Die vorliegende Dissertation beschreibt die Synthese und Charakterisierung von neuartigen perferrocenylierten, cyclischen Komplexen unter Anwendung der Cobalt-vermittelten Cyclomerisierung in Kombination mit einer C-H-Bindungsaktivierung als auch die Bildung von ferrocenylierten Phosphinoalkinid-Komplexen mit Eisen- und Cobaltcarbonylen. Die elektrochemischen Eigenschaften und die Elektronentransfer-prozesse zwischen den terminalen Ferrocenyleinheiten in den unterschiedlichen cyclischen Verbindungen wurden unter Einbeziehung der Struktur/chemischen Zusammensetzung der Brückenbausteine ermittelt. Elf perferrocenylierte, cyclische Komplexe wurden mittels [2+2] bzw. [2+2+2] Cyclomerisierung von 1,4-Diferrocenylbutadiin FcC≡C–C≡CFc (Fc = Fe(η5-C5H4)(η5-C5H5)) unter Verwendung von Dicarbonylcyclopentadienylcobalt Co(η5-C5H5)(CO)2 erhalten. Diese können in drei Gruppen unterteilt werden: (i) Produkte der Cyclodimerisierung mit zusätzlicher Kettenverlängerung, welche Cyclobutadienyl-einheiten als zentrale Brückenbausteine besitzen (3a,b und 4a,b), (ii) Produkte der Cyclodimerisierung mit gleichzeitiger CO-Insertion (6a,b,c und 7), und (iii) Produkte der Cyclotrimerisierung gefolgt von einem Ringschluss durch eine C-H-Bindungsaktivierung (5a,b,c). Die Optimierung der Reaktionsbedingungen wurde zur Ausbeutemaximierung der jeweiligen Verbindungsfamilien durchgeführt. Ein weiterer Teil dieser Forschungsarbeit bezieht sich auf die verschiedenen Reaktionsmuster von (Ferrocenylethinyl)diphenylphosphan- mit zweikernigen Eisen- bzw. Cobaltcarbonylverbindungen in Form von Dieisennonacarbonyl und Dicobaltoctacarbonyl als Reagenzien. Dabei konnten sechs gemischte Carbonyl- und Ferrocenyl-funktionalisierte Phosphinoacetylid-Komplexe mit Eisen(0) und Cobalt(0) erhalten und charakterisiert werden. / The present PhD study focuses on the synthesis and characterization of novel perferrocenylated cyclic complexes utilizing cobalt - mediated cyclomerization in combination with C–H bond activation as well as formation of ferrocenylated phosphino-alkyne compounds with iron and cobalt carbonyls. Electrochemical properties and electron-transfer processes between terminal ferrocenyl units in the diverse cyclic compounds are explored in relation to the chemical composition of the building blocks connecting them. Eleven perferrocenylated cyclic compounds were obtained via [2 + 2] and [2 + 2 + 2] cyclomerization of 1,4-diferrocenylbutadiyne FcC≡C–C≡CFc (Fc = Fe(η5-C5H4)(η5-C5H5)) by the reaction with dicarbonylcyclopentadienylcobalt Co(η5-C5H5)(CO)2. They are subdivided into three groups: (i) products of cyclodimerization with additional chain extension, possessing cyclobutadienyl moieties as a central linkage unit (3a,b and 4a,b), (ii) products of cyclodimerization with consecutive CO insertion (6a,b,c and 7), and (iii) products of cyclotrimerization followed by cycle formation via C–H bond activation (5a,b,c). Optimization of the reaction conditions was made in order to maximize the amount of each group of compounds. Furthermore, another part of this research work focuses on diverse reaction patterns of (ferrocenylethynyl)diphenylphosphane with diironnonacarbonyl and dicobaltocta-carbonyl. Six mixed carbonyl and ferrocenyl-functionalized phospinoalkynyl compounds of iron(0) and cobalt(0) were obtained and characterized.

Die vorliegende Dissertation beschreibt die Synthese und Charakterisierung von neuartigen perferrocenylierten, cyclischen Komplexen unter Anwendung der Cobalt-vermittelten Cyclomerisierung in Kombination mit einer C-H-Bindungsaktivierung als auch die Bildung von ferrocenylierten Phosphinoalkinid-Komplexen mit Eisen- und Cobaltcarbonylen. Die elektrochemischen Eigenschaften und die Elektronentransfer-prozesse zwischen den terminalen Ferrocenyleinheiten in den unterschiedlichen cyclischen Verbindungen wurden unter Einbeziehung der Struktur/chemischen Zusammensetzung der Brückenbausteine ermittelt. Elf perferrocenylierte, cyclische Komplexe wurden mittels [2+2] bzw. [2+2+2] Cyclomerisierung von 1,4-Diferrocenylbutadiin FcC≡C–C≡CFc (Fc = Fe(η5-C5H4)(η5-C5H5)) unter Verwendung von Dicarbonylcyclopentadienylcobalt Co(η5-C5H5)(CO)2 erhalten. Diese können in drei Gruppen unterteilt werden: (i) Produkte der Cyclodimerisierung mit zusätzlicher Kettenverlängerung, welche Cyclobutadienyl-einheiten als zentrale Brückenbausteine besitzen (3a,b und 4a,b), (ii) Produkte der Cyclodimerisierung mit gleichzeitiger CO-Insertion (6a,b,c und 7), und (iii) Produkte der Cyclotrimerisierung gefolgt von einem Ringschluss durch eine C-H-Bindungsaktivierung (5a,b,c). Die Optimierung der Reaktionsbedingungen wurde zur Ausbeutemaximierung der jeweiligen Verbindungsfamilien durchgeführt. Ein weiterer Teil dieser Forschungsarbeit bezieht sich auf die verschiedenen Reaktionsmuster von (Ferrocenylethinyl)diphenylphosphan- mit zweikernigen Eisen- bzw. Cobaltcarbonylverbindungen in Form von Dieisennonacarbonyl und Dicobaltoctacarbonyl als Reagenzien. Dabei konnten sechs gemischte Carbonyl- und Ferrocenyl-funktionalisierte Phosphinoacetylid-Komplexe mit Eisen(0) und Cobalt(0) erhalten und charakterisiert werden.:Table of contents Bibliografische Beschreibung und Referat iii Abstract iv Ort und Zeitraum der Durchführung v Widmung vi Präambel vii List of Abbreviations xii CHAPTER A Introduction 15 References 16 CHAPTER B State of Knowledge 19 1 (Spectro)electrochemical studies of mixed-valent transition metal complexes. Theoretical background 19 1.1 Mixed-valent compounds – classification 20 1.2 Spectroelectrochemistry 21 1.3 Electrochemistry 25 2 (Di)ferrocenylalkynes – synthesis and reactions 28 2.1 1,4-Diferrocenylbutadiyne 29 2.2 Other (poly)ferrocenyl substituted alkyne derivatives 35 3 Dicarbonylcyclopentadienylcobalt – [2+2] and [2+2+2] cyclo-addition reactions 37 3.1 [2+2] and [2+2+2] cycloaddition – cyclobutadiene, cyclopentadienone, benzene and pyridine based systems 38 3.2 Mechanism of [2+2] and [2+2+2] cycloaddition/cyclization and [2+2] cycloaddition/cyclization with CO insertion mediated by CoCp(CO)2 40 4 Chelation-assisted C–H bond activation mediated by cobalt species 42 5 Phosphinoalkynes and their reaction with iron and cobalt carbonyls 44 5.1 Mechanism of the P–C(sp) bond cleavage in phosphinoalkynes 48 6 Complexes setup by (ferrocenylethynyl)diphenylphosphane 50 References 56 CHAPTER C Multiferrocenyl Cobalt-Based Sandwich Compounds 64 1 Introduction 64 2 Results and Discussion 65 2.1 Synthesis and Characterization 65 2.2 Solid-State Structures 71 2.3 Electrochemistry 73 2.4 Spectroelectrochemistry 76 3 Experimental Section 79 3.1 Instrumentation 79 3.2 General Conditions 81 3.3 Reagents 81 3.4 General Procedure - Reaction of 1 with 2 81 3.4.1 Compound 3a 82 3.4.2 Compound 3b 82 3.4.3 Compound 4b 83 3.4.4 Compound 5c 83 3.4.5 Compound 6a 84 3.4.6 Compound 6b 84 3.4.7 Compound 6c 85 3.4.8 Compound 7 85 4 Supporting information 86 5 References 86 CHAPTER D Combining Cobalt-Assisted Alkyne Cyclotrimerization and Ring Formation through C–H Bond Activation: A “One-Pot” Approach to Complex Multimetallic Structures 91 1 Introduction 91 2 Results and Discussion 92 3 Experimental Section (Supporting information) 98 3.1 General Information 98 3.2 Starting Materials 98 3.3 Synthesis of 3a and 3b from 2 99 3.3.1 Complex 3a: 99 3.3.2 Complex 3b: 100 3.4 Synthesis of 9a and 9b from 1-Ferrocenylethynyl-2-Ferrocenyl Benzene (8) 101 3.4.1 Synthesis of 1-Bromo-2-Ferrocenylethynyl Benzene (7) 101 3.4.2 Synthesis of 1-Ferrocenylethynyl-2-Ferrocenyl Benzene (8) 102 3.4.3 Synthesis of 9a and 9b from 8 103 3.5 Synthesis of 3a and 3b from 1,3,5-Triethynylferrocenyl-2,4,6-Triferrocenyl Benzene (4) 105 3.5.1 Synthesis of 1,3,5-Trichloro-2,4,6-Triethynylferrocenyl Benzene (12) 105 3.5.2 Synthesis of 1,3,5-Triethynylferrocenyl-2,4,6-Triferrocenyl Benzene (4) 105 3.5.3 Synthesis of 3a and 3b from 4 106 4 Supporting information 107 4.1 Spectroelectrochemistry of 3a,b 107 4.2 Conversion of Isomer 9a to 9b – Electrochemical and Chemical oxidation 109 4.3 Chemical oxidation experiment 110 5 References 111 CHAPTER E Coordination Behavior of (Ferrocenylethynyl)diphenyl-phosphane Towards Binuclear Iron and Cobalt Carbonyls 114 1 Introduction 114 2 Results and Discussion 115 3 Experimental Section 126 3.1 Instrumentation 126 3.2 General 128 3.3 Reagents 128 3.4 Synthesis of 4 128 3.5 Synthesis of 4, 5 and 6 129 3.6 Synthesis of 6 by reacting 4 with 2 131 3.7 Synthesis of 7 and 8 131 3.8 Synthesis of 8 from 1 with 3 132 3.9 Synthesis of 9 in the reaction of 7 with 2 133 3.10 Synthesis of 9 in the reaction of 4 with 3 133 4 Electronic Supplementary Material (Supporting information) 134 5 References 134 CHAPTER F Summary 139 1 Conclusions of Chapter C (Appendix A) 139 2 Conclusions of Chapter D (Appendix B) 141 3 Conclusions of Chapter E (Appendix C) 142 Appendix 145 1 Appendix D (Chapter C) 145 2 Appendix E (Chapter D) 146 3 Appendix F (Chapter E) 147 Curriculum Vitae 150 Publications 152 Acknowledgements 154 Selbstständigkeitserklärung 155 / The present PhD study focuses on the synthesis and characterization of novel perferrocenylated cyclic complexes utilizing cobalt - mediated cyclomerization in combination with C–H bond activation as well as formation of ferrocenylated phosphino-alkyne compounds with iron and cobalt carbonyls. Electrochemical properties and electron-transfer processes between terminal ferrocenyl units in the diverse cyclic compounds are explored in relation to the chemical composition of the building blocks connecting them. Eleven perferrocenylated cyclic compounds were obtained via [2 + 2] and [2 + 2 + 2] cyclomerization of 1,4-diferrocenylbutadiyne FcC≡C–C≡CFc (Fc = Fe(η5-C5H4)(η5-C5H5)) by the reaction with dicarbonylcyclopentadienylcobalt Co(η5-C5H5)(CO)2. They are subdivided into three groups: (i) products of cyclodimerization with additional chain extension, possessing cyclobutadienyl moieties as a central linkage unit (3a,b and 4a,b), (ii) products of cyclodimerization with consecutive CO insertion (6a,b,c and 7), and (iii) products of cyclotrimerization followed by cycle formation via C–H bond activation (5a,b,c). Optimization of the reaction conditions was made in order to maximize the amount of each group of compounds. Furthermore, another part of this research work focuses on diverse reaction patterns of (ferrocenylethynyl)diphenylphosphane with diironnonacarbonyl and dicobaltocta-carbonyl. Six mixed carbonyl and ferrocenyl-functionalized phospinoalkynyl compounds of iron(0) and cobalt(0) were obtained and characterized.:Table of contents Bibliografische Beschreibung und Referat iii Abstract iv Ort und Zeitraum der Durchführung v Widmung vi Präambel vii List of Abbreviations xii CHAPTER A Introduction 15 References 16 CHAPTER B State of Knowledge 19 1 (Spectro)electrochemical studies of mixed-valent transition metal complexes. Theoretical background 19 1.1 Mixed-valent compounds – classification 20 1.2 Spectroelectrochemistry 21 1.3 Electrochemistry 25 2 (Di)ferrocenylalkynes – synthesis and reactions 28 2.1 1,4-Diferrocenylbutadiyne 29 2.2 Other (poly)ferrocenyl substituted alkyne derivatives 35 3 Dicarbonylcyclopentadienylcobalt – [2+2] and [2+2+2] cyclo-addition reactions 37 3.1 [2+2] and [2+2+2] cycloaddition – cyclobutadiene, cyclopentadienone, benzene and pyridine based systems 38 3.2 Mechanism of [2+2] and [2+2+2] cycloaddition/cyclization and [2+2] cycloaddition/cyclization with CO insertion mediated by CoCp(CO)2 40 4 Chelation-assisted C–H bond activation mediated by cobalt species 42 5 Phosphinoalkynes and their reaction with iron and cobalt carbonyls 44 5.1 Mechanism of the P–C(sp) bond cleavage in phosphinoalkynes 48 6 Complexes setup by (ferrocenylethynyl)diphenylphosphane 50 References 56 CHAPTER C Multiferrocenyl Cobalt-Based Sandwich Compounds 64 1 Introduction 64 2 Results and Discussion 65 2.1 Synthesis and Characterization 65 2.2 Solid-State Structures 71 2.3 Electrochemistry 73 2.4 Spectroelectrochemistry 76 3 Experimental Section 79 3.1 Instrumentation 79 3.2 General Conditions 81 3.3 Reagents 81 3.4 General Procedure - Reaction of 1 with 2 81 3.4.1 Compound 3a 82 3.4.2 Compound 3b 82 3.4.3 Compound 4b 83 3.4.4 Compound 5c 83 3.4.5 Compound 6a 84 3.4.6 Compound 6b 84 3.4.7 Compound 6c 85 3.4.8 Compound 7 85 4 Supporting information 86 5 References 86 CHAPTER D Combining Cobalt-Assisted Alkyne Cyclotrimerization and Ring Formation through C–H Bond Activation: A “One-Pot” Approach to Complex Multimetallic Structures 91 1 Introduction 91 2 Results and Discussion 92 3 Experimental Section (Supporting information) 98 3.1 General Information 98 3.2 Starting Materials 98 3.3 Synthesis of 3a and 3b from 2 99 3.3.1 Complex 3a: 99 3.3.2 Complex 3b: 100 3.4 Synthesis of 9a and 9b from 1-Ferrocenylethynyl-2-Ferrocenyl Benzene (8) 101 3.4.1 Synthesis of 1-Bromo-2-Ferrocenylethynyl Benzene (7) 101 3.4.2 Synthesis of 1-Ferrocenylethynyl-2-Ferrocenyl Benzene (8) 102 3.4.3 Synthesis of 9a and 9b from 8 103 3.5 Synthesis of 3a and 3b from 1,3,5-Triethynylferrocenyl-2,4,6-Triferrocenyl Benzene (4) 105 3.5.1 Synthesis of 1,3,5-Trichloro-2,4,6-Triethynylferrocenyl Benzene (12) 105 3.5.2 Synthesis of 1,3,5-Triethynylferrocenyl-2,4,6-Triferrocenyl Benzene (4) 105 3.5.3 Synthesis of 3a and 3b from 4 106 4 Supporting information 107 4.1 Spectroelectrochemistry of 3a,b 107 4.2 Conversion of Isomer 9a to 9b – Electrochemical and Chemical oxidation 109 4.3 Chemical oxidation experiment 110 5 References 111 CHAPTER E Coordination Behavior of (Ferrocenylethynyl)diphenyl-phosphane Towards Binuclear Iron and Cobalt Carbonyls 114 1 Introduction 114 2 Results and Discussion 115 3 Experimental Section 126 3.1 Instrumentation 126 3.2 General 128 3.3 Reagents 128 3.4 Synthesis of 4 128 3.5 Synthesis of 4, 5 and 6 129 3.6 Synthesis of 6 by reacting 4 with 2 131 3.7 Synthesis of 7 and 8 131 3.8 Synthesis of 8 from 1 with 3 132 3.9 Synthesis of 9 in the reaction of 7 with 2 133 3.10 Synthesis of 9 in the reaction of 4 with 3 133 4 Electronic Supplementary Material (Supporting information) 134 5 References 134 CHAPTER F Summary 139 1 Conclusions of Chapter C (Appendix A) 139 2 Conclusions of Chapter D (Appendix B) 141 3 Conclusions of Chapter E (Appendix C) 142 Appendix 145 1 Appendix D (Chapter C) 145 2 Appendix E (Chapter D) 146 3 Appendix F (Chapter E) 147 Curriculum Vitae 150 Publications 152 Acknowledgements 154 Selbstständigkeitserklärung 155