Intermolecular Alkynyl Ligand Transfer in Palladium(II) and Platinum(II) Complexes with −C⋮CCOOR and −C⋮CPh Ligands. Relative Stability of the Alkynyl Complexes and Conproportionation of Dialkynyl and Diiodo Complexes of These Metals

Abstract

An equimolar reaction of trans-Pd(C⋮CCOOMe)2(PEt3)2 with trans-PdI2(PEt3)2 catalyzed by CuI causes conproportionation of the complexes at room temperature, producing trans-PdI(C⋮COOMe)(PEt3)2 in 88% yield, while the reaction without CuI catalyst gives the monoalkynylpalladium complex in approximately 2% yield after a prolonged period. Similar reactions of trans-Pd(C⋮CPh)2(PEt3)2 with trans-PdI2(PEt3)2 with and without CuI catalyst give the alkynyl ligand transfer reaction product trans-PdI(C⋮CPh)(PEt3)2 in 95% and 33% yields, respectively. CuI-catalyzed conproportionation of trans-Pt(C⋮CPh)2(PEt3)2 and trans-PtI2(PEt3)2 occurs more slowly than the corresponding reactions of the Pd complexes; trans-Pt(C⋮CCOOMe)2(PEt3)2 does not react with the diiodoplatinum complex even in the presence of CuI. The alkynyl ligand transfer reaction from trans-Pd(C⋮CCOOMe)2(PEt3)2 to trans-PtI2(PEt3)2 occurs in the presence of CuI catalyst, affording a mixture of several organopalladium and -platinum complexes. The main Pd co...