Tetrasubstituted-Cyclobutadienepalladium Halides

Abstract

<p>Diphenylacetylenes, RC2R, (R=C6H5, p-ClC6H4 , p-CH3C6H4 , p-CH3OC6H4) reacted with palladium (II) complexes to give [R4C4OEtPdC1]2 , or [R4C4 (PdCl2)nI2 and R6C6. Hydrogen halides converted [R4C4OEtPdCl]2 to [R4C4PdX2]2.</p> <p>Particularly significant were the reactions in which a cyclobutadiene (R4C4) was transferred from palladium or nickel onto other metals. A very interesting reaction was the unprecedented ligand exchange.</p> <p>(R4C4PdX2)2 + 2(R'3P)2NiX2 -> (R4C4NiX2)2 + 2(R'3P)2PdX2 </p> <p>R'OH reacted with [R4C4PdX2]2 (except R=p-CH3OC6H4) to give exo[R4C4OR'PdX]2 and acids reversed this reaction. Some complexes [R4C4PdC5H5]+ were also made by ligand transfer of the cyclopentadienyl ligand onto palladium.</p> <p>1 H.N.M.R. studies of compounds derived from p,p'-disubstituted diphenylacetylenes showed that the phenyl region of the spectrum could be used to determine if the compound possessed the symmetry of a cyclobutadiene compound.</p>