Vanadium and Molybdenum Complexes with Amino Acid Functionalized Ligands DISSERTATION zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) vorgelegt dem Rat der Chemisch-Geowissenschaftlichen Fakult¨at der Friedrich-Schiller Universit¨at Jena von Food Chemist Manjola Mancka geboren am 17.04.1978 in Devoll, Albania Gutachter 1. Prof. Dr. Winfried Plass 2. Prof. Dr. Matthias Westernhausen Tag deroffentlichen ¨ Verteidigung: October 18th 2006 For my beloved parents and my Family Acknowledgements • I would like to express my heartfelt gratitude to my supervisor Prof. Dr. Winfried Plass for giving me the opportunity to work in this interesting field, I thank him for support, advises and guidance. • I also thank to Dr. Axel Buchholz, for many valuable suggestions, for much help in the single crystal analysis, and for his help in the arrangement of the thesis. • I am grateful to our research group with whom I had the pleasure of working, for their friendship, helpful discussions, and the good co-operative atmosphere. I also thank to my colleague Arne Roth for helping me in solving LATEXproblems. I would like to thank Ines Seidel for many valuable discussions about the kinetic experiments. • I moreover thank all Technical assistants of the Institut f¨ur Anorganische und Ana- lytische Chemie (IAAC) and NMR department for analyses of the samples: Dr. Popitz, Frau Sch¨onau und Frau Heineck (MS), Frau Rambach und Dr. Friedrich (NMR, EPR), Frau Lentvogt und Frau Sch¨onfeld (CHN). • Many thanks to Lotte Neupert for the HPLC measurements. • I am especially pleased to acknowledge Dr. Helmar G¨orls for measuring my X-ray crystal structures. • Finally, I would like to thank my parents Seri and Hava, my sisters Anila and Amoleza, as well as my brother Ardi, especially my husband, Anton, for their con- tinued moral support, patience and encouragement. They are the most important people in my life and they have been with me every step of the way. Contents 1 Introduction 11 1.1Historyofvanadium............................. 11 1.2Vanadiumhaloperoxidases.......................... 13 1.3Phosphate-Vanadate-Analogy........................ 19 1.4 Structural models for vanadium-dependent haloperoxidases................................ 20 1.5Designofnewligandsystem......................... 22 1.6Historyandoccurrenceofmolybdenum................... 23 2 V(v)-Complexes with Boc-L-α-amino acid ligands 27 2.1SynthesisandReactions........................... 28 2.2Structuralcharacterization.......................... 31 2.3SpectroscopicCharacterization........................ 36 2.4Reactivityofthecomplexes......................... 39 2.4.1 BrominationreactionofTMB/MCD................ 39 2.4.2 Catalytic oxidation of sulfides catalyzed by cis-dioxovanadium(v)complexes.................. 40 2.5Conclusions.................................. 44 2.6ExperimentalPart.............................. 45 2.6.1 Synthesis of the Schiff base ligands with Boc-L-α-serine residue . 45 2.6.2 Synthesis of N -salicylidene-Boc-L-α-histidine-hydrazide (HsalhyBochis)............................ 47 2.6.3 Synthesis of the Schiff base ligands with Boc-L-α-tryptophanresidue..................... 48 5 6CONTENTS 2.6.4 Synthesis of the Schiff base ligands with Boc-L-α-phenylalanineresidue.................... 50 2.6.5 Synthesis of cis-dioxovanadium(v)-complexes with Boc-L-α-serine residueligands............................ 53 2.6.6 Synthesis of cis-dioxovanadium(v)-complexes with Boc-L-α-histidine residueligands............................ 56 2.6.7 [VO2(HsalhyBochis)](5)....................... 56 2.6.8 Synthesis of cis-dioxovanadium(v)-complexes with Boc-L-α-tryptophan residueligands............................ 57 2.6.9 Synthesis of cis-dioxovanadium(v)-complexes with Boc-L-α-phenylalanine residueligands............................ 58 2.6.10 Synthesis of monooxovanadium complexes with phenylalanine Schiff baseligands.............................. 62 2.6.11CatalyticoxidativebrominationofTMB/MCD.......... 63 2.6.12Generalprocedureforpreparationofchiralsulfoxides:....... 64 3 V(v)-complexes with free L-α-amino acid ligands 65 3.1SynthesisandReactions........................... 66 3.2Structuralcharacterization.......................... 71 3.2.1 Complexeswithphenylalanineresidue(18)............. 71 3.2.2 Complexeswithtyrosineresidue(20aand20b).......... 76 3.2.3 Comparisonofthestructures18and20b.............. 81 3.2.4 Unprecedented complex 21 . ................... 81 3.3SpectroscopicCharacterization........................ 88 3.4Reactivityofthecomplexes......................... 92 3.4.1 Oxidative bromination of 1,3,5-trimethoxybenzene/monochlordimedone........... 92 3.4.2 Oxidation of sulfides catalyzed by cis-dioxovanadium complexes withfreeaminoacidfunctionalizedligands............. 94 3.4.3 Spectrophotometrictitration..................... 95 3.5Conclusions.................................. 96 CONTENTS 7 3.6ExperimentalSection............................. 97 3.6.1 Synthesis of the Schiff base ligands with L-α-leucine residue . 97 3.6.2 Synthesis of the Schiff base ligands with L-α-phenylalanine residue 99 3.6.3 Synthesis of the Schiff base ligands with L-α-tyrosine residue . 103 3.6.4 Synthesis of cis-dioxovanadium(v)-complexes with L-α-leucine residue ligands................................. 107 3.6.5 Synthesis of cis-dioxovanadium(v)-complexes with L-α-phenylalanine residueligands............................ 109 3.6.6 Synthesis of cis-dioxovanadium(v)-complexes with L-α-tyrosine residue ligands................................. 111 3.6.7 Unprecedented obtaining complexes ................. 114 3.6.8 CatalyticoxidativebrominationofTMB/MCD.......... 117 3.6.9 Catalyticoxidationofmethylphenylsulfide:............ 118 4 V(v)-complexes with L-β-alanine ligands 119 4.1 V-complexes with Boc-L-β-alanine..................... 120 4.1.1 SpectroscopicCharacterization................... 121 4.1.2 Reactivityofthecomplexes..................... 123 4.2 Complexation studies using free β-alanineligand.............. 126 4.3Conclusions.................................. 127 4.4Experimentalpart.............................. 128 4.4.1 Synthesis of Schiff base ligand with Boc-L-β-alanine........ 128 4.4.2 Synthesis of vanadium complexes with Boc-L-β-alanine...... 130 4.4.3 Synthesis of Schiff base ligand with L-β-alanine.......... 131 4.4.4 Attempted synthesis of vanadium complexes with L-β-alanine . 133 4.4.5 CatalyticoxidativebrominationofTMB/MCD.......... 134 4.4.6 Catalyticoxidationofmethylphenylsulfide............ 134 5 Mo(VI)-complexes with Boc-amino acid ligands 136 5.1 Molecular structure of complex 36 ..................... 137 5.2SpectroscopicCharacterization........................ 140 5.3Sulfoxidationreaction............................. 141 8CONTENTS 5.4Conclusions.................................. 143 5.5Experimentalpart.............................. 144 5.5.1 [MoO2(salhyBocser)](31)...................... 144 5.5.2 [MoO2(salhyBoctrp)]·Et2O(32)................... 145 5.5.3 [MoO2(salhyBocphe)](33)...................... 146 5.5.4 [MoO2(BrsalhyBocphe)](34)..................... 147 5.5.5 [MoO2(MesalhyBocphe)](35).................... 147 5.5.6 [MoO2(salhyBocala)(MeOH)]·2MeOH(36)............. 148 5.5.7 Catalyticoxidationofmethylphenylsulfide:............ 149 6 Mo(VI)-complexes with free amino acid ligands 151 6.1Structuralcharacterization.......................... 152 6.1.1 Mo-complexwithleucineresidue(37)................ 152 6.1.2 Mo-complexwithphenylalanineresidue(39)............ 155 6.1.3 Mo-complexwithtyrosineresidue(42)............... 157 6.2SpectroscopicCharacterization........................ 163 6.3SulfoxidationReaction............................ 164 6.4Conclusions.................................. 166 6.5Experimentalpart.............................. 167 6.5.1 [MoO2(Brsalhyleuacac)(MeOH)](37)................ 167 6.5.2 [MoO2(Mesalhyphe)](38)...................... 167 6.5.3 [MoO2(Mesalhypheacac)(MeOH)]·2MeOH(39)........... 168 6.5.4 [MoO2(Brsalhyphe)(MeOH)]·H2O(40)............... 169 6.5.5 [MoO2(Mesalhytyr)]·2H2O(41)................... 169 6.5.6 [MoO2(Mesalhytyracac)(MeOH)]·2MeOH·Et2 O(42)........ 170 6.5.7 Catalyticoxidationofmethylphenylsulfide............ 171 7 Summary 172 8 Characterization techniques 180 8.1Elementalanalyses.............................. 180 8.2NMRspectroscopy.............................. 180 CONTENTS 9 8.3Massspectrometry.............................. 180 8.4Infraredspectroscopy............................. 181 8.5UV-Vismeasurements............................ 181 8.6HPLCanalyses................................ 181 8.7Crystalstructureanalyses.......................... 181 8.8 General Remarks: ............................. 182 I Crystallographic data 183 II Abbreviations 193 10 CONTENTS Chapter 1 Introduction 1.1 History of vanadium Vanadium was first discovered in 1801 by Andr´es Manuel del Rio, a Spanish professor of mineralogy working in Mexico City. He originally named the element panchromium after the various color of its salts, but later renamed it erythronium because of the red color generated upon heating. Unfortunately, del Rio lost confidence in his discovery, thinking that he had found the element chromium, which had recently been discovered by the Frenchman Fourcroy. Vanadium was rediscovered in 1831 by the Swede Nils Gabriel Sefstr¨om. Its present name is derived from the Vanadis, the goddess of love and beauty of Norse mythology. Metallic vanadium was not isolated until 1867 when Sir Henry Enfield Roscoe, Professor of Chemistry at Owens College (later the University