Basic chelating phosphines

Milstein and colleagues [100] have developed very efficient methods using basic, chelating phosphine ligands. Even aryl chlorides underwent reductive dechlorination to the corresponding arenes with ](dippp)2Pd] as catalyst (dippp,... 

The reactivity order Ni>Pd>Pt has been found for the oxidative addition of aryl halides. Steric and electronic properties, and the numbers of L as well as chelate effects, play an important role [65, 194—196]. For example, Pd(0) complexes of basic chelating phosphines react substantially more easily with chlorobenzenes than their nonchelating analogues (see Section 18.2.4) [2, 100, 196]. 

Recent use of phosphine ligands in the areas of catalysis,3,4 pentacoordination,5,6 and oxidative-addition reactions7 has prompted investigations into variations of donor basicity, chelate chain length, and mixed sets of donor atoms. Thus, relatively accessible synthetic routes to chelating aliphatic phosphines are needed. Removal of sulfur from a diphosphine disulfide8 and subsequent preparation of NaPR2 in liquid ammonia provides a useful laboratory route to aliphatic phosphines. For example,... 

There are few exceptions in zirconium/phosphine compounds to the basic [ZrCl3L2]2 structural motif. The presence of the chelating phosphine ligand dppe [bis(diphenylphosphino)ethane] in a toluene solution of ZrCl4 results in the formation of the green compound,... 

The rate of carbonyl insertion in chelating Pd complexes (N—0)Pd(R)L decreases with increasing basicity of the phosphine ligand L and with L = PCy3... 

With longer irradiation times and chelating "" or basic " phosphine and arsine ligands, di- and even trisubstituted complexes are obtained, indicating that carbonyl loss from excited M(CO)jL] obtains. Carbonyl loss occurs preferentially to phosphine loss and not as a minor pathway ... 

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