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[Fefe] Hydrogenase Active Site Model Complexes Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 599 Synthetic [FeFe] Hydrogenase Active Site Model Complexes LENNART SCHWARTZ ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 UPPSALA ISBN 978-91-554-7404-1 2009 urn:nbn:se:uu:diva-9548 ! " #$ %& ' ' ' ( ) * + , ) -+. ) #$) - / 0 1 2 - ! 3 ) 2 ) &$$) 44 ) ) 5-67 $849$9&&989) / 091 :1 ; . . # ' ' ' ) + ' . ' ') 5 ' / 091 + . + < ' # 9 ) * ' ' / :=9 ;:3>; :(! ; 0 : @ . ; + + # ? # ' . ) A ' ' ) * + ' ' . 9 ) 5 + + . ) 5 . ' ) * ' + '' ) 5 ' 9+ + + < 9 ) * + A + + 9 ' 9 ' ) 5 ' '' 9 :5;9 :55; + . &7 + ,(B9 ' + + ' ' ' / 0 ) ' ! " # $ %&' ()*%+&, C -+. #$ 5--7 "&9"# 5-67 $849$9&&989 % %%% 9$&4 : %DD )A)D E @ % %%% 9$&4; Till mamma och pappa ”Aaaghrrrh!” Laban List of Publications This thesis is based on the following publications, which are referred to in the text by the Roman numerals I-VI. I Iron hydrogenase active site mimic holding a proton and a hydride. Schwartz, Lennart; Eilers, Gerriet; Eriksson, Lars; Gogoll, Adolf; Lomoth, Reiner; Ott, Sascha. Chemical Communications, 2006, (5), 520-522. II Ligand versus metal protonation of an iron hydrogenase actives site mimic. Eilers, Gerriet; Schwartz, Lennart; Stein, Matthias; Zampella, Giuseppe; de Gioia, Luca; Lomoth, Reiner; Ott, Sascha. Chemistry –A European Journal, 2007, (13), 7075-7084. III Facilitated hydride binding in an Fe-Fe hydrogenase active-site biomimic revealed by X-ray absorption spectroscopy and DFT calculations. Löscher, Simone; Schwartz, Lennart; Ott, Sascha; Haumann, Michael. Inorganic Chemistry, 2007, (46), 11094-11105. IV Dynamic ligation at the first amine-coordinated iron hydrogenase active site mimic. Schwartz, Lennart; Ekström, Jesper; Lomoth, Reiner; Ott, Sascha. Chemical Communications, 2006, (40), 4206-4208. V Tuning the electronic properties of Fe2(-arenedithiolate) (CO)6-n(PMe3)n (n = 0, 2) complexes related to the [FeFe] hydrogenase active site. Schwartz, Lennart; Singh, Pradyumna S.; Eriksson, Lars; Lomoth, Reiner; Ott, Sascha. Comptes Rendus Chemie, 2008, (11), 875-889. VI Influence of an electron-deficient bridging o-carborane on the electronic properties of an [FeFe] hydrogenase active site model. Schwartz, Lennart; Eriksson, Lars; Lomoth, Reiner; Teixidor, Francesc; Viñas, Clara; Ott, Sascha. Dalton Transactions, 2008, (18), 2379-2381. The publications are printed with the kind permission from the publishers. Contribution Report Paper I-III Contributed to the formulation of the research problem, performed all synthetic work, contributed to the characterization, prepared samples for the XAS experiments, made contribution to the interpretations of the results and to the writing of the manuscripts. Paper IV Major contribution to the formulation of the research problem, made all experimental work (except X-ray crystallography and FTIR-spectroelectrochemistry), made major contribution to the interpretations of the results and to the writing of the manuscript. Paper V Major contribution to the formulation of the research problem, made all synthetic work and characterization, made the initial voltammetric studies, performed all of the attempted catalysis experiments, made major contribution to the interpretations of the results and to the writing of the manuscript. Paper VI Major contribution to the formulation of the research problem, made all experimental work, made major contribution to the interpretations of the results and contributed to the writing of the manuscript. Chapter 5 Major contribution to the formulation of the research problem, made all synthetic work concerning the synthesis of the iron complexes. Chapter 6 Major contribution to the formulation of the research problem, majority of the experimental work (synthesis, characterization by NMR and IR, cyclic voltammetry, in situ IR experiments and EPR samples), made major contributions in coordinating a multi- disciplinary project. Abbreviations adt 2-azapropane-1,3-dithiolate or azadithiolate AcOH acetic acid bdt benzene-1,2-dithiolate bpy 2,2’-bipyridine cdt carborane-1,2-dithiolate CV Cyclic Voltammetry dba dibenzylideneacetone dqp 2,6-di(8’quinolinylpyridine) DCM dichloromethane DFT Density Functional Theory DPV Differential Pulse Voltammetry ENDOR Electron Nuclear Double Resonance Epa anodic peak potential Epc cathodic peak potential EPR Electron Paramagnetic Resonance edt ethane-1,2-dithiolato EXAFS Extended X-Ray Absorption Fine Structure Fc ferrocene FTIR Fourier Transform Infrared Spectroscopy GC Gas Chromatography H2ases Hydrogenases HBr hydrobromic acid HCl hydrochloric acid HClO4 perchloric acid HOTf triflic acid = trifluoromethanesulfonic acid HOTs p-toluenesulfonic acid HYSCORE Hyperfine Sublevel Correlation Spectroscopy ip,a anodic peak current ip,c cathodic peak current IR Infrared Spectroscopy LUMO Lowest Unoccupied Molecular Orbital Me methyl MeCN acetonitrile NMR Nuclear Magnetic Resonance ORTEP Oak Ridge Thermal Ellipsoid Plot pdt propane-1,3-dithiolate Pr propyl SCE Saturated Calomel Electrode = 380 mV vs. Fc/Fc+ S-Phos 2-Dicyclohexylphosphino-2',6'-dimethoxybiphenyl SEC Spectroelectrochemistry TBA tert-butylamine TEA triethanolamine THF tetrahydrofuran TLC Thin Layer Chromatography TMEDA N,N,N',N'-Tetramethylethylenediamine tpy 2,2’:6’,2,’’-terpyridine XAS X-ray Absorption Spectroscopy XANES X-ray Absorption Near Edge Structure X-phos 2-Dicyclohexylphosphino-2a,4a,6a-triisopropylbiphenyl Table of Contents 1 Introduction .........................................................................................11 1.1 General........................................................................................11 1.2 The Concept of Artificial Photosynthesis ...................................12 1.2.1 Proton Reduction Catalysts....................................................13 1.3 Hydrogenases..............................................................................14 1.3.1 General...................................................................................14 1.3.2 [FeFe] Hydrogenases .............................................................15 1.4 Synthetic Model Complexes of the [FeFe] Hydrogenase [2Fe]H Subsite.........................................................................................17 1.4.1 General Synthetic Routes.......................................................17 1.4.2 Design of Model Complexes .................................................18 1.5 Experimental Methods................................................................20 1.5.1 General...................................................................................21 1.5.2 Infrared Spectroscopy............................................................21 1.5.3 Electrochemistry ....................................................................23 2 Mimicking the Dibasic Properties of the [FeFe] Hydrogenase [2Fe]H Subsite (paper I-III) ............................................................................26 2.1 Introduction.................................................................................26 2.2 Synthesis .....................................................................................27 2.3 Characterization of the Protonation States..................................28 2.4 Electrochemistry and Electrochemical Proton Reduction...........32 2.5 Conclusions.................................................................................33 3 Mimicking the Labile Ligand in the [FeFe] Hydrogenase [2Fe]H Subsite (paper IV)...............................................................................35 3.1 Introduction.................................................................................35 3.2 Synthesis .....................................................................................36 3.3 Electrochemistry and Infrared Spectroscopy ..............................37 3.4 An Analogue Bearing the Azadithiolate Functionality (Unpublished) .............................................................................41 3.5 Conclusions.................................................................................41 4 Tuning the Electronic Properties of [FeFe] Hydrogenase [2Fe]H Subsite Model Complexes (Papers V and VI)....................................43 4.1 Introduction.................................................................................43 4.2 Synthesis and Characterization ...................................................44 4.3 Electrochemistry .........................................................................50 4.3.1 Electrochemical Behaviour....................................................50 4.3.2 Electrochemical Proton Reduction ........................................53 4.4 Conclusions.................................................................................55 5 Towards Light-driven Electron Transfer and Hydrogen Generation from an [FeFe] Hydrogenase Active Site Mimic Covalently Linked to a Ruthenium Photosensitizer ..............................................................57 5.1 Introduction.................................................................................57
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