848561-01-3Relevant academic research and scientific papers
Acrylonitrile insertion reactions of cationic palladium alkyl complexes
Wu, Fan,Foley, Stephen R.,Burns, Christopher T.,Jordan, Richard F.
, p. 1841 - 1853 (2007/10/03)
The reactions of acrylonitrile (AN) with L2PdMe + species were investigated; (L2 = CH 2(N-Me-imidazol-2-yl)2 (a, bim), (p-tolyl) 3CCH(N-Me-imidazol-2-yl)2 (b, Tbim), CH 2(5-Me-2-pyridyl)2 (c, CH2py′ 2), 4,4′-Me2-2,2′-bipyridine (d), 4,4′-tBu2-2,2′-bipyridine (e), (2,6- iPr2-C6H3)N=CMeCMe=N(2,6- iPr2-C6H3) (f)). [L 2PdMe(NMe2Ph)][B(C6F5)4] (2a-c) and [{L2PdMe}2(μ-Cl)][B(C6F 5)4] (2d-f) react with AN to form N-bound adducts L 2Pd(Me)(NCCH=CH2)+ (3a-f). 3a-e undergo 2,1 insertion to yield L2Pd{CH(CN)Et}+, which form aggregates [L2Pd{CH(CN)Et}]nn+ (n = 1-3, 4a-e) in which the Pd units are proposed to be linked by PdCHEtCN - Pd bridges. 3f does not insert AN at 23°C. 4a-e were characterized by NMR, ESI-MS, IR and derivatization to L2Pd{CH(CN)Et}(PR3)+ (R = Ph (5a-e), Me (6a-c)). 4a,b react with CO to form L2Pd{CH(CN)Et}(CO) + (7a,b). 7a reacts with CO by slow reversible insertion to yield (bim)Pd{C(=O)CH-(CN)Et}(CO)+ (8a). 4a-e do not react with ethylene. (Tbim)PdMe+ coordinates AN more weakly than ethylene, and AN insertion of 3b is slower than ethylene insertion of (Tbim)Pd(Me)(CH 2=CH2)+ (10b). These results show that most important obstacles to insertion polymerization or copolymerization of AN using L2PdR+ catalysts are the tendency of L 2Pd{CH(CN)CH2R}+ species to aggregate, which competes with monomer coordination, and the low insertion reactivity of L 2Pd{CH(CN)CH2R}(substrate)+ species.
