Palladium(II) complexes containing P≁N≁O donors.: Ligand effect of tritdentate versus bidentate coordination on the oligomerization of ethylene

Palladium complexes containing the [(RO)(n)C6H5-nC=]N(C6H4PPh2-o) (Psimilar toNsimilar toO) ligand were synthesized, and the hemilability of the coordinating oxygen donors toward the metal center was' studied. In the case of oxygen being a ether functionality (R Me), acetonitrile readily replaces the tridentate ether donor in [Pd(Psimilar toNsimilar toO)Me]BF4 (1) to yield [Pd(Psimilar toNsimilar toO)(MeCN)Me] BF4 (2). The labile nature of the ether donor assists the complex 1 in catalyzing the oligomerization of ethylene. Presumably, the temporary coordination of the ether donor to the vacant site during migratory insertion suppresses the beta-elimination, which allows the elongation of the. alkyl chain.