Palladium complexes containing

The first examples of highly active olefin polymerization catalysts based on late transition metals were nickel and palladium complexes containing bulky diimine ligands.310 312 For example, complex (120) was found to polymerize ethylene with an activity of ll,000gmmol h bar A range of PE materials with molecular weights up to 106 and... 

With the exception of intramolecular amination reactions, all of the early aryl halide aminations were catalyzed by palladium complexes containing the sterically hindered P(o-tol)3. In papers published back-to-back in 1996, amination chemistry catalyzed by palladium complexes of DPPF and BINAP was reported.36,37 These catalysts allowed for the coupling of aryl bromides and iodides with primary alkyl amines, cyclic secondary amines, and anilines. 

Catalytic enantioselective synthesis of 4,4-dimethyl-l-phenyl-l,2-pentadiene from 4,4-dimethyl-1,2-pentadiene and iodobenzene using 0.4 to 1 mol % of palladium complexes containing chiral phosphane ligands as the catalyst for the enantioselective cross coupling134 is the only example of substoichiometric transition metal catalyzed enantioselective allene synthesis. 

Highly selective transformation of terminal acetylenes to either linear or branched carboxylic acids or esters may be achieved by appropriately selected catalyst systems. Branched esters are formed with high selectivity when the acetylenes are reacted with 1-butanol by the catalyst system Pd(dba)2/PPh3/TsOH (dba = dibenzylideneacetone) or palladium complexes containing PPh3. Pd(acac)2 in combination with various N- and O-containing phosphines and methanesulfonic acid is also an efficient catalyst for the alkoxycarbonylation of 1-alkynes to yield the branched product with almost complete selectivity.307,308... 

Dicarboxylic acids form monomeric complexes with palladium(II), K2[Pd(X2)2] (X2 = oxalate, malonate, etc,).153154 They may be prepared by warming a suspension of palladium(II) chloride with a concentrated solution of the alkali metal dicarboxylate or by using other palladium complexes containing readily substituted ligands such as [Pd(OH)2], [Pd(N03)2(H20)2] or [Pd(02CMe)2]3-155 These complexes are claimed to have useful antitumour properties.155 Complexes [Pd(X2)L2] (X2 = dicarboxylate L = amine or L2 = diamine) may be prepared by reaction of the dichloro complex with a carboxylate salt.156,128... 

Reactions and Structures of Palladium Complexes Containing Bis(diphenylphosphino)methane as a Bridging Ligand... 

Three papers have appeared in the past two years on catalysts that are either supported on polymers or are heterogeneous. Djakovitch first reported animation reactions catalyzed by palladium particles immobilized on metal oxide supports, as well as by palladium complexes contained in NaY zeolites [172]. In most cases, these reactions were conducted at high temperatures, generally 135 °C. When NaOtBu was used as the base, competing amination through a benzyne intermediate was observed. Thus, para meta regioselectivity was not high, and reaction yields were modest. 

Better catalytic behavior was observed in the copolymerization of CO and norbornadiene with palladium complexes containing a hemilabile pyridyl-carbene ligand [23]. The choice of a pyridine-functionalized carbene can be explained by the fact that the hemilabile arm in such a ligand is capable of reversible dissociation from the metal center, leading to vacant coordination sites for the complexation of the substrates while the strong donor moiety remains bound to the metal. 

In general, the active homogeneous palladium complexes contain a halide ion (133), typically chloride, in the coordination sphere. The influence of halide ions on the Pd zeolite catalysts would therefore seem worthy of study. 

Extensive mechanistic studies have been conducted on the oxidative addition of aryl halides to Pd(0) complexes ligated by PPh3 in different media and with different additives175, 176. However, palladium complexes containing these ligands are not active catalysts for amination. Instead, one must consider the addition of aryl halides to palladium complexes bound by ligands relevant to amination. Studies of the mechanism of oxidative addition to palladium(O) complexes of P(tol-o)3, DPPF, BINAP, Q-phos, P(Bu-f)3 and an /V-heterocyclic carbene ligand have been reported. 

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