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SUMMARY:Mechanistic Studies of Catalytically Relevant On-Metal N-Heterocyc
 lic Carbene Transformations
DTSTART;VALUE=DATE-TIME:20141120T063000Z
DTEND;VALUE=DATE-TIME:20141120T080000Z
DTSTAMP;VALUE=DATE-TIME:20260711T053645Z
UID:indico-contribution-719@events01.synchrotron.org.au
DESCRIPTION:Speakers: Tanita Wierenga (University of Tasmania\, School of 
 Physical Sciences - Chemistry)\nN-Heterocyclic Carbenes (NHCs) have many a
 dvantages to their phosphine analogues and have been used for a variety of
  catalytic applications. Bis-NHCs in particular have been used where biden
 tate phosphine complexes have previously been used including polymerisatio
 n and cross coupling reactions. Our group has been interested in palladium
  bis-NHCs with a wide variety of different N-substituents and linker lengt
 hs for catalytic applications. \n\nWe recently discovered an unexpected li
 gand rearrangement for a bis-NHC palladium complex when reacting the ethyl
 ene linked N-mesityl imidazolium salt with Pd(OAc)2. Along with the expect
 ed chelate formation an unusual C-C coupling product was also formed. DFT 
 calculations indicate the formation is through the decomposition of a norm
 al - abnormal intermediate via an on-metal ligand rearrangement. Given the
  extensive usage of this ligand class in catalysis and the decomposition r
 oute leading to this product it is important to understand and thus preven
 t its formation. \n\nDFT investigations established will be presented as w
 ell as synthetic studies probing the mechanism. Symmetrical analogues have
  been synthesised as well as unsymmetrical analogues blocking the C2 posit
 ion.\n\nAn alternative mechanism has also been explored for the decomposit
 ion of the chelate product to the C-C coupled product via the formation of
  a 1:2 ligand: palladium species. The NHC bridged dipalladium product has 
 been isolated and structurally confirmed by X-ray crystallography and show
 n to offer high yielding access to C-C coupled decomposition products.\n\n
 https://events01.synchrotron.org.au/event/3/contributions/719/
LOCATION: NCSS Exhibition Area
URL:https://events01.synchrotron.org.au/event/3/contributions/719/
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