Abstract:Neutral trans-[Pd(C 6 F 5 )XL 2 ] (X ) Cl, Br) and cationic trans-[Pd(C 6 F 5 )L 2 (NCMe)]BF 4 (L ) SbPh 3 , AsPh 3 , As(C 6 Cl 2 F 3 )Ph 2 , AsCyPh 2 , AsMePh 2 , PPh 3 ) complexes have been studied and tested for norbornene (NB) polymerization and copolymerization with 5-norbornene-2-carboxaldehyde (NB-CHO). The neutral complexes are almost inactive and produce only small amounts of oligomers, but the cationic complexes with arsines and stibines are very good for palladium-catalyzed norbornene polymerization… Show more
“…The system 7/MAO generally yielded higher activities than 4/MAO. This is reasoned with a kinetic activation effect through a faster removal of the more weakly bound AsPh 3 ligand in 7 over the PPh 3 ligand in 4 upon reaction with MAO together with the C 6 F 5 ligand to give the active Pd species (see below) [77]. The weaker AsPh 3 bonding is based on the longer PdeAs (w2.36 A) over the shorter PdeP bond (2.23 A) [49].…”
Section: Norbornene Homopolymerizationmentioning
confidence: 99%
“…In addition, the still present and stronger coordinating PPh 3 ligand can compete in equilibrium with the NB monomer for the free metal coordination site (Eq. (3)) which, as a consequence, slows the chain growth rate [77,69]. Such a PPh 3 /ethene competition is used in the Shell higher olefin process (SHOP) to control the oligomer chain length [70].…”
“…The system 7/MAO generally yielded higher activities than 4/MAO. This is reasoned with a kinetic activation effect through a faster removal of the more weakly bound AsPh 3 ligand in 7 over the PPh 3 ligand in 4 upon reaction with MAO together with the C 6 F 5 ligand to give the active Pd species (see below) [77]. The weaker AsPh 3 bonding is based on the longer PdeAs (w2.36 A) over the shorter PdeP bond (2.23 A) [49].…”
Section: Norbornene Homopolymerizationmentioning
confidence: 99%
“…In addition, the still present and stronger coordinating PPh 3 ligand can compete in equilibrium with the NB monomer for the free metal coordination site (Eq. (3)) which, as a consequence, slows the chain growth rate [77,69]. Such a PPh 3 /ethene competition is used in the Shell higher olefin process (SHOP) to control the oligomer chain length [70].…”
“…This effect was interpreted to result from easy replacement of the weakly coordinated ligands by NBE along with the formation of the catalytically active species. [39] Hence, it seemed reasonable to check whether in our polymerization reaction the primary phosphane ligand remained coordinated to palladium. To this purpose, we analyzed, by multinuclear NMR spectroscopic experiments, two different polymerization reactions carried out at low temperature in an NMR tube.…”
Section: Nmr Spectroscopic Monitoring Of Polymerization Experimentsmentioning
“…In this way the Pd-fluoroaryl moiety has been used as a reporter of the symmetry of the molecule and has allowed the study of a variety of complex fluxional processes, isomerization, and ligand substitution and exchange reactions, 25 as well as the study of palladium-catalyzed polymerization reactions. 26 A review covering the use of fluroraryl groups as reporter tools is available. 27 Also, the use of 19 F NMR has been very important in the study of other processes where the Pd-R F bond is cleaved and these examples will be discussed here.…”
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