Synthesis and Stereochemistry of the First Chiral (Imidazolinylidene)‐ and (Triazolinylidene)palladium(ii) Complexes

Abstract

Abstract The reaction of three equiv. of a chiral imidazolium or triazolium perchlorate with one equiv. of Pd(OAc) 2 , an excess of NaI and a base leads to the corresponding chiral dicarbenediiodopalladium(II) complexes in chemical yields up to 98% and with the trans isomer as the major product ( 1, 2 ). If only one equiv. of the imidazolium or triazolium perchlorate is used, then dinuclear complexes with bridging iodine atoms are formed ( 3, 4 , chemical yield 92—94%). The latter can add Lewis basic ligands, e.g. amines, phosphanes or other carbenes, to give mononuclear complexes with one carbene ligand coordinated to the PdI 2 fragment ( 5, 6 ). Preliminary test experiments with these Pd(II) complexes as catalysts for an enantioselective Heck‐type reaction have been carried out.