<p>Transition metals have played an important role in synthetic organic chemistry for more than a century, and offer catalytic transformations that would have been impossible with classical chemistry. One of the most useful and versatile of the transition metals is palladium, which over the years has catalyzed many important carbon-carbon forming reactions. Popular cross-coupling reactions such as the Suzuki, Stille and the Heck reaction are all catalyzed by palladium, or more correctly, by palladium in its ground state, Pd(0). </p><p>Recently, interest in palladium(II)-catalyzed transformations has started to grow, partly due to the development of the vinylic substitution reaction, commonly called the oxidative Heck reaction, presented in this thesis. This Pd(II)-catalyzed, ligand-modulated reaction occurs under air at room temperature, and for the first time a general protocol employing a wide range of olefins and arylboronic acids was obtained. Ligand screening showed that the bidentate nitrogen ligand, 2,9-dimethyl-1,10-phenanthroline (dmphen), was the most suitable ligand. Dmphen is believed to facilitate regeneration of active Pd(II), increase catalytic stability and improve the regioselectivity in the reaction. A mechanistic investigation was conducted using electrospray ionization mass spectrometry (ESI-MS), making it possible to observe cationic intermediates in a productive oxidative Heck arylation. The results obtained are in agreement with the previously proposed catalytic cycle.</p><p>The emerging discipline of high-speed synthesis is making contributions to society’s growing demand for new chemical entities. This inspired the development of two ultrafast, microwave-accelerated carbonylation reactions with dicobalt octacarbonyl acting both as an in situ carbon monoxide supplier and reaction mediator. A wide range of symmetrical benzophenones was produced in only 6 to 10 s, using aryl iodides as the substrate. The second carbonylation reaction provided symmetrical and unsymmetrical ureas in process times ranging from 10 s to 40 minutes using primary and secondary amines.</p>

Transition metals have played an important role in synthetic organic chemistry for more than a century, and offer catalytic transformations that would have been impossible with classical chemistry. One of the most useful and versatile of the transition metals is palladium, which over the years has catalyzed many important carbon-carbon forming reactions. Popular cross-coupling reactions such as the Suzuki, Stille and the Heck reaction are all catalyzed by palladium, or more correctly, by palladium in its ground state, Pd(0). Recently, interest in palladium(II)-catalyzed transformations has started to grow, partly due to the development of the vinylic substitution reaction, commonly called the oxidative Heck reaction, presented in this thesis. This Pd(II)-catalyzed, ligand-modulated reaction occurs under air at room temperature, and for the first time a general protocol employing a wide range of olefins and arylboronic acids was obtained. Ligand screening showed that the bidentate nitrogen ligand, 2,9-dimethyl-1,10-phenanthroline (dmphen), was the most suitable ligand. Dmphen is believed to facilitate regeneration of active Pd(II), increase catalytic stability and improve the regioselectivity in the reaction. A mechanistic investigation was conducted using electrospray ionization mass spectrometry (ESI-MS), making it possible to observe cationic intermediates in a productive oxidative Heck arylation. The results obtained are in agreement with the previously proposed catalytic cycle. The emerging discipline of high-speed synthesis is making contributions to society’s growing demand for new chemical entities. This inspired the development of two ultrafast, microwave-accelerated carbonylation reactions with dicobalt octacarbonyl acting both as an in situ carbon monoxide supplier and reaction mediator. A wide range of symmetrical benzophenones was produced in only 6 to 10 s, using aryl iodides as the substrate. The second carbonylation reaction provided symmetrical and unsymmetrical ureas in process times ranging from 10 s to 40 minutes using primary and secondary amines.

Palladium-catalyzed reactions have become one of the most important tools in modern organic chemistry due to its ability to catalyze the formation of new carbon-carbon bonds. The aim of the work presented in this thesis was to develop new palladium(II)-catalyzed addition reactions. In this work, cyanamides were investigated as a new substrate to give aryl amidines as products. The first protocol developed employed aryltrifluoroborates as the aryl partner, and the insertion of the aryl group into un-, mono-, and di-substituted cyanamides was successful for a wide variety of aryltrifluoroborates. An alternative method of generating the necessary intermediate for insertion into the cyanamide is the decarboxylative formation of aryl-palladium from aryl carboxylic acids. A protocol was developed for this reaction, but was unfortunately limited to a small number of ortho-substituted electron-rich aryl carboxylic acids. The mechanism was investigated by the means of DFT calculations and ESI-MS studies, and the rate-determining step was suggested to be the 1,2-carbopalladation based upon those results. A translation of the batch protocol to continuous-flow conditions was also demonstrated. The ideal method of generating the aryl-palladium species is by C-H bond activation, and this approach was demonstrated with indoles, giving a variety of 3-amidinoindoles as products. The mechanism was investigated by DFT calculations and a plausible catalytic cycle was proposed. A continuous-flow application of a desulfitative palladium(II)-catalyzed addition to nitriles to give ketones was developed. In addition, different reactor materials were evaluated in the microwave heated reactor cavity. Thus the reaction was shown to proceed with microwave heating in a borosilicate glass and an aluminum oxide reactor, and also in conditions mimicking conventional heating in a silicon carbide reactor. Finally, a protocol was developed for the convenient synthesis of sodium aryl sulfinates from Grignard and lithium reagents using a solid sulfur dioxide source as a safe alternative to the gas. The products of this protocol can be used as aryl-palladium precursors by a desulfitative process.

Die vorliegende Arbeit befasst sich mit der Synthese, dem Reaktionsverhalten, den Festkörperstukturen und den elektronischen Eigenschaften von neuartigen Übergansmetall-komplexen der Gruppen 4, 8 und 10 des Peridoensystems der Elemente. Die Arbeit befasst sich unter anderem mit der Darstellung von Alkyloxy- und Aryloxy-substituierten Titanocenverbindungen des Typs [Ti](Cl)(OR) {[Ti] = (C5H5SiMe3)2Ti; R = organischer Rest). Mittels cyclovoltammetrischer Experimente und anhand von Festkörpestrukturen wird der elektronische Einfluss der organischen Reste auf das Metallzentrum untersucht. Weiterhin befasst sich die Arbeit mit der Synthese von in para-Position substituierten NCN-Pincerverbindungen. Durch die Wahl des Substituenten in para-Postition sowie des Übergangsmetalls der Gruppe 10 des Periodensystems der Elemente ist es möglich, verschiedenartig gerichtete polymere Strukturen zu bilden. Ein weiterer Schwerpunkt der vorliegenden Arbeit liegt in der Synthese und Untersuchung der elektronischen Eigenschaften von NCN-Pincer-substituierten Ferrocenen. Der Einfluss der NCN-Pincer auf die Elektronendichte des Ferrocens wird bestimmt sowie die Eignung derartiger Systeme als elektrochemische Sensoren zur molekularen Erkennung von Schwefeldioxid wird untersucht.

Die vorliegende Arbeit beschäftigt sich mit der Synthese, dem Reaktionsverhalten und der Elektrochemie von Bimetallocen- und Metallocen-haltigen Komplexen. Die Eignung von Bis(ethinyl)biferrocen- und Bis(ethinyl)biruthenocen-haltigen Brückenbausteinen, intramolekularen Elektronentransfer zwischen zwei identischen Eisen-, Ruthenium- und Osmium-Halbsandwich-Fragmenten zuzulassen, wurde mittels geeigneter Spektroskopiearten untersucht. Weiterhin wurden zwei verschiedene Übergangsmetallkomplexfragmente über den Bis(ethinyl)biferrocen-Brückenbaustein miteinander verknüpft um neuartige gemischte Übergangsmetallacetylide zu erhalten, an welchen ebenfalls Elektronentransferstudien durchgeführt werden konnten. Zusätzlich waren Biferrocenyl- und Metallocenyl-Phosphane Gegenstand der Untersuchungen. Es erfolgte einerseits die Koordination an PtCl2- und Pt(CCFc)2-Fragmente. Die so erhaltenen neuen heterometallischen Platin(II)-Bisacetylide wurden mittels Cyclovoltammetrie und UV-Vis-NIR-spektroelektrochemischen Methoden untersucht um herauszufinden, in welchem Ausmaß Ladungen delokalisiert vorliegen können. Die Biferrocenyl- und Ruthenocenyl-Phosphane wurden andererseits an PdCl2-Bausteine koordiniert und im Anschluss auf ihre Wirksamkeit als (Prä-)Katalysatoren in Palladium-vermittelten Heck- und Suzuki-C-C-Kupplungsreaktionen getestet.

Die vorliegende Arbeit beschäftigt sich mit der Synthese, dem Reaktionsverhalten und der Elektrochemie von Bimetallocen- und Metallocen-haltigen Komplexen. Die Eignung von Bis(ethinyl)biferrocen- und Bis(ethinyl)biruthenocen-haltigen Brückenbausteinen, intramolekularen Elektronentransfer zwischen zwei identischen Eisen-, Ruthenium- und Osmium-Halbsandwich-Fragmenten zuzulassen, wurde mittels geeigneter Spektroskopiearten untersucht. Weiterhin wurden zwei verschiedene Übergangsmetallkomplexfragmente über den Bis(ethinyl)biferrocen-Brückenbaustein miteinander verknüpft um neuartige gemischte Übergangsmetallacetylide zu erhalten, an welchen ebenfalls Elektronentransferstudien durchgeführt werden konnten. Zusätzlich waren Biferrocenyl- und Metallocenyl-Phosphane Gegenstand der Untersuchungen. Es erfolgte einerseits die Koordination an PtCl2- und Pt(CCFc)2-Fragmente. Die so erhaltenen neuen heterometallischen Platin(II)-Bisacetylide wurden mittels Cyclovoltammetrie und UV-Vis-NIR-spektroelektrochemischen Methoden untersucht um herauszufinden, in welchem Ausmaß Ladungen delokalisiert vorliegen können. Die Biferrocenyl- und Ruthenocenyl-Phosphane wurden andererseits an PdCl2-Bausteine koordiniert und im Anschluss auf ihre Wirksamkeit als (Prä-)Katalysatoren in Palladium-vermittelten Heck- und Suzuki-C-C-Kupplungsreaktionen getestet.

Thirteen new dinuclear complexes of ligand 2,6-bis[(N-methylpiperazine-1- yl)methyl]-4-formyl phenol (L1) were prepared. Copper(II) and palladium(II) salts were used for the syntheses. Following compounds were prepared: [Cu2L1(CH3COO)2]ClO4, [Cu2L1(CF3COO)2(ClO4)][Cu2L1(CF3COO)2]ClO4, [Pd2L1(CH3COO)3], [Pd2L1(CF3COO)3], [Pd2L1(Cl)4]. These ones should act as anion receptors. The acetates were exchanged for phenylphosphinates in the case of the complex cation [Cu2L1(CH3COO)2]+ and the structure of [Cu2L1(phPO2H)2]ClO4 was obtained. Geometry of coordination shell of Cu2+ - ions in prepared complexes is tetragonal pyramid. The UV-VIS spectroscopy was used for study of interactions in system of the ligand - metal - anion. Interactions between the ligand and metals in oxidation state 2 were observed as well as interactions between the complex [Cu2L1(CH3COO)2]ClO4 and sodium salts.

Palladium complexes have the ability to catalyse cross-coupling of two organic moieties through the formation of transient metal-carbon bonds, thus bringing them closer to each other to facilitate the formation of a new bond. Palladium-catalysed coupling reactions are one of the most important carbon-carbon forming reactions available to organic chemists and many of these reactions rely on the reactivity of aryl-palladium complexes. The investigation of new aryl-palladium precursors is thus of great interest, especially as more sustainable and economic methods can be developed. This thesis describes the use of carboxylic acids and sodium arylsulfinates as such new arylating agents. Protocols for microwave-assisted palladium(II)-catalysed decarboxylative synthesis of electron-rich styrenes and 1,1-diarylethenes were developed. However, these transformations had very limited substrate scopes which prompted the investigation of sodium arylsulfinates as alternative arylating agents. These substrates were employed in the microwave-assisted palladium(II)-catalysed desulfitative addition to nitriles, and the substrate scope was demonstrated by combining a wide array of sodium arylsulfinates and nitriles to yield the corresponding aryl ketones. The application of the desulfitative reaction in a continuous flow setup was demonstrated, and aluminium oxide was identified as safe alternative to borosilicate glass as a reactor material. The mechanisms of the decarboxylative and desulfitative transformations were investigated by density functional theory (DFT) calculations. The desulfitative reaction was also investigated by direct electrospray ionization mass spectrometry (ESI-MS), providing further mechanistic insight. Finally, a protocol for the safe and convenient synthesis of a wide range of sodium arylsulfinates was developed.

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