A variety of neutral palladium(II) complexes [Pd(L-L)Cl-2] containing 1,3-di(2-pyridyl)propane (1), 1,3-bis(2-pyridyl)-2-pentylpropane (2), 1,3-bis(2-pyridyl)-2-phenylpropane (3a), 1,3-bis(2-pyridyl)-2-tolylpropane (4), and 1,3-bis(2-pyridyl)-2-ferrocenylpropane (5) as chelate ligands (L-L) have been synthesized. The crystal structures of 1,3-diphenyl-2,4-di-pyridin-2-yl-butan-1-ol (3b), 5, [(2)PdCl2], [(4)PdCl2], and [(5)PdCl2] have been determined and show a square planar geometry at palladium(II). The neutral complexes were tested in the polymerization of norbornene and copolymerization of norbornene with norbornene derivatives. The complex bearing the pentyl group exhibited high reactivity to give up to 5.9 x 10(5) in molecular weight for the homopolymerization. When [(4)PdCl2] or [(5)PdCl2] was used as a catalyst, homopolymers insoluble at 150degreesC in trichlorobenzene were obtained. However, copolymerization of norbornene with norbornene derivatives 8a-d catalyzed by [(4)PdCl2] gave soluble copolymers with molecular weights up to 5.1 x 10(5). (C) 2003 Elsevier B.V. All rights reserved.