNO Derivatives …………… 64 3.2.3.1 Formation of Fe−HNO complexes ………………………... 65 vii 3.2.3.2 DFT calculations for the hydride attack at the coordinated NO moiety ………………………….................................... 71 3.2.3.3 Decomposition pathways of (por)Fe(HNO)(L) …………… 75 3.2.3.4 Reactions of (por)Fe(HNO)(L) with external NO ………… 78 3.2.4 Reactions of the Five-coordinate {FeNO}6 Complexes with Hydride ……………………………………………………… 82 3.2.4.1 Formation of the Fe−H derivative …………………………. 82 3.2.4.2 DFT calculations for the Fe(N−H)O versus (NO)Fe−H bond formations …………………………………………………. 84 3.3 Summary and Conclusion …………………………………………. 87 3.4 Experimental Section ………………………………........................ 89 3.4.1 Chemicals …………………………………………................. 89 3.4.2 Instrumentation/Spectroscopy ………………………………. 90 3.4.3 Syntheses ……………………………………………………. 91 3.4.3.1 Preparation of the six-coordinate [(por)Fe(NO)(L)]OTf complexes …………………………………………………. 91 3.4.3.2 Preparation of five-coordinate [(OEP)Fe(NO)]OTf ……….. 94 3.4.4 Reactions of the Six-coordinate {FeNO}6 Complexes with Hydride ………………………………………........................ 94 3.4.4.1 Reactions of the six-coordinate [(por)Fe(NO)(L)]OTf complexes with hydride to form (por)Fe(HNO)L derivatives (por = OEP, PPDME, TTP; L = 5-MeIm, 1-MeIm, Im) ……. 94 3.4.4.2 Reactions of the (OEP)Fe(HNO)(5/1-MeIm) complexes with external NO ……………………................................... 96 3.4.5 Reactions of the Five-coordinate {FeNO}6 Complexes with Hydride ……………………………………………………… 97 3.4.6 X-ray Crystallography ……………………………………….. 98 3.4.7 Density Functional Theory (DFT) Calculations ……………... 100 viii 3.5 References ………………………………………………................. 102 Chapter 4 Nucleophilic Reaction on a Coordinated Nitrosyl Ligand to Generate RNO Compounds ………………………………… 107 4.1 Introduction ………………………………………………………... 107 4.2 Results and Discussion …………………………………………….. 109 4.2.1 Reactions of the Six-coordinate {MNO}6 (M = Fe, Ru) Precursors with C−based nucleophiles ………………………. 109 4.2.1.1 Nitrogen−carbon and Fe−carbon bond-forming reactions … 109 4.2.1.2 Nitrogen−carbon bond formation from the reactions of the 6 six-coordinate {RuNO} compounds with C-based nucleophiles ……………………………………………….. 117 4.2.2 Nitrogen−nitrogen Bond-forming Reactions of the Six- 6 coordinate {MNO} (M = Fe, Ru) Precursors with N-based Nucleophiles ………………………………………………… 119 4.3 Summary and Conclusion …………………………………………. 123 4.4 Experimental Section ……………………………………………… 123 4.4.1 Chemicals …………………………………………................. 124 4.4.2 Instrumentation/Spectroscopy ………………………………. 125 4.4.3 Syntheses ……………………………………………………. 125 4.4.3.1 Preparation of [(OEP)Fe(NO)(L)]OTf (L = 5-MeIm, (1); 1-MeIm, (2)) …………………………… 125 4.4.3.2 Preparation of [(OEP)Ru(NO)(L)]BF4 (L = 5-MeIm, 1-MeIm ) ……………………………………. 125 4.4.4 Reactivity Studies …………………………………................ 126 4.4.4.1 Reactions of the [(OEP)Fe(NO)(L)]OTf compounds − − (L = 5-MeIm, 1-MeIm) with Ph (Ph = PhLi, PhMgCl, ZnPh2) ……………………………………………………... 126 ix 4.4.4.2 Reactions of [(OEP)Ru(NO)(L)]OTf 129 (L = 5-MeIm, 1-MeIm) with PhLi …………………………. 4.4.4.3 Reactions of [(OEP)M(NO)(5-MeIm)]X (M = Fe, Ru; X = − − OTf , BF4 ) with NaN3 …………………………………….. 131 4.4.5 X-ray Crystallography …………………………….................. 132 4.5 References ………………………………………………................. 134 x List of Tables Table 2.1 Selected bond lengths (Å), bond angles (°) for 1 and 2•(CH2Cl2) ………………………………………………...... 18 Table 2.2 Structural data for 2-O,O liganded iron(III) porphyrins …… 19 Table 2.3 Crystallographic collection and refinement parameters …...... 44 Table 3.1 Vibrational and absorption spectral data for