REACTIONS OF PALLADIUM COMPOUNDS WITH ACETYLENES: II. TETRAKIS(p-CHLOROPHENYL)CYCLOBUTADIENE PALLADIUM COMPLEXES

Abstract

It is found that both diphenylacetylene and bis(p-chlorophenyl)acetylene on reaction with bis(benzonitrile)palladium chloride in benzene give the benzenoid trimer (R6C6) as well as a new type of cyclobutadiene complex [(R4C4)(PdCl2)x]2(R = Ph and p-ClC6H4) for which structure IV is proposed. p,p′-Dichlorotolan reacts with bis(benzonitrile)palladium chloride in ethanol – methylene chloride to give a complex [(R4C4OC2H5)PdCl]2 (II) which is converted into the normal cyclobutadiene complex [(R4C4)PdBr2]2 (V) on treatment with hydrogen bromide. This can also be obtained from IV. The tetrakis(p-chlorophenyl)cyclobutadiene palladium halides on treatment with tri-n-butylphosphine give a dimer of tetrakis(p-chloro-phenyl)cyclobutadiene which is probably octakis(p-chlorophenyl)cyclooctatetraene. Tetrakis-(p-chlorophenyl)cyclobutadiene iron tricarbonyl has also been prepared from IV and V by a ligand-transfer reaction.