摘要:
Acrylonitrile (AN) displaces the ethyl ether ligand of the cationic complex [Pd(N-N)Me(Et2O)](+) (N-N = (2,6-(i-Pr)(2)C6H3)- N = CMeCMe = N-(2,6-(i-Pr)(2)C6H3)) to form the N-bonded AN complex [Pd(N-N)Me(AN)](+), which exists as two interconverting rotamers. On standing or heating, [Pd(N-N)Me(AN)](+) undergoes 2,1-insertion to give [Pd(N-N)(CH(CN)CH2Me)(AN)](+), which undergoes beta-hydrogen elimination to give the intermediate hydride, [Pd(N-N)H(AN)](+), which in turn inserts AN to give the cyanoethyl complex [Pd(N-N)(CH(CN)Me)](+). Dimerization of the [Pd(N-N)(CH(CN)CH2CH3)](+) moiety via bridging nitrile groups also occurs, giving the dicationic species [Pd(N-N)(CH(CN)CH2Me)](2+)(2). Although [Pd(N-N)Me(AN)](+) does behave as a typical Brookhart ethylene polymerization catalyst, it does not catalyze AN polymerization and in fact added AN suppresses ethylene polymerization. (c) 2005 Elsevier B.V. All rights reserved.