Synthesis, Interionic Structure, and Reactivity toward CO and p‐Methylstyrene of Palladacyclic Compounds Bearing α‐Diimine Ligands

Abstract

AbstractPalladacyclic compounds [Pd(C6H4(C6H5CO)CNR)(NN)] [X] (R = Et, iPr, 2,6‐iPr2C6H3; NN = bpy = 2,2′‐bipyridine, or 1,4‐(o,o′‐dialkylaryl)‐1,4‐diazabuta‐1,3‐dienes; [X]− = [BF4]− or [PF6]−) were synthesized from the dimers [{Pd(C6H4(C6H5CO)CNR)(μ‐Cl)}2] and NN ligands. Their interionic structure in CD2Cl2 was determined by means of 19F,1H‐HOESY experiments and compared with that in the solid state derived from X‐ray single‐crystal studies. [Pd(C6H4(C6H5CO)CNR)(NN)] [X] complexes were found to copolymerize CO and p‐methylstyrene affording syndiotactic or isotactic copolymers when bpy or 1,4‐(o,o′‐dimethylaryl)‐1,4‐diazabuta‐1,3‐dienes were used, respectively. The reactions with CO and p‐methylstyrene of the bpy derivatives were investigated. Two intermediates derived from a single and a double insertion of CO into the PdC bonds were isolated and completely characterized in solution.