The Chemistry of the Dietl Complex, [Cl(MeC2Me)3PdCl]2

Abstract

In benzene solution at 10°, 2-butyne and bis(benzonitrile)palladium chloride reacted together to give the Dietl complex [(Me2c2)3PdC12]2. Reaction of this complex with Ph3E (E = P, As, Sb) gave hexamethyl-benzene, 1-vinyl-1,2,3,4,5-pentamethylcyclopentadiene, and 1-(1-chlorovinyl)-1,2,3,4,5-pentamethylcyclopentadiene. The complex was decomposed by hydrazine to the vinylpentamethylcyclopentadiene; with halogen hexamethylbenzene was formed; while lithium aluminum hydride gave largely 1-ethyl-1,2,3,4,5-pentamethylcyclopentadiene. In the presence of o-phenanthroline a new complex was formed, identified as 1-(chloro-(o-phenanthroline)palladium)-vinyl-1,2,3,4,5-pentamethylcyclopentadiene. Similar complexes were obtained with bipyridyl and pyridine. A structure for the Dietl complex is proposed and the mechanisms of some of its reactions are discussed.