Palladium(II) complexes bearing ethylene-bridged S boolean AND As and S boolean AND P donor ligands: synthesis, crystal structure and reactivity towards the polymerization of norbornene

Palladium(II) complexes of the general type [Pd(L boolean AND L)Cl-2] (4-6) and their corresponding dicationic complexes [Pd(L boolean AND L)(NCCH3)(2 )](BF4)(2) (7-9) (L boolean AND L = [(1-(thiomethyl)-2-(diphenylarsino)etha ne] (S boolean AND As, 1) (4, 7) [1-(thiomethyl)-2- (diphenylphosphino)etha ne] (S boolean AND P, 2) (5, 8) and [1,2-bis(diphenylphosphino)ethane] (P b oolean AND P, 3) (6, 9) have been synthesized and utilized as catalysts for the polymerization reaction of bicyclo[2.2.1]hept-2-ene (norbornene). The dichloride complexes can be activated with methylaluminoxane (MAO), while t he corresponding dicationic compounds were used as single component catalys ts for the polymerization reactions. Catalytic performance of the new type of catalyst can be altered by modifying the donor atoms in the bidentate li gand. The activity of the Pd(II) complexes towards the polymerization react ion increases with increasing the trans-influence of the donor atoms (P boo lean AND P > S boolean AND P > S boolean AND As). The influence of donor at oms on the length of the Pd-Cl bonds was elucidated by X-ray structure anal ysis carried out on the palladium(II) complex [Pd(S boolean AND As)Cl-2] (4 ). (C) 2000 Elsevier Science Ltd. All rights reserved.