© 2015 Joseph Alexander Macor ON THE COORDINATION CHEMISTRY OF PENTAVALENT (!4, "5) PHOSPHORUS COMPOUNDS BY JOSEPH ALEXANDER MACOR DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry in the Graduate College of the University of Illinois at Urbana-Champaign, 2015 Urbana, Illinois Doctoral Committee: Professor Gregory S. Girolami, Chair Professor Scott E. Denmark Assistant Professor Alison R. Fout Professor Yi Lu !"#$%&'$( ( #$%&'(!)*&+,-.&/!0,1$/! 2&',/34&-3!$5!6(&4"%3/7! 8-"9&/%"37!$5!:**"-$"%!,3!8/;,-,<6(,4',"=->!?@AB! C/&=$/7!DE!C"/$*,4">!).9"%$/! ! The work described herein details the synthesis of a variety of pentavalent organophosphorus compounds and their applications as ligands to address important problems in coordination chemistry. This research encompasses two main themes: (1) the asymmetric synthesis of enantiopure !-alkylbenzylphosphonic acids, and the use of these compounds to prepare homochiral vanadium diphosphonate materials that can serve as heterogeneous catalysts for the asymmetric epoxidation of allylic alcohols, and (2) the design and synthesis of novel heterocyclic dithiophosphinic acids and exploration of their coordination chemistry with the f-elements, with the ultimate goal of better understanding the properties that dictate selectivity in Ln/An extractions in the context of nuclear fuel reprocessing. Enantiopure (R)-BINOLato benzylphosphonate is easily and inexpensively prepared, and is stable to air and moisture. Deprotonation with n-butyllithium followed by addition of a methyl, ethyl, allyl, or benzyl halide electrophile at -78 °C affords (R)-BINOLato (R)-1-alkylbenzylphosphonates in good yields and excellent diastereoselectivities. Removal of the chiral auxiliary is best accomplished in a two step procedure: cesium fluoride promoted transesterification to the dimethyl ! ""! phosphonate ester, followed by acidic hydrolysis to the corresponding phosphonic acid. This sequence affords (R)-1-alkylbenzyl-phosphonic acids in high yield and optical purity. This technique can be extended to the synthesis of chiral diphosphonic acids containing naphthalene backbones. These ligands, along with their achiral analogues, react with VO2+ to generate vanadyl diphosphonate materials. These products are insoluble in organic solvents and have a layered architecture as judged by powder X-ray diffraction. These compounds are the first examples of homochiral polymers containing diphosphonate linkages, and exhibit exceptional catalytic activity for the heterogeneous chemoselective epoxidation of allylic alcohols when tert-butyl hydroperoxide is employed as a stoichiometric oxidant. With the homochiral catalysts, the enantioselectivity is modest, but apparent (e.r. " 3:2). Synthetic methodology has also been developed that affords novel heterocyclic 2,2#-biphenylenedithiophosphinic acids, which contain 5-membered dibenzophosphole rings. These new compounds have been fully characterized by conventional techniques, as well as by K-edge X-ray absorption spectroscopy in order to elucidate the electronic consequence of rotational restriction about the P– Cipso bonds. Liquid/liquid extraction studies show that these compounds exhibit a ca. 10:1 selectivity for the preferential chelation of 241Am over 154Eu. In addition, homoleptic complexes of Eu3+, Nd3+, U4+, and Np4+ with the 2,2#- biphenylenedithiophosphinate ligand have been prepared and characterized by single crystal X-ray diffraction. ! """! ! ! ! ! ! ! ! “As the true method of knowledge is experiment, the true faculty of knowing must be the faculty which experiences.” !"#$%%$&'"(%&)*"+,-.-/" ! ! ! ! ! ! ! ! ! "9! !"#$%&'()*+($,-. A dissertation is an interesting thing. Specifically, it is often difficult to see the human aspects behind the written work: the long nights spent in lab, the heated arguments with reagent bottles, the immense satisfaction of a ‘spot-to-spot’ reaction, or the nervous anticipation while walking to the NMR lab where promises of novel compounds are whispered in multiplets. The final product looks so much cleaner. That being said, it is even harder to imagine its completion without the overwhelming support of various mentors, colleagues, and friends I have had the fortunate consequence of encountering along this journey. To my advisor Greg Girolami, I am immensely grateful for your guidance, assistance, and the countless scientific conversations that often seemed to completely diverge (in a good way) from what I had originally intended to discuss. I believe you have set me on a path to become precisely the type of scientist I admired when I was younger. I would also like to thank the remainder of my doctoral committee, Scott Denmark, Alison Fout, Yi Lu, and Tom Rauchfuss for all of your advice and constructive criticism. To the past and present Girolami group members, Andrew Dunbar, Luke Davis, Jenny Steele, Noel Chang, Justin Mallek, Peter Sempsrott, Brian Trinh, Tracy Codding, Sumeng Liu, Kaili Zhang, and Chelsea Hadsall, thank you for the beneficial conversations about life and chemistry, and for providing a fantastic work ! 9! environment. I would also like to thank the UIUC SCS staff, namely Marie Keel, Rudy Laufhutte, Beth Eves, Danielle Gray, Jeff Bertke, Dean Olson, Connie Knight, Beth Myler, Stacy Dudzinski, Karen Watson, and Theresa Struss. You have all been extremely helpful and are outstanding at what you do. To my other friends and colleagues, Rob Hicklin, Huy Le, Greg Snapper, Dr. Jonathan Eller, and Dr. Scott Sarfert, I cannot thank you enough for the much needed (and even the occasionally unneeded) distractions from lab. I would wish you all good luck in your future endeavors, but I am certain you will not need it. To my coworkers at Los Alamos (and otherwise unaffiliated New Mexican friends) particularly Angie Olson, Matthias Loble, Justin Cross, Chantal Stieber, and Ralph Zhender, thank you for the enlightening discussions on actinide chemistry and for generally making my time in the desert an enjoyable one. I would also like to thank Stosh Kozimor– I couldn’t have asked for a better advisor, mentor, and friend. Lastly, I would also like to thank my family for their continued and unending love and support. To my Ph.D.-holding chemist relatives Uncle Jack, Aunt Kathy, and Uncle Mike, your advice and encouragement through the years has been invaluable. To my parents Cathy and Jim Macor, it has been a true privilege to call myself your offspring. Thank you for everything. ! ! 9"! "#$%&!'(!)'*+&*+,! 1. General Overview of the Chemistry of Organophosphorus(V) Compounds ……………………………………… 1 1.1 Nomenclature ...……………………………………………………….. 1 1.2 The Nature of the Phosphoryl Bond ...…………………………. 3 1.3 Synthesis and Reactivity of Pentavalent Organophosphorus Compounds …………………...……………. 4 1.3.1 Synthesis …………………………………………………. 4 1.3.2 Reactivity: Applications in Organic Synthesis …….. 9 1.4 Applications of Pentavalent Phosphorus Compounds in Coordination Chemistry ……………………….. 14 1.4.1 Heterogeneous Systems ……………………..…………. 15 1.4.2 Homogeneous Systems ……………………………….... 17 1.5 References ………………………………………………………….. 20 2. Synthesis of Enantiopure Phosphonic Acids with BINOL as a Chiral Auxiliary ……………………………………………. 28 2.1 Background ………………………………………………………… 28 2.2 BINOL as a Stereocontroller …………………………………..... 31 2.3 Asymmetric Phosphonate Alkylation Using BINOL ………… 34 2.3.1 Attachment of the BINOL Auxiliary ………………… 35 2.3.2 Asymmetric Alkylation ………………………………… 35 2.3.3 Removal of the BINOL Auxiliary……………………… 40 2.4 Conclusions and Future Work …………………………………... 47 2.5 Experimental ………………………………………………………. 47 2.6 References ………………………………………………………….. 60 3. Chiral Vanadium Diphosphonates as Heterogeneous Asymmetric Epoxidation Catalysts ……………………………………… 74 ! 9""! 3.1 Background ………………………………………………………… 74 3.2 Prior Art ……………………………………………………………. 78 3.3 Synthesis of Chiral and Achiral Diphosphonic Acid Ligands ……………………………………… 83 3.4 Synthesis of Heterogeneous Vanadium Diphosphonates …… 87 3.5 Catalytic Oxidations with Vanadium Diphosphonates ……… 94 3.6 Conclusions and Future Work …………………………………... 98 3.7 Experimental ………………………………………………………. 98 3.8 References ………………………………………………………….. 119 4. Heterocyclic Dithiophosphinic Acids for the Selective Extraction of Minor Actinides ………………………………… 127 4.1 Background ………………………………………………………… 127 4.2 Prior Art ……………………………………………………………. 134 4.2.1. Dithiophosphinate Extractants ………………………. 134 4.2.2 K-Edge X-ray Absorption Spectroscopy: a Quantitative Probe of Covalency …………………... 135 4.3 Heterocyclic Dithiophosphinate Extractants ………………….. 140 4.3.1 Ligand Synthesis and Characterization …………….. 142 4.3.2 K-Edge X-ray Absorption Spectroscopy ……………… 152 4.3.3 Eu/Am Extraction Experiments ………………………. 154 4.4. Biphenylenedithiophosphinate Complexes of the f-Elements …………………………………………………. 156 4.5 Conclusions and Future Work …………………………………... 169 4.6 Experimental ………………………………………………………. 171 4.7 References ………………………………………………………….. 187 ! "###! /012,(3.4. 5($(31'.67(378(&.%9.,0(./0(+8-,3:.%9.. 63*1$%20%-20%3;-<=>./%+2%;$)-. Although trivalent phosphorus finds many uses in the laboratory, pentavalent phosphorus is far more common (and more important) in the world around us. Its compounds exhibit diverse properties, surpassed only, perhaps, by their potential utility to mankind. This introduction aims to provide general insights into the chemical nature of this class of compounds, and highlights pertinent applications within the context of coordination chemistry. )*)(+,-./'0&$1%.(