Palladium Complexes Containing Large Fused Aromatic N−N Ligands as Efficient Catalysts for the CO/Styrene Copolymerization

Bis(homoleptic) palladium(II) complexes of the extended aromatic ligands eilatin ([Pd(eil)2][BF4]2 (1a))
and dipyridophenazine ([Pd(dppz)2][BF4]2 (2a), [Pd(dppz)2][PF6]2 (2b)) were synthesized and employed
in the copolymerization of carbon monoxide and styrene. The eilatin ligand in the complex [Pd(eil)2][BF4]2 is bound via its less hindered “head” coordination site. The X-ray structure of 2b was solved and
indicated a highly twisted square planar geometry around the palladium center and the presence of
π-stacking interactions of two types. All complexes were found to be active catalysts for the synthesis
of the syndiotactic CO/styrene polyketone, their activity exceeding that of the parent complex [Pd(phen)2][BF4]2.