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Activation of CO2 by Palladium Complexes Bearing Tridentate PCP Ligands

Johansson, Roger LU (2007)
Abstract (Swedish)
Popular Abstract in Swedish

Avhandlingen berör aktivering av koldioxid genom inskjutningsreaktioner i palladium-kol bindningar. Detta har gjorts med komplexen (PCP)PdMe och (PCP)PdCH2CHCH2. Dessa komplex har också använts i katalytisk karboxylering of ZnMe2och tributylallyltenn. Pga. transeffekten är bindningen mellan palladium och metylgruppen kraftigt försvagad vilket visar sig i det långa bindningsavståndet för dessa atomer i kristallstrukturen. Flera (PCP)PdMe komplex har syntetiserats och testats i inskjutningsreaktioner, endast den mest nukleofila metallcentrat reagerade med koldioxid. En kinetisk undersökning av reaktionen visade att inskjutningen är första ordningen med avseende på både metallkomplexet och CO2.... (More)
Popular Abstract in Swedish

Avhandlingen berör aktivering av koldioxid genom inskjutningsreaktioner i palladium-kol bindningar. Detta har gjorts med komplexen (PCP)PdMe och (PCP)PdCH2CHCH2. Dessa komplex har också använts i katalytisk karboxylering of ZnMe2och tributylallyltenn. Pga. transeffekten är bindningen mellan palladium och metylgruppen kraftigt försvagad vilket visar sig i det långa bindningsavståndet för dessa atomer i kristallstrukturen. Flera (PCP)PdMe komplex har syntetiserats och testats i inskjutningsreaktioner, endast den mest nukleofila metallcentrat reagerade med koldioxid. En kinetisk undersökning av reaktionen visade att inskjutningen är första ordningen med avseende på både metallkomplexet och CO2. Samma undersökning visade också att övergångstillståndet består av ett komplex med koldioxid koordinerat och med en stor del bindningsbrytning respektive bindningsbildning. Inskjutningen av koldioxid i palladium-allyl bindningen är mycket snabbare och anses därför ske via en annan mekanism än för palladium metyl föreningen. Denna inskjutning är föreslaget att ske via ett cykliskt övergångstillstånd och är i princip inte en inskjutning men genom en omlagring kommer den bildade produkten att se ut som inskjutningsprodukten. Koldioxidinskjutning har också gjorts med palladiumhydroxid och palladiumhydrid för att ge karbonato respektive formiato komplexen, i båda fallen var reaktionen färdig inom ett par minuter. (PCP)PdH har också reagerats med fenylacetylen i en C-H utbytesreaktion vilket gav (PCP)PdCCC6H5 som den enda palladiuminnehållande produkten. Kristallstrukturen för ett flertal av de syntetiserade komplexen har lösts och dessa strukturer uppvisade en del intressanta packningsfenomen beroende av möjligheterna för vätebindningar, vilket har gett dimerer, kedjor och nät. (Less)
Abstract
The present thesis deals with the activation of CO2 by insertion reactions into palladium-carbon bonds. This has been realised for the complexes {2,6-bis[(di-t-butylphosphino)methyl]benzene}palladium(II)methyl [(PCP)PdMe] and (PCP)PdCH2CHCH2. These complexes have also been used in the catalytic carboxylation of ZnMe2 and Bu3SnCH2CHCH2. Because of trans influence the palladium-methyl bond is severely weakened as indicated by the long bond distance in the crystal structure of the complex. Several (PCP)PdMe complexes have been synthesised and tested in the insertion reaction but only the most nucleophilic metal centre gave any reaction. A kinetic analysis of this reaction revealed the insertion to be first order with respect to the metal... (More)
The present thesis deals with the activation of CO2 by insertion reactions into palladium-carbon bonds. This has been realised for the complexes {2,6-bis[(di-t-butylphosphino)methyl]benzene}palladium(II)methyl [(PCP)PdMe] and (PCP)PdCH2CHCH2. These complexes have also been used in the catalytic carboxylation of ZnMe2 and Bu3SnCH2CHCH2. Because of trans influence the palladium-methyl bond is severely weakened as indicated by the long bond distance in the crystal structure of the complex. Several (PCP)PdMe complexes have been synthesised and tested in the insertion reaction but only the most nucleophilic metal centre gave any reaction. A kinetic analysis of this reaction revealed the insertion to be first order with respect to the metal complex as well as to CO2. According to the same analysis the transition state of the reaction would consist of a complex with coordinated CO2 with a significant bond breaking and bond making. The insertion of CO2 into the palladium-allyl bond is a much faster reaction. Therefore it is considered to proceed via a different mechanism than what is operating for the (PCP)PdMe reaction. The reaction is proposed to involve a cyclic transition state and in principle not being an insertion, but due to rearrangement the product will appear as an insertion product. CO2 insertions have also been realised for palladium hydroxide and palladium hydride giving carbonato and formato complexes respectively. Both of these reactions are completed within minutes. (PCP)PdH have also been reacted with phenylacetylene in a C-H exchange reaction giving (PCP)PdCCC6H5 as the sole product. This product suggest a s-bond metathesis. The crystal structures for a number of the synthesised complexes have been solved and revealed some interesting packing arrangements governed by the possibilities for hydrogen bonding, giving rise to dimers, chains and 3D-nets. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Håkansson, Mikael, Göteborgs universitet
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Metallorganisk kemi, Organometallic chemistry, Kinetics, Insertion reactions, PCP ligands, CO2 activation, Palladium(II) complexes
pages
160 pages
publisher
Department of Chemistry, Lund University
defense location
sal E Kemiska instutionen Sölvegatan 39
defense date
2007-02-02 09:00
ISBN
978-91-7422-142-8
language
English
LU publication?
yes
id
20cbadb5-ac9a-4075-a6c2-afa622a2c7d3 (old id 547883)
date added to LUP
2007-10-09 11:18:26
date last changed
2016-09-19 08:45:07
@phdthesis{20cbadb5-ac9a-4075-a6c2-afa622a2c7d3,
  abstract     = {The present thesis deals with the activation of CO2 by insertion reactions into palladium-carbon bonds. This has been realised for the complexes {2,6-bis[(di-t-butylphosphino)methyl]benzene}palladium(II)methyl [(PCP)PdMe] and (PCP)PdCH2CHCH2. These complexes have also been used in the catalytic carboxylation of ZnMe2 and Bu3SnCH2CHCH2. Because of trans influence the palladium-methyl bond is severely weakened as indicated by the long bond distance in the crystal structure of the complex. Several (PCP)PdMe complexes have been synthesised and tested in the insertion reaction but only the most nucleophilic metal centre gave any reaction. A kinetic analysis of this reaction revealed the insertion to be first order with respect to the metal complex as well as to CO2. According to the same analysis the transition state of the reaction would consist of a complex with coordinated CO2 with a significant bond breaking and bond making. The insertion of CO2 into the palladium-allyl bond is a much faster reaction. Therefore it is considered to proceed via a different mechanism than what is operating for the (PCP)PdMe reaction. The reaction is proposed to involve a cyclic transition state and in principle not being an insertion, but due to rearrangement the product will appear as an insertion product. CO2 insertions have also been realised for palladium hydroxide and palladium hydride giving carbonato and formato complexes respectively. Both of these reactions are completed within minutes. (PCP)PdH have also been reacted with phenylacetylene in a C-H exchange reaction giving (PCP)PdCCC6H5 as the sole product. This product suggest a s-bond metathesis. The crystal structures for a number of the synthesised complexes have been solved and revealed some interesting packing arrangements governed by the possibilities for hydrogen bonding, giving rise to dimers, chains and 3D-nets.},
  author       = {Johansson, Roger},
  isbn         = {978-91-7422-142-8},
  keyword      = {Metallorganisk kemi,Organometallic chemistry,Kinetics,Insertion reactions,PCP ligands,CO2 activation,Palladium(II) complexes},
  language     = {eng},
  pages        = {160},
  publisher    = {Department of Chemistry, Lund University},
  school       = {Lund University},
  title        = {Activation of CO2 by Palladium Complexes Bearing Tridentate PCP Ligands},
  year         = {2007},
}