Novel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivity
This thesis describes the development of a range of polydentate phosphorus-containing ligands relevant to catalysis. The focus is on developing a fundamental understanding of how changes to the substituents on a ligand impact on the environment at a coordinated metal centre. Chapter 2 reports the sy...
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ndltd-bl.uk-oai-ethos.bl.uk-6009742016-08-04T04:14:05ZNovel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivityTuxworth, Luke William2014This thesis describes the development of a range of polydentate phosphorus-containing ligands relevant to catalysis. The focus is on developing a fundamental understanding of how changes to the substituents on a ligand impact on the environment at a coordinated metal centre. Chapter 2 reports the synthesis and coordination chemistry of the phosphine-alkene ligands N-R2P-7-aza-benzobicyclo[2.2.1]hept-2-ene, R = Ph (2-1) and iPr (2-2). The electronic properties of 2-1 and 2-2 are probed by a variety of methods, which reveals them to be electron deficient. The coordination chemistry of 2-1 to various transition metal fragments is then explored, exhibiting a range of coordination geometries including tetrahedral ([Ni(κ2-P,C-2-1)2] (2-6)), square based pyramidal ([RhCl(κ2-P,C-2-1)2] (2-7)) and trigonal bipyramidal ([IrCl(κ2-P,C-2-1)2] (2-8)). Chapter 3 introduces the problem of slow reductive elimination in some palladium-catalysed catalytic transformations along with methods of promoting this process, before describing the application of the electron deficient 2-1 in enhancing reductive elimination reactions. A detailed study of the formation of ethane by reductive elimination from a palladium dimethyl complex of phosphine-alkene ligand 2-1 has been undertaken. The mechanism of this process has been probed by a combination of experimental and computational studies and revealed that the mechanism proceeded via an associative mechanism through a 5-coordinate intermediate. Chapter 4 describes the synthesis and systematic study of the steric and electronic impact of a range of POCOP pincer ligands 1,3-{(tBu2PO)2C6H4} (4-1) and 1,3-{(R2PO)2C14H20}, R = tBu (4-7), OiPr (4-8), NEt2 (4-9), morpholine (4-10) and pyrrole (4-12). The coordination chemistry of these ligands is then appraised to probe the steric impact of the ligand crystallographically. Subsequently, the electronic impact of the ligands are assessed by 31P{1H} NMR and infrared spectroscopy of the corresponding phosphine selenide compounds and palladium carbonyl complexes. Chapter 5 reports exploratory reactions of a novel palladium hydride complex [PdH(κ3-P,C,P-4-1)] (5-1). The insertion of C=C (ethylene) and C=O (acetone, CO2) bonds into the Pd-H bond of 5-1 is attempted, notably showing facile insertion of CO2 to form the metal formate complex [Pd(OC(H)O)(κ3-P,C,P-4-1)] (5-4). Complex 5-1 is shown to be a catalyst for palladium-catalysed alkene isomerisation and aldehyde hydrosilylation, but the activity in both reactions is low.540Durham Universityhttp://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600974http://etheses.dur.ac.uk/10582/Electronic Thesis or Dissertation |
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540 Tuxworth, Luke William Novel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivity |
description |
This thesis describes the development of a range of polydentate phosphorus-containing ligands relevant to catalysis. The focus is on developing a fundamental understanding of how changes to the substituents on a ligand impact on the environment at a coordinated metal centre. Chapter 2 reports the synthesis and coordination chemistry of the phosphine-alkene ligands N-R2P-7-aza-benzobicyclo[2.2.1]hept-2-ene, R = Ph (2-1) and iPr (2-2). The electronic properties of 2-1 and 2-2 are probed by a variety of methods, which reveals them to be electron deficient. The coordination chemistry of 2-1 to various transition metal fragments is then explored, exhibiting a range of coordination geometries including tetrahedral ([Ni(κ2-P,C-2-1)2] (2-6)), square based pyramidal ([RhCl(κ2-P,C-2-1)2] (2-7)) and trigonal bipyramidal ([IrCl(κ2-P,C-2-1)2] (2-8)). Chapter 3 introduces the problem of slow reductive elimination in some palladium-catalysed catalytic transformations along with methods of promoting this process, before describing the application of the electron deficient 2-1 in enhancing reductive elimination reactions. A detailed study of the formation of ethane by reductive elimination from a palladium dimethyl complex of phosphine-alkene ligand 2-1 has been undertaken. The mechanism of this process has been probed by a combination of experimental and computational studies and revealed that the mechanism proceeded via an associative mechanism through a 5-coordinate intermediate. Chapter 4 describes the synthesis and systematic study of the steric and electronic impact of a range of POCOP pincer ligands 1,3-{(tBu2PO)2C6H4} (4-1) and 1,3-{(R2PO)2C14H20}, R = tBu (4-7), OiPr (4-8), NEt2 (4-9), morpholine (4-10) and pyrrole (4-12). The coordination chemistry of these ligands is then appraised to probe the steric impact of the ligand crystallographically. Subsequently, the electronic impact of the ligands are assessed by 31P{1H} NMR and infrared spectroscopy of the corresponding phosphine selenide compounds and palladium carbonyl complexes. Chapter 5 reports exploratory reactions of a novel palladium hydride complex [PdH(κ3-P,C,P-4-1)] (5-1). The insertion of C=C (ethylene) and C=O (acetone, CO2) bonds into the Pd-H bond of 5-1 is attempted, notably showing facile insertion of CO2 to form the metal formate complex [Pd(OC(H)O)(κ3-P,C,P-4-1)] (5-4). Complex 5-1 is shown to be a catalyst for palladium-catalysed alkene isomerisation and aldehyde hydrosilylation, but the activity in both reactions is low. |
author |
Tuxworth, Luke William |
author_facet |
Tuxworth, Luke William |
author_sort |
Tuxworth, Luke William |
title |
Novel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivity |
title_short |
Novel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivity |
title_full |
Novel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivity |
title_fullStr |
Novel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivity |
title_full_unstemmed |
Novel P-alkene and pincer-type POCOP ligands : synthesis, coordination chemistry, and reactivity |
title_sort |
novel p-alkene and pincer-type pocop ligands : synthesis, coordination chemistry, and reactivity |
publisher |
Durham University |
publishDate |
2014 |
url |
http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600974 |
work_keys_str_mv |
AT tuxworthlukewilliam novelpalkeneandpincertypepocopligandssynthesiscoordinationchemistryandreactivity |
_version_ |
1718373364979990528 |