Since the decisive breakthrough by Murai et al., who achieved a highly efficient ruthenium-catalyzed addition of aromatic C-H bonds to unsaturated substrates this reaction is recognized as a new category of chemistry. The compounds which were synthesized and presented in this thesis serve as stable models of reactive intermediates, proposed in catalytic transformations with the ruthenium counterparts. It is also general interest to study the reactivity of trimethylphosphine stabilized iron, cobalt and nickel compounds toward aromatic imines and ketones. Other than some cyclomanganated products, there are no examples of cyclometalated products of 3d row transition metals with imines. In this section, a review of reactions in the activation and functionalization of C-H bonds by solution-phase transition metal-based systems are presented, with an emphasis on the activation of aromatic C-H bonds. Phenyl ketimines react smoothly under mild contions with low–valent iron (0) and methyl-cobalt(I) adducts to form five-membered metallacycles. Stable cobalt(I) complexes are formed through reductive elimination of methane, and hydrido-iron(II) compounds arise from formal insertion of iron into the aromatic C-H bond. Benzylic imines react with Fe(CH3)2(PMe3)4 by elimination of methane to afford hexacoordinate methyl-iron(II) complexes. These are the first examples of ortho-metalated iron and cobalt complexes with imine anchoring groups which are fully characterized.An imine function is the nitrogen analogue of a carbonyl group. Following the isolecetronic principle, CoCH3(PMe3)4 with ketones affords cyclometalated, diamagnetic cobalt(I) compounds through methane elimination under same reaction conditions. Even though C-F bonds are about 30 kcal/mol stronger than C-H bonds, partially fluorinated 2,3,4,5,6-pentafluorobenzophenone reacts with CoCH3(PMe3)4 via C-F activation by elimination of fluoromethane. Upon combining a dimethyliron compound with certain diarylated imines, a reaction sequence is observed consisting of double metalation at the same metal complex center leading to a metallabicycle. Fe(CH3)2(PMe3)4 affords bicyclo-metalated iron(II) compounds with N-(1-naphthylmethylene)-aniline and N-Benzylbenzylideneimine. Co(CH3)(PMe3)4 forms hydrido-cobalt(III) complexes.
Item Type: |
Ph.D. Thesis
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Erschienen: |
2005 |
Creators: |
Camadanlı, Şebnem |
Type of entry: |
Primary publication |
Title: |
Cyclometalation and Bicyclometalation Reactions of Trimethylphosphine Supported Iron, Cobalt and Nickel Compounds via C-H Activation with Imine and Carbonyl Anchoring Groups |
Language: |
English |
Referees: |
Fessner, Prof. Dr. Wolf-Dieter |
Advisors: |
Klein, Prof. Dr. Hans-Friedrich |
Date: |
7 September 2005 |
Place of Publication: |
Darmstadt |
Publisher: |
Technische Universität |
Refereed: |
18 July 2005 |
URL / URN: |
urn:nbn:de:tuda-tuprints-6032 |
Abstract: |
Since the decisive breakthrough by Murai et al., who achieved a highly efficient ruthenium-catalyzed addition of aromatic C-H bonds to unsaturated substrates this reaction is recognized as a new category of chemistry. The compounds which were synthesized and presented in this thesis serve as stable models of reactive intermediates, proposed in catalytic transformations with the ruthenium counterparts. It is also general interest to study the reactivity of trimethylphosphine stabilized iron, cobalt and nickel compounds toward aromatic imines and ketones. Other than some cyclomanganated products, there are no examples of cyclometalated products of 3d row transition metals with imines. In this section, a review of reactions in the activation and functionalization of C-H bonds by solution-phase transition metal-based systems are presented, with an emphasis on the activation of aromatic C-H bonds. Phenyl ketimines react smoothly under mild contions with low–valent iron (0) and methyl-cobalt(I) adducts to form five-membered metallacycles. Stable cobalt(I) complexes are formed through reductive elimination of methane, and hydrido-iron(II) compounds arise from formal insertion of iron into the aromatic C-H bond. Benzylic imines react with Fe(CH3)2(PMe3)4 by elimination of methane to afford hexacoordinate methyl-iron(II) complexes. These are the first examples of ortho-metalated iron and cobalt complexes with imine anchoring groups which are fully characterized.An imine function is the nitrogen analogue of a carbonyl group. Following the isolecetronic principle, CoCH3(PMe3)4 with ketones affords cyclometalated, diamagnetic cobalt(I) compounds through methane elimination under same reaction conditions. Even though C-F bonds are about 30 kcal/mol stronger than C-H bonds, partially fluorinated 2,3,4,5,6-pentafluorobenzophenone reacts with CoCH3(PMe3)4 via C-F activation by elimination of fluoromethane. Upon combining a dimethyliron compound with certain diarylated imines, a reaction sequence is observed consisting of double metalation at the same metal complex center leading to a metallabicycle. Fe(CH3)2(PMe3)4 affords bicyclo-metalated iron(II) compounds with N-(1-naphthylmethylene)-aniline and N-Benzylbenzylideneimine. Co(CH3)(PMe3)4 forms hydrido-cobalt(III) complexes. |
Alternative Abstract: |
Alternative abstract | Language |
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Seit dem entscheidenden Durchbruch von Murai et al., die eine hocheffiziente Ruthenium-katalysierte Addition aromatischer C–H-Bindungen an ungesättigte Substrate entwickelt haben, wird diese Methode einer neuen Kategorie organisch-chemischer Synthesen zugerechnet. Alle neuen Verbindungen, die in der vorliegenden Dissertation präsentiert werden, lassen sich als stabile Modelle reaktiver Zwischenstufen ansehen, die in katalytischen Umwandlungen mit analog zusammengesetzten Rutheniumkomplexen vorgeschlagen werden. Darüber hinaus ist es von allgemeinem Interesse, die Reaktivität Trimethylphosphin-gestützter Eisen-, Cobalt- und Nickel-Verbindungen gegenüber aromatischen Iminen und Ketonen zu untersuchen. Abgesehen von einigen cyclomanganierten Produkten gibt es von Metallen der 3d Übergangsreihe keinerlei Beispiele für Cyclometallierungen mit Iminen. In diesem Abschnitt wird ein Überblick von Reaktionen mit Aktivierung und Funktionalisierung von C-H-Bindungen durch Übergangsmetall-Verbindungen in Lösung gegeben unter besonderer Berücksichtigung der Aktivierung aromatischer C–H-Bindungen. Phenylketimine reagieren unter milden Bedingungen glatt mit niedervalenten Komplexen von Eisen(0) und Cobalt(I) unter Ausbildung fünfgliedriger Metallacyclen. Stabile Cobalt(I)-Komplexe bilden sich durch reduktive Eliminierung von Methan, während Hydridoeisen(II)-Komplexe durch formale Insertion des Eisens in eine aromatische C–H-Bindung generiert werden. Benzylimine reagieren mit Fe(CH3)2(PMe3)4 unter Eliminierung von Methan zu hexakoordinierten Methyleisen(II)-Komplexen. Diese Verbindungen sind die ersten Beispiele für ortho-metallierte Einsen- und Cobalt-Komplexe mit Imin-Ankergruppen, die umfassend charakterisiert werden konnten. Eine Imin-Funktion ist das N-Analogon einer Carbonylgruppe. Auf der Basis dieser isoelektronischen Verwandtschaft reagiert unter gleichen Bedingungen CoCH3(PMe3)4 mit Ketonen unter Eliminierung von Methan zu cyclometallierten, diamagnetischen Cobalt(I)-Verbindungen. Obwohl C–F-Bindungen um etwa 30 kJ/mol stärker sind als C–H-Bindungen, reagiert hälftig fluoriertes 2,3,4,5,6-Pentafluorbenzophenon mit CoCH3(PMe3)4 unter C–F-Aktivierung und Eliminierung von Fluormethan. Vereinigt man Dimethyleisen mit bestimmten diarylierten Iminen, wird eine Reaktionssequenz beobachtet, die in einer doppelten Metallierung am gleichen Metallkomplexzentrum besteht und einen Metallabicyclus generiert. Während Fe(CH3)2(PMe3)4 mit N-(1-naphthylmethylen)anilin und N-Benzyl-benzylidenimin bicyclometallierte Eisen(II)-Verbindungen liefert, bildet CoCH3(PMe3)4 entsprechende Hydridocobalt(III)-Komplexe. | German |
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Uncontrolled Keywords: |
Orthometalierung, Trimethylphosphan, Imin, Carbonyl |
Alternative keywords: |
Alternative keywords | Language |
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Orthometalation, trimethylphosphine, imine, carbonyl, iron, cobalt, nickel, C-H activation, C-F activation, bicyclometalation, C-C coupling | English |
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Classification DDC: |
500 Science and mathematics > 540 Chemistry |
Divisions: |
07 Department of Chemistry |
Date Deposited: |
17 Oct 2008 09:22 |
Last Modified: |
26 Aug 2018 21:25 |
PPN: |
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Referees: |
Fessner, Prof. Dr. Wolf-Dieter |
Refereed / Verteidigung / mdl. Prüfung: |
18 July 2005 |
Alternative keywords: |
Alternative keywords | Language |
---|
Orthometalation, trimethylphosphine, imine, carbonyl, iron, cobalt, nickel, C-H activation, C-F activation, bicyclometalation, C-C coupling | English |
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